YFZ450 Jetting .

[Quad18star]

I'm wondering if a Moderator would be able to sticky something liek this for us . How about we set up what everyone is running for their jetting in the YFZ450 . I know it's a pain in the butt to have to search all over to find the answers . It's just a suggestion and I'm sure it would help a lot of people out , as well as stop a lot of threads about jetting info .... it could be like a one stop shop for jetting . :D

Anyways here's my setup ...

Full Curtis Sparks stainless steel exhaust with Sparks Racing filter and adapter (no airbox lid) , along with Sparks racing jet kit .

Approx . 1000 feet above sea level
Temperature between 65 - 80 F with an average of 72F

45 Pilot jet
178 Main jet ( cuz it's cold right now)
NCVQ needle with clip on middle setting
2 1/2 turns out on the fuel screw

These settings seems to be fine for now ... but has a little bit of popping on de-accel . Could be caused by the cold temps ??

[Fred55]

GYTR Aluminum Slip-on
168 M
45 P
4th clip on NVCQ needle
2 turns out on fuel screw
GYTR Foam filter, no air box lid

[Splatter Matter]

DR.D pipe

172 main
45 pilot
4th nvcq needle
2 1/4 turns fuel screw

K&N air filter no lid

[jlhughes750]

NCVQ dirtbike needle clip on the middle

172 main

45 pilot

94 octane sunoco fuel or VP 10?

Sparks full pipe

Sparks foam filter and Sparks ring
also ran K&N with pro design intake ring with same jetting.

I'm in eastern Pa. not positive of the elevation??

[TheWolf]

what about the fuel you are using? I would assume that no mention would be pump gas. You should mention what fuel you use if it is race gas or oxigenated gas.

Also if you know your altitude, mention that.



Thanks

[Fred55]

I changed mine lol, the other one kept fouling plugs?

now im at a
165m
42pilot (stock)
NVCQ 3th clip
Fuel screw 3 turns out

[sampleez]

i finally got my pipe in, and my jetting felt pretty good, but it was about 30 degrees, so i'll have to lean it up a little when it warms up. i have a Dr. D slip-on, the cam mod, and the air box lid off with the stock filter set-up. i run 93 gas, and my elevation is about 750-1500. my jetting is:

172 main
48 pilot
stock needle in 5th position
fuel screw about 2.5 turns out

[Quad18star]

Thanks to everyone who has responded so far ..... but come on you other guys ... post up . Help fellow riders out ... I know there are a LOT more of you guys out there with pipes .... especially when this thread has gotten over 300 views .

[cdalexct]

178 main
45 pilot
ncvq on 5th
2 turns on fuel screw
94 sunoco fuel

[Quad18star]

Originally posted by cdalexct
178 main
45 pilot
ncvq on 5th
2 turns on fuel screw
94 sunoco fuel

Stock pipe ?? airbox lid on or off? Temps ?? Elevation ??

[cdalexct]

Originally posted by Quad18star
Stock pipe ?? airbox lid on or off? Temps ?? Elevation ??

HMF full system
airbox lid off with prodesign proflow kit(foam)
airbox lid outwear
35 degrees out runs good
Live in PA dont know Elevation

[Quad18star]

Originally posted by cdalexct
HMF full system
airbox lid off with prodesign proflow kit(foam)
airbox lid outwear
35 degrees out runs good
Live in PA dont know Elevation

Perfect ... thanks for posting more info .... I think the average Elevation in PA is the same as I have ... anywhere from 700ft to 1300 ft .

[Bill Fuller]

HMF full system with Quiet core insert
UM aluminium air box w/250R Uni foam filter,lid on
North Tenn 500ft elvation
Fuel screw at 2 turns out
165main
45 pilot
NCVQ needle on 3rd clip
94 Ultimate

[Fred55]

Thats exactly what im running except a 42 pilot, what temp are you at?

[Bill Fuller]

Wintertemps range from 20 to 50 degrees.I was running a 162 until I put on the UM airbox/250R Uni.

[Fred55]

Your like the only other person that ive seen with a 165 besides me...everybody says to try 168, and i tried that and i was WAY too rich...weird huh

[Bill Fuller]

I followed HMF instructions and my quad ran like CRAP.I started with the 175 main and the 45 pilot.I went to the NCVQ needle right from the start.It took about 2 months to get it to where I am now,believe me I tried all the combos.I finally ordered jets from 160 to 180(Carb parts wharehouse:macho)When I had the 170 in it ran like there was water in the gas.When I kept messing around,thought I was there with the 165 main.After going to H/M last year I realized that weasn't right either.I started to think there was a deeper problem(rectifier/electric).But I finally got the 162 in and BINGO there it was.

[Fred55]

yeah it seems that you and i are leaner that everybody else, which is weird too...with full exhausts and filters, i wonder what is causing them to go up so high as 172 and even 180 as hmf suggests

[SRH]

what do you guys recommend for this setup as a good starting point

lid on
dr d slip on w/ fmf powerbomb "sx" header
cam mod
uni air filter
1200 ft above sea level
60-80 degrees
pump gas 93

from what i read about what alot of guys run i was thinking a good starting point would be

168 or 170 main ( what do you guys think)
45 pilot
nvcq needle 4th clip
air screw 2.5 turns out

anyone have a better idea for a good starting point? my quad felt sluggish at times last year and had a slight bottom end hesitation at times with the dyno junk kit and i really wanna solve that

[Fred55]

I have a 165 main
42 pilot(stock)
3rd clip on NVCQ clip
3 turns out on fuel screw

Im at about 1000-1100 ft
and at the moment temps are around 40, i raced a 1 hour harescramble yesterday and it ran great.

[sampleez]

hey srh
main sounds pretty good, pilot will prolly need to be a 48, but 45 might work if it's pretty warm. everything else looks pretty close too

i think upping the pilot is supposed to help the bog

and did you get the header and pipe at the same time, or did you have the stock header on for a while. i was wondering how much that header you have helps. i am really impressed with the dr.d so far tho.

[ESrider]

168 main
45 pilot
airbox lid removed
stock pipe with insert removed
350 feet above sea level
93 octane

[Quad18star]

SRH .... that sounds like a good starting point !!!

[AshYFZ450]

Altitude: Sea Level (Glamis, Gordans, Ogilby)
Temp: Hot (days) Cold (nights) 50f-80f
Cam Mod Yes
Intake: K&N (stock manifold with airbox removed completely)
Exhaust: GYTR slip-on
Main: 172
Pilot: 48
Needle: NCVQ 3rd clip
Fuel Screw: ZipTY 2 1/2 turns

[tgyolai]

i am new to this i am running no lid with pro design air filter system just got sparks header and silencer main is 165 pilot is 42 3rd groove from topon needle this was gytr jet kit i dont know where the fuel screw is so dont know where that is set

[Quad18star]

Originally posted by tgyolai
i am new to this i am running no lid with pro design air filter system just got sparks header and silencer main is 165 pilot is 42 3rd groove from topon needle this was gytr jet kit i dont know where the fuel screw is so dont know where that is set

I'd run a bit higher main jet ... Sparks recommends a 175 I believe . Also bump that pilot up to atleast a 45 . The fuel screw is underneath the carb and is ressed in ... you'll need a long skinny flat head screw driver to get at it . 2 1/2 turns is what is recommended with Sparks .

[tgyolai]

thanks quad18star

[SRH]

Originally posted by sampleez
hey srh
main sounds pretty good, pilot will prolly need to be a 48, but 45 might work if it's pretty warm. everything else looks pretty close too

i think upping the pilot is supposed to help the bog

and did you get the header and pipe at the same time, or did you have the stock header on for a while. i was wondering how much that header you have helps. i am really impressed with the dr.d so far tho.

yeah i like the dr d, i havent run with the powerbomb yet , im actually waiting for it to come in, should be next week or so

[aci clay]

168 main 45 pilot, stock needle,fuel screw 3 turns out, lid off, pro design foam filter,3000 ft. elevation so cal hi desert

[dudleydoright15]

I am running a 05, yfz450 with a white brothers E-2 full exhaust with air box lid off and pro flow filter.

175 main
42 pilot
needle out of a yz450 on needle clip position 4
1 1/2 turns out


elevation is between sea level and 500ft.


works great but a little bit of popping when I let off of the gas.

[450Rcarbonpro]

washington evlevation 800 to 1000 ft.
degrees 50 to 80

[Bill Fuller]

I tried everything up to a 180 main.I tried the NCVQ needle on clip positions from 2 to 5 clips.I never tried anything above a 45 pilot.My bike would run like shiat from 1/2 throttle up until I started moving to what I was being told was lean.Once I started coming down she ran better and better until I finally came up with my settings=45 pilot,3rd clip on NCVQ needle and a 162 main.I have a HMF full system with Quiet Core insert,airbox with lid on.(No engine mods)Runs GREAT!!:muscle:

[Quad18star]

What would cause a flame to shoot out of the exhaust ???

I'm running a 175 main , 45 pilot, 2 1/2 turns on the fuel screw .... full sparks system with foam filter and adapter , no air box lid .

The temps are hot right now ... like 80+ degrees and Im at about 1000 feet.

[drgnerth]

When does it do it? Wot, idle, all the time. You look to be rich on the main.

[drgnerth]

By the way.
170 main 45 pilot middle clip on NCVQ 1 3/4 on air/fuel mixture 800 ft above sea level.

Ron Woods intake, no air box, K&N w/ outerwear, Hot Cams, WR crank, rod, piston, full HMF sport.

[Quad18star]

My dad just took my quad out yesturday , and he said it was really missing in the higher RPMs . I didn't really get to see him or hear him on it , so I can't tell if it was the motor bouncing off the rev limited ( I have stock gearing with 18" rear tires) or if it was my jetting .

What would you guys recommend for jetting of an 04 with full system Sparks pipe and filter setup ?? The temps are in and around the freezing mark right now and the last time I checked my plug it was really rich , but that was with hot temps .

[JDiablo]

WHat will you guys reccomend for this setup?
Rossier full exhaust
CFM open airbox with UNI filter
Cam mod
elevation 700-1000
Temp 25-45ish
Can anyone give me a good place to start at thanks

[Quad18star]

When all else fails for jetting , just forget to install the main jet and let that sucker run rich . :cool:

[E.POWERSPORTS]

Can you post the stock jetting on a '04?

[onall4rs]

i have a full yoshi system, air box lid off,180 main 42 pilot,air screw rounded off :eek: and its not turning. engine a pig to start
hot or cold
help

[xcnick38]

full system yoshimura TRC...

158 main
50 piolet
new needle i think 3rd clip

air box lid is on and im also in PA it runs great...

[onall4rs]

i drilled the air screw out today and have a new comeing on friday
so hope to heve the problem solved

[drue4mpg]

06' yfz450

Bill Ballence GYT-R titanuim head and pipe
High flow No Box lid
165 main jet
45 pilot
GYT-R needle Clip 3
2 full turns
seattle 200'
it seems to be dialed in no bog or lag through out the range
made a huge difference on the 3rd groove and taking it back from 2 1/2 to only two turns
its so fast now my girl wont get on it anymore .........PERFECT

[drue4mpg]

GYT-R Titainum full
Pro intake LID OFF
(Bill Balence Kit)
165
45
GYT-R 3rd clip
2 1/2 turns

Seattle WA,
I'm around 400 feet
70 degrees

[yfzcrazy]

I need help i just got the velocity intake and purchased the FMF titanium4 full exhaust and iam not sure what jets to use or even how to figure it out. i was reading your colum and noticed a lot of stuff i dont understand like the fuel screw turns or the size of the jets or temps and elevation. Well i live in san diego so temps are usaully between 50-80 at sea level but i love to go to the desert but i am unsure of the elevation. any help will be great thanks.

[jcline]

165 Main Jet
Pilot, Fuel Screw, and Needle Position Stock
Stock Pipe w/ Baffle Removed
Stock Filter w/ Air Box Lid On
93 Octane Pump Gas

[BrianEX]

I just bought a Big Gun Race Series complete exhaust and will need to rejet. Any recommendations of where to start would help. Only other mods are: no airbox lid and a K&N filter.

Rockford, IL Elevation is around 800 feet.
Temp: 65 degrees

Thanks.

[husa]

Hello,

I´m new here and have registered for one question.
(I have no quad, but a keihin carburretor from YFZ450,year 2004)

I installed it in my husaberg enduro.

I´m surching for a good jetting, and have spend a lot of time in the web.
(It´s quite plain to me, that your jettings must not be the best for my engine (501ccm, longstroke), I will not just copy this )

The stock needle was a NDS-R

The most people here changed to NCV-Q

looking in the keihin.us needle chart
http://www.keihin-us.com/am/_media/pdf/fcr_jetneedles.pdf

the needles are termed OC-XXX

(OB is possible too, I know the difference to OC)

Is a NCVQ in full term OB-NCV???
This is improtand for me to get information about the diameter and so on.
And when this is right, was does the smaller fourth letter "R" mean?
for example Kawasaki has a NCVR needle in the FCR40 (KX450F Motocross...)

thanks in advance!

[06 YFZ FATBOY 4]

06 YFZ 450: 172 MAIN, 42 PILOT,NCVQ 4TH, K&N NO LID, FATBOY 4 FULL SYSTEM, EXHAUST CAM MOD, 2.5 TURNS ON FUEL SCREW, ELEVATION 2000'-2300', 17-30 CELCIUS=APPROX 65F? IAM HAVING PROBLEMS WITH TOP END WOT, I AM GOING TO TRY 45 PILOT & 175 MAIN TODAY IF IT STOPS SNOWING YAH THATS RIGHT SNOWING:mad: ON APRIL 19. SHEEET I SHOULD BE RIPPING UP THE SAND WITH MY BOYS!!!!!!!. IF ANYONE HAS CLOSE TO THIS SET UP ON THE 06 WITH NO TROUBLE @ 3/4 TO WOT PLEASE POST IT.

[Xater]

what do you guys think the jetting should be with baffle out and lid removed?

[sdbrown12388]

'06 with full gyt-r exhaust, gyt-r air filter
165 main
42 pilot
3rd clip
2 and a half turns

[bradley300]

i noticed no one is mentioning the leak jet??? are you guys having problems with the stumble off idle when you stab the throttle?

louisville, KY
stock filter, no lid
HMF slip on

170 main
NDSR needle #3 down
45 pilot
2 out on the feul screw
30 leak jet
raised the idle just a hair from what would sound normal. it doesnt scream, but its a little more than a slow chug like you would hear on a 400ex

very slight stumble off the bottom when stabbing the throttle from nothing to full, but a 25 leak jet should fix it.

[06 YFZ FATBOY 4]

BRADLY 300: I DONT HAVE A PROBLEM WITH A STUMBLE WHEN I STAB THE THROTTLE, IT WAS JUST @ 3/4 TO WOT, IT SEEMED TO HAVE MORE TOP END @ 3/4 THROTTLE THEN IT DID @ WOT. I PUT A 175 MAIN AND PLAYED WITH FUEL SCREW, THIS CLEANED UP MY PROBLEM @ WOT. QUESTION- IF I PUT A 45 PILOT IN WOULD I NEED TO PUT A 178 MAIN JET FOR MORE FUEL TO MATCH UP WITH THE MORE AIR? I THINK SO BUT NOT TO SURE. MORE FUEL & MORE AIR = MORE POWER?

[bradley300]

i doubt it, but you'll only know once you ride it

[06 YFZ FATBOY 4]

Thanks for the replie, the more you work on them the more you learn. have a great & safe summer!!!!:cool:

[06 YFZ FATBOY 4]

BRADLEY 300. I got it figured out 175 main, 42 pilot, 2 turns on fuel screw, ncvq 4th, k&n no lid, cam mod, fatboy 4 full system, 15 tooth sprocket, elevation 2000'- 2500' approx. works great no hesitation off bottom end, no bobble at 3/4 to wot:D thanks for everyones help on this sticky!!!!this thing hauls ***** now!!!:D

[yfzrider310]

for the stock exaust with the baffle removed do i have to change the jetting or should i just leave it stock

[jcline]

I changed the main jet to a 160 and took the air box lid off. Runs great!

[06 YFZ FATBOY 4]

Originally posted by yfzrider310
for the stock exaust with the baffle removed do i have to change the jetting or should i just leave it stock The answer is yes you should change your jetting, take your air box lid off and see how it runs.

[yfzrider310]

does taking the airbox lid off make that big of a difference??

[ohsobad_chevy]

Northern Oklahoma: Approx. 700 ft.

2007 YFZ 450 SE
Curtis Sparks X6 pipe
UNI air filter w/o airbox lid
Air temp around 74 degrees

165 main
45 pilot
4th clip on NCVQ needle
All the way in and 2.5 out on the screw

:cool:

[jcline]

Taking the air box lid off was a must after I changed the main jet. It did'nt run right otherwise. The combination of the changes gave me noticeably more on the low end.

Ported head
web +5 cams
WR crank
CP 13:1 piston
Stock airfilter. half a airbox. back is cut off.And screen removed
C12 fuel
Sparks bigcore exhaust

In nj not sure elevation.

180 main
48 pilot
Stock needle 5th clip down
2 1/2 turns out

Professionally dynoed where these were the best settings.

[06 YFZ FATBOY 4]

I just bought a 07 se, elevation 2000- 3000, temp +10 deg, main 175, pilot 42, no lid, cam mod!!, drilled out exhaust, ncvq 4th clip from bottom, 2 1/4 turn on fuel screw. I still have the 06. blown motor. any body with a 04- 05 -06 do the oil mod NOW!!! or your looking at lots of $$$$ for parts. crank seized not enough oil to the crank. :grr: :mad:

[sylvan_srt4]

2004 yfz
elevation : 2800 feet
mods : alba full pipe, velocity air filter w/o air lid
main 170
pilot 45
stock needle 5th clip
fuel screw 2.5 turns out

[X-Factor]

DASA fullsystem
Complete racing Head
ProDesign with lid off (Foam)
DynoJet kit - 142 main & 48 pilot
Elevation 500ft
Average Temp - 77

[BrettOaktree]

HMF sport series slipon and K&N air filter with the airbox lid on

928FT elevation

165 main
48 pilot
1 turn out on the fuel screw
3rd needle clip
93 valero fuel

runs really good power throught the entire rpm range and doesnt backfire

[moisey_4]

Im in Seattle Wa so my guess is that its sea level-1000ft.

Ron woods full exhaust
ron woods intake system with k&n no airbox
Pump gas

jetting:
175 main
48 pilot
5 postition on needle (from top)
1 1/2 turns out on fuel screw

Seems rich but rips, and never had to chang a spark plug yet.

[06billballance]

new here but want to put my 2 cents in,06 yfz 450 bill ballance,white bros slip on,175 main,48 pilot,stock needle,adjustable mixture screw,in omaha ne.this thing runs great.neck and neck with a buddies ktm 525

[toomey450]

i have a 06 yfz 450 with the toomey slip on, and k&n air filter no lid. the slip on came with a 175 main jet but it just wasnt right. when you stab the throttle it chokes the quad out. and my choke switch doesnt work, when you pull it out it kills the bike.

i just bought a gytr jet kit for it but im not sure witch jets to put in and what to set the needle as... any suggestions?

[ohsobad_chevy]

Not for sure how the numbers are on the GYTR jets. Is the 175 main a Keihin jet or a GYTR? It should have a little K with a star if its a keihin.

[toomey450]

not sure what kind of main jet it is. they just sent it to me with the toomey slip on pipe.

Originally posted by toomey450
not sure what kind of main jet it is. they just sent it to me with the toomey slip on pipe.

How do you like the toomey? And do you have a soundclip?
Ive always been curious about them because they advertised for the yfz and I wanted to know how their 4-stroke pipe is.

[ohsobad_chevy]

Originally posted by toomey450
not sure what kind of main jet it is. they just sent it to me with the toomey slip on pipe.

Well, does it have a K and a star on it or just a size number.

[toomey450]

it had a star on it and all the jets that came with the gytr jet kit have stars to.

and the pipe is off the chain if you like it loud and mean. it gave it a lot more horsepower and it made it a lot louder, its just the jet that came with it isnt quite working for me.

[SMS]

It seems we usually end up with this combo in Ohio

55 pilot
165-170 mj
we use the magnum needle 2nd clip
and we like it better than the other needle we have tried
and we use the r&d adjustable leak jet bowl adjuster screw 2 3/4 out
we also use the r&d flex jet fuel screw 2-3 out

Pipe and air box lid off
The magnum jet kit comes with needle and 165,170,175 main jet we sell all the iteams need to jet your YFZ as well.

[SMS]

It seems we usually end up with this combo in Ohio

55 pilot
165-170 mj
we use the magnum needle 2nd clip
and we like it better than the other needle we have tried
and we use the r&d adjustable leak jet bowl adjuster screw 2 3/4 out
we also use the r&d flex jet fuel screw 2-3 out

Pipe and air box lid off
The magnum jet kit comes with needle and 165,170,175 main jet we sell all the iteams need to jet your YFZ as well.

[dingaling02]

I just changed the jetting on my stock 06 yfz. I wanted to ask a few questions before I starting riding it. I just installed a slip on HMF pipe, and used dynojets jet kid for the 450. I went with their specs and they are way off, as to what everyone else runs.
I live in indiana, so around 700-1300 ft, and temps in summer are avg. 80, starting here in a month or so, it will be around 30-40.
this is what I started with, and we'll see where I should be. I used all Dynojet stuff, so their needle, 3rd clip, a 150 main, and a 45 pilot. I run the lid off with stock filter, as of now, I just ordered a k&n filter, and will mostly run with the lid off, except for casual riding around the farm, I put the lid back on.
Is it okay, to run the lid on and off, and not do much changing.
Also, I have the a/f needle turned out 1 turn. That sounds majorly different than everyone else. I wanted to run these numbers by you guys first, before I started riding. I am a newb to most of this, but have done a lot of reading and following you guys write ups!!

Thanks in Advance,
Corey P

[SMS]

From what I know dyno jet uses different jets and needle setup than what most of us use. As far as running lid on and off it needs to be jet each way.

[dingaling02]

would you suggest ordering a new jet kit. I would like to get what everyone would suggest as the best.... Any information would be great. I know that their stuff did seem quite a bit different from that of every other brand.

[SMS]

If it was mine I would use the same set up we all have.

[dingaling02]

SMS, I am kind of starting to think you might be right, I just hate to maybe admit defeat on what I already have!!! I will get back with you about your pm as well..Thank you very much.

Now, I talked to dynojet today, and they are the most erogant people I have ever met. I told them that everyone else is using a larger sized jet, than what they even offer. The guy says, why is that, and i tell him, most are using a 168+ main jet, and I am using a 150. He says, what is infront of the 150, and I said CJ, he then proceeds to ask what is in front of everyone elses, I say nothing. So, he tells me that is the reason, they are not the same, so leave it at that. I guess that wasn't good enough. He just said dynojet is tried and true, so why look for suggestions. That really disgusts me, to hear not to ask questions, just do what the paper says. I guess if these quads for 500 bucks, I wouldn't care, but I've got 7K in this, and can't risk tearing it up, because they don't want to compare themselves to someone else.

Morale of this story: I CJ150 Dynojet is not a typical 150, it is something completely different from what everyone else has, and cannot be compared, IM TOLD!! I guess they are venturi jets, which I understand, but i have no way of cross referencing to anyone..
Anyone else have any luck with manufacturers like I did!!
Thanks everyone for all of your help!

[SMS]

I just try to help to save everyone time and money, so they can ride!

[450Rrider13]

i live in green bay wisconsin and im getting my quad set up for the winter so around 0-30 degrees. its got a powercore 4 slip on and a mega bomb header. any ideas on what i should run for jets??

[SMS]

62 pilot 175 mj fuel screw out 2 turns I like the ndsr needle 3rd clip

[Bill Fuller]

62 Pilot Jet?????????????:eek2:

[BennyYFZ]

I'm new to the jetting stuff, but I want to learn how to jet it myself and see good results. Is this a good starting kit for me? My mods are in my sig, and I'm fixin to add a 15t front sprocket on pretty soon.

http://cgi.ebay.com/ebaymotors/YAMAHA-YFZ450-VITOS-JET-KIT-OEM-CARB-YFZ-450-2005-2008_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116 QQitemZ200189280724QQptZMotorsQ5fATVQ5fPartsQ5fAcc essories

Thanks for all the help guys :)

[ohsobad_chevy]

62 pilot is WAAAYYY too rich, I would start with a 48 and go from there.

Benny, If I were you, I would order the "NCVQ" needle and buy your jets separately (keihin jets) from your dealer or you can get them from jetsrus.com

With your mods, I would start with a 175 main, 45 pilot, NCVQ needle on the 3rd clip and 2 turns out on the screw. That will get you close. ;)

[Bill Fuller]

Although I agree with ohsobad I would like to point out the NVCQ needle is very rich. I had quite a time with getting it right. I like the 50 pilot, NDSR 3rd clip down and 170 main. Fuel screw if you have on will need to be adjusted accordingly. It is also nearly impossible to jet one of these carbs while on the stand, you need to ride it after every change, the carb reacts differently when underload IMO. I would also recommend changing the leak jet to get rid of the bottom end bog. Alot of the bog can be removed by proper jetting but you still will have a slight hesitation, until you get that adjusted.


Good Luck

[Bill Fuller]

Benny the jet kit you show doesn't state wich needle that is. I would contact GTthunder.com and get his kit or order your carb parts from carbparts.com they have the best prices for individual jets, I think when I orderd the jets where like 2.50 or so each. I bought from 160-180 cost me like 20 bucks or so.

I can't see what is in your sig to help much more, I turned off sigs ALONG time ago.

[BennyYFZ]

hey guys, thank you for the information!

I will see what I can come up with here w/ jetting changes.

Bill, my mods are:

2004 Yamaha YFZ450
Ron Woods full exhaust
Cam mod
CP Race Piston 94mm
Velocity Intake w/ airbox removed

I'm in DFW, Texas which is roughly 600ft above sea level. Temps are roughly in the 50's these days.

[WoodsRacer16]

Hey i have just got in to racing xc this summer in middle tn and i never jetted a quad in my life.I have a stock 07 yfz 450 and i just got my new hmf pipe.Could yall just tell me what i need to do and how to do it lol... im a little lost on it...thanks

[ohsobad_chevy]

Originally posted by WoodsRacer16
Hey i have just got in to racing xc this summer in middle tn and i never jetted a quad in my life.I have a stock 07 yfz 450 and i just got my new hmf pipe.Could yall just tell me what i need to do and how to do it lol... im a little lost on it...thanks

Start with a 170 main, 45 pilot, 3rd needle position, and 2.5 out on the screw. That will get you close.

[Bill Fuller]

45 pilot is to lean. I wouldn't put anything less than a 48. NSDR needle 3rd clip 170-175 main with open airbox.

[ohsobad_chevy]

Originally posted by Bill Fuller
45 pilot is to lean. I wouldn't put anything less than a 48. NSDR needle 3rd clip 170-175 main with open airbox.

Jetting isn't the same for everyone, temperature, elevation, different pipes, carbs, intakes, etc etc.
There is no way to tell him EXACTLY what he would need. That will get him close.

I have a sparks pipe and FCI intake on my 07 and a 48 pilot is way too rich, even in the colder months.

[Bill Fuller]

Except for the fact that he lives an hour away from me with close to the same set up. And I agree that it's only a starting point and I UNDERSTAND elvation, humudity, temperature, setup ETC......

[mxpimp2000]

can anyone help me out on jetting

HMF slipon
cam mod
uni filter no lid
13:1 piston
168 main
48 pilot
2 1/2 turns out
stock needle non adj
temps are around 80-90 when i ride and im 500-550 ft above sea level in the lower Ky area

bike is hesitating when u punch it from 1/2 throttle and if u hold it at half in nuetral it will cut in and out and backfire when u punch it from 1/4 it dies people are telling me its my jetting i just had motor rebuilt and changed exhaust from a TC full system to a hmf slipon with stock header, i didnt mess with the jetting any

[ohsobad_chevy]

Adam,
We have answered you many times in your thread. We told you what jets/needle to order......have you done so??

[yfz4506]

What jetting should i use, i have
GYTR slip on
K&N filter with pre-charger baggy NO LID
05 bottom end with 06 head

[ohsobad_chevy]

Originally posted by yfz4506
What jetting should i use, i have
GYTR slip on
K&N filter with pre-charger baggy NO LID
05 bottom end with 06 head

Start with 170 main, 45 pilot, 3rd clip on needle and 2 turns out on the screw.

[erikschmitt]

04 yfz 450
white brothers e2 slip on
everything else stock air box lid is on
where should i start with the jetting?

[liquidivide300]

I just purchased a 2007 yfz last thursday. The bike came with a full rocket exhaust, and uni air filter and a few jets. the owner i bought it from said the main jet in the carb was stock. I took the bike home and it ran like crap. It was missing in every gear and had no power. i was getting beat all day by a stock 2006 ltz 400. I changed the pipe and header back to stock and was still missing in the low gears. 3rd through 5th it ran awesome. I do a lot of fast tight woods riding about 1500 to 2200 above sea level. I would like to keep it mostly stock for now. Dose anybody know the stock pilot/main jets. Ride in 45 to 90 degree weather. Any help would really be appricated.

Thanks

[ohsobad_chevy]

Originally posted by erikschmitt
04 yfz 450
white brothers e2 slip on
everything else stock air box lid is on
where should i start with the jetting?

Start with a 45 pilot, 170 main, 3rd clip needle and 2 turns out on the screw.


Originally posted by liquidivide300
I just purchased a 2007 yfz last thursday. The bike came with a full rocket exhaust, and uni air filter and a few jets. the owner i bought it from said the main jet in the carb was stock. I took the bike home and it ran like crap. It was missing in every gear and had no power. i was getting beat all day by a stock 2006 ltz 400. I changed the pipe and header back to stock and was still missing in the low gears. 3rd through 5th it ran awesome. I do a lot of fast tight woods riding about 1500 to 2200 above sea level. I would like to keep it mostly stock for now. Dose anybody know the stock pilot/main jets. Ride in 45 to 90 degree weather. Any help would really be appricated.
Thanks

Put the pipe back on the bike and start with 170 main, 45 pilot, 3rd clip needle and 2 turns out on the screw. Should get you close.

[liquidivide300]

Matt,

got your replay however i want to keep the bike stock so when you mean pipe do you mean the rocket or the stock. stock is on it now and quiet which i like because i ride in an residential area to want to make my neighbors to mad.

thanks,
glen

[ohsobad_chevy]

Originally posted by liquidivide300
Matt,

got your replay however i want to keep the bike stock so when you mean pipe do you mean the rocket or the stock. stock is on it now and quiet which i like because i ride in an residential area to want to make my neighbors to mad.

thanks,
glen

I was thinking that you were going to put the aftermarket pipe back on. With the stock pipe, I am not for sure. Probably around a 45 pilot, 168 main and 2.5 turns out on the screw would put you pretty close.

[Backstabber]

We are going to tune my friend's YFZ this weekend. We ordered a special screw driver for reaching the A/F screw. I just wanted to double check and make sure we ordered the right tool. Your help would be much appreciated, thanks!:devil:

The tool is the "Motion Pro Pilot Screw Adjust." Its on motosport.com under tools and accessories.

[ohsobad_chevy]

Originally posted by Backstabber
We are going to tune my friend's YFZ this weekend. We ordered a special screw driver for reaching the A/F screw. I just wanted to double check and make sure we ordered the right tool. Your help would be much appreciated, thanks!:devil:

The tool is the "Motion Pro Pilot Screw Adjust." Its on motosport.com under tools and accessories.

You got the right one. I would have just ordered an adjustable screw instead of the bent screwdriver. The R&D remote fuel screw is awesome!!

[Backstabber]

Originally posted by ohsobad_chevy
You got the right one. I would have just ordered an adjustable screw instead of the bent screwdriver. The R&D remote fuel screw is awesome!!

Ok, great! Thanks for the reply!:devil:

[Pack]

Ok, I have many questions:

1: Concerning an air filter. I ride trails often. I ride in water, jump just a little, drag race, and dirt roads. What's a good one for me? Also, what's a good lid to go with? My stock one fills up with water often.

2. Should I find a jet kit somewhere to buy, or buy the jets seperately due to the price, even though I have no idea how to install them.

3. If I did buy them seperately, are they hard to install? How much would it cost to get them installed?

4. What's this "fuel screw" and where can I find it? Do I have to buy it? How's that whole thing work.

I live in Missouri, so the elevation jumps around, since there are hills everywhere. So, anything you want to add for extra advice, please feel free.

Thanks, guys.

[BrettOaktree]

i ride in similar conditions minus the water and i have a k&n with the pre filter, i like it, but i dont have my lid on so i dont have suggestions on a lid, and i think you should buy a jet kit just to get a good base, i got an fmf jet kit and it had really good instructions so it was kind of a jet kit for the average newbie like myself, and after that if u start doin more mods most of the time you only need to up your main jet so u can just buy those separately after some time, and id do it yourself its really not that hard to jet if you have good instructions and my fmf kit told me how to get to the fuel screw and how to adjust it.

But im wondering if my setup sounds alright to you guys?

Hmf sport series slip on, airbox lid off with a k&n and a prefilter, and the cam mod done

The elevation around here usually floats between 0-1000 feet depending on where i am, im looking for a good all year round setup the temps now are around 70-85 and in the winter the only time i go out is if its atleast 30. Right now im running a
48pilot
165 main
needle on the 3rd position
1 turn out on the fuel screw

feel free to leave your opinion, thanks

[quadboy-55]

Originally posted by Pack
Ok, I have many questions:

1: Concerning an air filter. I ride trails often. I ride in water, jump just a little, drag race, and dirt roads. What's a good one for me? Also, what's a good lid to go with? My stock one fills up with water often.

2. Should I find a jet kit somewhere to buy, or buy the jets seperately due to the price, even though I have no idea how to install them.

3. If I did buy them seperately, are they hard to install? How much would it cost to get them installed?

4. What's this "fuel screw" and where can I find it? Do I have to buy it? How's that whole thing work.

I live in Missouri, so the elevation jumps around, since there are hills everywhere. So, anything you want to add for extra advice, please feel free.

Thanks, guys.

ok, jets are probably one of the easiest things to install if you have patence to get the job done right because you have to try many different jets to get it right.

basically, there are two hose clamps on youre carburator on each end. loosten them and turn off your gas. then being on the opposite side of the quad (from the exhaust), pull the bottom of the carb closer to you. remove the tranny vent hose (grey hose with a spring on it) put it too the side and cover the hole with electrical tape. at the bottom of the carb you will see a nut (17ml) get a 17 ml wrench and slowly twist it off with a soda can under neath the carb with the top cut off. the gas will drain from the nut and make sure you get most of it in the can (thats why you put the electrical tape over the hole) once no more gas is comming out you can take off the nut. under the nut you will see two copper bolts with holes in them (these are youre jets) the big one that is closer to the nut you just removed is the main (the big one) furthur off to the side is the pilot jet. you can remove the pilot with a flat head, the main must be removed with a 7ml ratchet or screwdriver with a 7ml attachment. then screw the new jet inplace of the other jet and install your new pilot. reinstall the nut, hose, and replace the carb to its origonal position, tighen all clamps, and turn on the gas.

for the needle, on top of the carb (seat off) you will see a cover that says CR in big letters, it is held on with two allen screws, remove this cover. underneath (GAS OFF!! for the next part or you'll flood your bike) put you quad to ful throttle, this will pull the needle up. there is a silver allen bolt/needle cover you must remove, use a set of needle nose pliers once loosened to remove it. dont drop it down the carb. now you can see the part of the needle (NVCQ) that the e-clip goes onto, use the pliers again to pull the needle up and out (the needle isnt screwed on or anything besides the silver cap removed earler.) once the needle is removed you can replace it with the one that came in youre kit, once you put the e-clip on.. that is. (hint: try with youre new needle put the clip on the 3rd from top groove, that usually works best for most people) replace youre needle, put your quad to full throttle and screw in the silver allen retaning cap, then install the cover with the with the two allen screws.

the fuel screw is covered behind a metal plug you must drill through and pull out. then the screw is visable. turn it to adjust youre a/f ratio.




heres my quad so far.
mods: stock pipe, core removed, lid off, twin-air filter, Dynojet kit

main: 144
pilot: 42
needle: (NVCQ) 3rd clip from top
fuel scew: 1 turn out from seated.

[mxpimp2000]

im needing some help finding a 50 pilot jet.. i have 2 48's and only using 1 its a little lean right now anyone have a 50 to trade for 48?

my local dealer trades jets but dont have a 50

[ohsobad_chevy]

If you kind find anyone to trade, try jetsrus.com

:)

[mxpimp2000]

found one:D but i want to ask why my bike would need a 50 i dont see any ppl using 50's that seems high for a pilot jet.

i just recently cut out my airbox but still has the sides and bottom i just cut the rear out and the plastic around the battery box so the filter is pretty exposed gettin plenty more air than was. i havent messed with the main or needle or anything seems to run great except for 1/5 or 1/4 throttle in nuetral it cuts in and out and if u tapp it sorta fast no more than 1/4 throttle it cuts out and backfires:confused:

[Bdav450]

when you change jets do u need to leave the min jet adaptor in

[mxpimp2000]

http://www.youtube.com/watch?v=pdCuhPyTckE

[quadboy-55]

Originally posted by Bdav450
when you change jets do u need to leave the min jet adaptor in

only if you have a Dynojet or FMF kit!

keihin jets dont have an adaptor so there isnt one to swap. and there is no such thing as a main jet adaptor for Keihin jets.

[minerva]

Hey guys this is my first post, i need some help to correctly jet my 05 yfz wich i believe has the stock jet.

Stock engine
Pro circuit T-4 pipe
Quick Shot
K&N filter and K&N POWERLID
zip tie mod


Fuel 98 octane gas
Temperature 60º
Altitude sea level

What would you guys recomend for the main jet, needle and pilot jet has well for fuel screw turns. Thanks

[mxpimp2000]

i hear alotta people start at 168 main and 46 pilot. and 1 to 1 1/2 turns on fuel screw and just go from there determine if its lean or rich u can usually get it right within 1-2 sizes

[minerva]

Do you guys know any cheap online store that sell the jets? Thanks

[mxpimp2000]

rockymountain or jets r us

[follick]

i just got a M-7 V.A.L.E. from two brothers. i called their customer service to see what to run for jetting. they guy told me

2005 yfz 450

175 main.
stock pilot.
and clip all the way down on the needle.

i am running a UNI filter.

it hesitates. anyone have an suggestions?

thanks.

[quadrider2112]

07 yfz450 stock pipe tip removed no lid middle Arkansas so elevation varies i ride every weekend so temp varies 30-90
cuts out at 1/2 to3/4 throttle

165 mj
vitos custom needle 3rd clip pos from top
vitos fuel screw 2 turns out
too rich?:ermm:

[pharmboy]

I just bought a 2008 totally stock. I replaced the air filter with a K&N and went to a 162 main and a 48 pilot. That improved the cutting out when you punch it off idle but it's still seems lean. I haven't torn the car apart yet to see what clip the needle is on but I assume stock. I bought a 165 man and a 48 pilot today and was wondering what you guys thought my next move should be. Which to install first? It idles a little rough especially if I go from accelerating, pull in the clutch, and let it go down to idle. It might even stall. Then punching it from idle to 1/2, 3/4, or full it will usually cut out. Still sounds lean right? Thanks in advance for any help!

[quadrider2112]

i think your next step should be to pull plug and see what it looks like. That will give you an idea. Do you have your lid on or off? 48 may be a hair much to you may need 45. I just bought 45 for mine gonna try that.

lid off
fmf powercore4 slip on
cam mod
175mj
needle 2rd pos from top
vitos custom needle
vitos fuel screw 1 1/2 turns out
45 pilot


runs great need to pull plug to make sure but runs great.

[pharmboy]

I have my airbox on. I installed the 48 pilot and it works perfect.....but it is only 25 degrees here in Michigan. I assume I will need the 45 come summer. Is there an easy way to get to the plug?? Also is there an easy way to get to the carb needle without pulling the carb completely off? Thanks!

[quadrider2112]

I pull the tank cover and then take tank loose and just turn it sideways on the frame and leave gas line attached to check plug. I think that is as easy as it gets and this way you can blow the hole out b4 you pull the plug. The easiest way I know to mess with needle is to pull side skirts and take cable loose from throttle housing on bars. Then take loose air box and intake boot loose from carb. Then carb from intake on motor pull slack in cable. stand on shifter side turn top of carb to point at you and it should slide right out. 2 screws and a plug and your there. It might come out without removing side skirts but it is easier to just remove. [if you have stock needle only way to rich it is to shim it with a tiny washer] which will work my friend did it

[99warriorNJ]

LOCATED IN SOUTH JERSEY. ABOUT 250FT ABOVE SEA LEVEL

TRINITY SLIP ON
FCI INTAKE
GYTR JET KIT

180 MAIN
45 PILOT
#5 ON NEEDLE
2 1/2 - 2 3/4 TURNS OUT

STILL USING THE STOCK AIR BOX WITH SOME SLIGHT MODIFICATION TO THE BATTERY SIDE

[MNyzf]

is anyone running bigger starter jets? i am running a 165 main and a 45 pilot and when i burp the throttle it bogs then pops i have tried everything and it has to be that.....

[Pack]

Okay, so I want a general idea on what jets I need to run...

I have an '07 YFZ450, GYTR slip-on exhaust, GYTR K&N-style air filter with Uni filter vents in the lid, and I live in southern Missouri...

I bought these jets to start out:

170 Main
45 Pilot
Aftermarket fuel screw (not sure how many turns out I should have)
YZ needle (I'm assuming the middle position)
35 Leak Jet

... Should I buy more main jets around that area, or am I way off for where I'm located?

Also, I've heard both ways with a full system exhaust on a YFZ. Is it really necessary, or will I get just as much out of my slip-on since my header pipe's diameter is as large as it is?

Oh, and one more thing: Can I use any air filter cleaner and solvent on my air filter? Like, just buy something at O'Reilly's?

Thanks a ton, guys...

[quadrider2112]

your probably close to right on jets. I dont know bout the leak jet though. I want to change mine so let me know how the 35 works for you. I live in mid AR and run bout the same.

fmf power core4 slipon
cam mod
no lid
45pilot
175 main
2nd pos on vitos custom needle
vitos fuel screw 1 turn out
stock leak jet

only bogs if you stab it from an idle never bogs when im ridin.

as far as the filter i wood assume any k&n style filter cleaner will work. but if it were me i wood go to a foam filter. bout the only K&N style that filters at all is the fci its eight ply.

And as for the header im sure it will and power dont know how much but it will effect where the power is as far as low mid and high rpm

Hope that helps. let me know bout the leak jet. oh yeah do the cam mod its worth it

[Pack]

How much power gain do you get with the cam mod?

And how hard is it to do it yourself?

I'll let you know how the leak jet turns out. Thanks.

[quadrider2112]

It seemed to have gained power all over but a lot more pull from mid to top end. I have heard that you lose bottom end power with the cam mod but it seemed to give it power to me. I think the people that said that didnt jet right or something.

As far as how hard it is to do. I am a mechanic so i thought it was cake. I think if you have a lil know how and tools anyone can do it. Actually dirtwheels had there intern do it for the magazine just to show how easy it is. Just mark everything and dont drop the thrust washers from under the cam caps fall in the motor. YFZcentral has good pics of the whole process.

Clean your quad real good first:D

[Pack]

Well I'm not completely mechanically-stupid, I've done my fair share on old trucks. I've just never got into an engine before.

I think I may do this, though, and take your advice

[quadrider2112]

You will be glad you did. Just take your time and lay everything out in order. You will have to have an inch pound torque wrench though if you cant borrow one i would have it done elsewhere. gotta torque the cam caps. Read the yfzcentral instructions!:D

Never hurt to have a friend to hold the chain.

[jasonprox700]

I'm looking for a starting point on mine. I just installed a 98mm bb kit. The head has been ported and it has the +2mm titanium valves, taper bored carb to I believe 42mm, Web Cams, Rossier Full Exhaust, Curtis Sparks intake kit, and no air box lid.

I was thinking about starting out with a 180 or 185 main, a 48 pilot, 4th clip on the needle, and 2.5 turns on the air/fuel screw.

How does this sound? Does anybody have recommendations?

[Pack]

I'd start at 175 first, and go up from there. It's easier to tell you're too lean, than it is to tell you're too rich.

[Gommer450r]

please help i em goin crazy tryin to figure this out
i have hmf slip on hot caMS stage 1 k&n air filter with no lid stock box
i em at sea level
some people say i need 180 m but only got a 178 and take few days to order a 180 in but most people saY it would be way way to rich
i tried 42, 48pilot & 4th notch ncvq needle 2 to 3 turns air fuel 168.170.172.175.178 i find aounrd the 168 to 172 the bike works better but stumbles up top like 5th gear wide open and its nto the rev limiter i can power threw it and hit the limiter just like a miss like runnin out of gas for split second like a sputter
what do i do or go with
also my plug is a creamy paigy colour on the steel peice but the porcalin part is white

[mxpimp2000]

Originally posted by Gommer450r
please help i em goin crazy tryin to figure this out
i have hmf slip on hot caMS stage 1 k&n air filter with no lid stock box
i em at sea level
some people say i need 180 m but only got a 178 and take few days to order a 180 in but most people saY it would be way way to rich
i tried 42, 48pilot & 4th notch ncvq needle 2 to 3 turns air fuel 168.170.172.175.178 i find aounrd the 168 to 172 the bike works better but stumbles up top like 5th gear wide open and its nto the rev limiter i can power threw it and hit the limiter just like a miss like runnin out of gas for split second like a sputter
what do i do or go with
also my plug is a creamy paigy colour on the steel peice but the porcalin part is white

try a 45p seems like everyone with basic mods is gettn good results with it. i myself am about to try a 45p. 2-3 turns out on fuel screw is too much. ur suppose to get it within 1.25-1.50 turns if you go beyond 2turns out ur pilot is too small. go with a 175main and 3rd clip on the needle. if its too much gas go with a 172main if its almost right go 1 more clip down on the needle.

the fuel screw fine tunes ur pilot while ur needle fine tunes ur main. when ur screw and pilot are perfect it should start without having to blip the throttle. then focus on ur main jet and needle settings

[Gommer450r]

but wouldnt that be leaner tho
i needed to richen my plug but it sounds like i em rich up top either needle or main

[mxpimp2000]

An alternate way to figuring out if you're too lean or rich is to examine the spark plug. After a few seconds of full throttle running, quickly pull in the clutch and stop the engine (Do not allow the engine to idle or coast to a stop). Remove the spark plug and look at its color. It should be a light tan color. If it's white, the air/fuel mixture is too lean and a bigger main jet will have to be installed. If it's black or dark brown, the air/fuel mixture is too rich and a smaller main jet will have to be installed. While changing jets, change them one size at a time, test run after each change, and look at the plug color after each run.

After the main jet has been set, run the bike at half throttle. Any pinging means too lean. Blurbbing means too rich. Excessive smoking is also an indication of running too rich. As before, you can check the plug color. If it's white, lower the clip on the jet needle to richen the air/fuel mixture. If it's dark brown or black, raise the clip to lean the air/fuel mixture. Next go along slowly in one of the lower gears at less than 1/8 throttle and move the throttle quickly to 1/2 throttle. If the engine does not pull strongly. Sort of gasps for breath and only runs well after the RPMs build up, it is an indication that the needle is too lean.

[Gommer450r]

okay thanks ill try that out tomorrow thanks alot hopefuly this helps

I have a 06 yfz450 with DG Xcellerator exhaust. Any i deas where to start. im in Indiana. Also no airbox lid. Thanks.

[stevestauff]

does anybody here have a florida setting ?ihave a whitebrothers slip on thats it any recs oh and lid off.

[quad4114]

48 pilot 178 main 4th clip down on needle prodesign air filter with no lid and r & d bowl on carb 100 octain fuel

[yfzrider690]

I just had mine dynoed at craze deals in winchester bay two weeks ago. I have a mmad port job, mmad warpspeend intake cam, cam mod, 12.5:1 piston, yoshi rs-7 full exhaust, modquad adapter with k&n. I am running a 170 main, 45 pilot, 3rd clip on the ncvq needle and 2 turns on the a/f screw.

[stevestauff]

well what did it dyno at.

[yfzrider690]

It dyoned at 48hp and 32 tq. It was done at craze deals in winchester bay, he said a stock yfz does 33 on his dyno and his dyno reads around 3hp low.

[stevestauff]

they showed a yfz dyno at that with cam mod. exhaust and the lid off without porting and stuff.

[yfzrider690]

Originally posted by stevestauff
they showed a yfz dyno at that with cam mod. exhaust and the lid off without porting and stuff.

Who showed that? A dyno is just a tuning device and everyone reads different. So just cause one shows 48 doesn't mean he would get that on another dyno. I bet on the same dyno he would be around 40. Everyone gets so caught up by what there quad puts out. I can tell you I was in Florence a couple weeks ago and no other 450 with just exhaust and filter could even come close. So what does that tell you???

[minerva]

..

[minerva]

Hello guys i need some help, i have a 2005 yfz with pro-circuit t4 slip-on, K&N air filter, K&N power lid, quickshot and i also got the tie mod on the carburator. Recently i bought the dynojet kit for my bike and i mount it just like the instructions say: Mainjet 144 needle on groove # 5, dyno pilotjet 48, also 1.5 turn, sea level but the byke fails in midle to high rpm i tried the 160 main and it´s worse and also tried the 150 but it´s the same thing, so i believe that it has too much gas and was wondering if going up a groove on the nidle is the correct thing to do or if i should trie a smaller main jet or even close a bit the gas screw. Thanks

[minerva]

Anybody????

[yfzrider690]

If i were you I would junk that jet kit and go to the dealer and get some keihin jets and the ncvq needle or use the stock needle. With the keihin jets you should be running around a 45 pilot, 165-168 main jet and 3rd or 4th clip down from the top on the needle and 1 1/2 turns on the a/f screw. Jet kits are junk in my opinion, I have only ever bought one and I ended up using nothing out of it.

[minerva]

Originally posted by yfzrider690
If i were you I would junk that jet kit and go to the dealer and get some keihin jets and the ncvq needle or use the stock needle. With the keihin jets you should be running around a 45 pilot, 165-168 main jet and 3rd or 4th clip down from the top on the needle and 1 1/2 turns on the a/f screw. Jet kits are junk in my opinion, I have only ever bought one and I ended up using nothing out of it.

You may be right but since i bought the kit it will have to do. So today i put nidle on the 4th groove and the bike is runing great without the K&N powerlid but when i put the lid on it fails in mid gas, Any ideas? Maybe turn a litle bit the screw?

[99warriorNJ]

Originally posted by minerva
You may be right but since i bought the kit it will have to do. So today i put nidle on the 4th groove and the bike is runing great without the K&N powerlid but when i put the lid on it fails in mid gas, Any ideas? Maybe turn a litle bit the screw?

leave the lid off.. more air more power.. you should ditch the intake setup you have now and get a Fuel Customs Intake. they are pricey but well worth it for the added power they deliver. if you do happen to go that route.. get a 180 keihin main, 45 pilot, 4th clip, 2.5 turns out.

[minerva]

After another try i guive up, i took the bike to a local diller and hoppefully they will make it up...

[ohsobad_chevy]

Originally posted by minerva
After another try i guive up, i took the bike to a local diller and hoppefully they will make it up...

Why did you give up. You won't ever learn by letting someone else do it for you. Jetting is not hard once you learn how to "hear" the motor.

[minerva]

Originally posted by ohsobad_chevy
Why did you give up. You won't ever learn by letting someone else do it for you. Jetting is not hard once you learn how to "hear" the motor.

Yup you are right but i simply lost my pacienc to pull my carb apart, i have changed the main jet 6 times, pull the nidle off 3 times, and open and close the gas screw several times.... Probably my next bike will have electronic injection like all the new ones, so probably (but unfortunatly) i don´t need the knowledge. Anyway i bought the kit for 50$ with postal serviçe from ebay plus +- 70$ for hand laber so i ended up winning, here in Portugal the cheapest you can get the dynojet kit is about 150$. By the way nice forum you guys have. Regards and thanks for the help

[SDRIDER15]

MY GIRLFRIEND HAS A 2006 YFZ450 QUAD. AND IM HAVING PROBLEMS WITH GETTING IT RUNNING RIGHT. IT BACK FIRES A LOT AND WILL DIE OUT WHEN YOU PUNCH THE GAS FROM IDLE. IM GOING TO CHANGE THE JETTING TODAY AND WAS WONDERING IF I COULD GET SOME POINTERS.

*ENGINE IS STOCK
*K&N AIR FILTER WITH AIR BOX LID OFF
*STOCK PIPE WITH SPARK ARRESTER REMOVED.

I WAS GOING TO CHANGE THE JETTING TO 165 or 168 MAIN, 45 PILOT AND THE REST STOCK. WHAT DO YOU THINK THE JETTING SPECS SHOULD BE FOR THIS SET UP?

THANK YOU FOR YOUR HELP.

[yfzrider690]

Originally posted by SDRIDER15
MY GIRLFRIEND HAS A 2006 YFZ450 QUAD. AND IM HAVING PROBLEMS WITH GETTING IT RUNNING RIGHT. IT BACK FIRES A LOT AND WILL DIE OUT WHEN YOU PUNCH THE GAS FROM IDLE. IM GOING TO CHANGE THE JETTING TODAY AND WAS WONDERING IF I COULD GET SOME POINTERS.

*ENGINE IS STOCK
*K&N AIR FILTER WITH AIR BOX LID OFF
*STOCK PIPE WITH SPARK ARRESTER REMOVED.

I WAS GOING TO CHANGE THE JETTING TO 165 or 168 MAIN, 45 PILOT AND THE REST STOCK. WHAT DO YOU THINK THE JETTING SPECS SHOULD BE FOR THIS SET UP?

THANK YOU FOR YOUR HELP.

The jetting that you suggested should be real close. I would put the 165 in since you don't really have anything done except the K&N.

[SDRIDER15]

yeah i put the 168 and 45 pilot on last night and it was too much for it. still backfired and cut out.

ill put the 165 in and see how she runs!

thanks for the input!

[SebYfz450]

Hello everyone i got a 07 YFZ 450 Everything stock on it soon i'm going to buy a Full System HMF Competition serie exhaust and a Competition kit (Basic Jet Kit, K&N Air Filter, Outerwears) The website Recommended Jetting is 175 Keihin Hex, 48 pilot Should i stick to that? I mostly ride in trail and like 1-2 times per weeks on the track i'd like to Know what would be the best jetting for my bikes.

[cmradn213]

i have a 2008 yfz450 with a fmf powercore 4 and stainless steel mega bomb header. my air filter is a K&N with outerwears pre filter and air box lid is ON im not sure on my elevation but temperatures when i ride range from 60 to 90 degrees prolly an average of 72-75 degrees i had the dealer jet my quad before i had the k&n and mega bomb and im not sure what the jet settings are its cold here right now so its tough to tell if i need to adjust things if anyone could help it would be appreciated thanks

[trent zimmerman]

I have two yfz450's,one'04,one'05,both have HMF sport slip on's,old style,with quiet cores,velocity air filters with outerwears,EHS lid,and boyeseen quickshot 2's,HMF recomended 165 main and 48 pilot,but no needle clip position or how many turns out on air/fuel mixture screw,live in Thurmont Maryland,elevation 518',but my son races in the East Coast XC series in West Virginia,where the track elevations range from 960' in Morgantown Wv to 1930' feet in Elkins Wv.Any help,recomendations,guidence etc.would be greatly appreciated,thanks in advance.

[minerva]

Hey guys i need some help, i have a 2005 yfz stock engine with dynojet main 128 pilotjet 48 4th clip on the needle, quickshot, prodesign, kn filter and kn power lid, pro-circuit slip on, 2/15 on the air fuel screw but my bike still bogs, could it be the leak jet? What is the stock size and what size should i buy? Thanks

[ApexJoey]

New to this site and this is the best yfz450 jetting thread I found. Need some serious help with mine. It's back firing a lot on deceleration, even when letting go of the throttle after revving a little in neutral, and bogging out at 3/4 to WOT when riding. It doesn't fall flat on its face but it bogs down a bit before it catches. Cold starts with it aren't the best either, it takes awhile and gets to the point where it drains my battery out after 4 or 5 cold starts. I'm hoping its a jetting issue and any help would be much appreciated.

Sparks Racing full Exhaust
K&N air filter with lid off
Im in Long Island Ny and its around 30-40 degrees right now

i haven't opened up the carbeurator yet so I don't know what sizes are in there.