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Pappy
02-13-2004, 04:00 PM
anyone wanna explain the steps needed to jet this puppy:confused: and possibly fill us in on what jetting has been working the best?

trueblue450
02-13-2004, 04:22 PM
whats a jet???? :confused:

Maxx_Action
02-13-2004, 04:32 PM
Well...

I will say this, this thing likes to EAT! I find that if you try to read the plug, it will starve. I was always taught as a young motorhead that the plug should be a nice greyish brown color. If you run the YFZ like that, IMO, you are losing HP. I also think that the hyperactivity of the accelerator pump on the FCR carb can throw off the plug reading a little bit cause that thing really dumps when you punch it. Mine runs best right now with a 178 main (cause it's cold) I am running the NVCQ needle on the 4th clip, a 48 pilot at about 2 and 1/2 turns. When it gets warmer again I will prbably be back to a 172, 45 pilot, 3 turns, or somewhere close. I also run the Ron Wood intake which flows MUCH better than the stock boot. A hundred and fity bucks well spent on that mod.

Most people Jet it up til it's too rich (it will kinda blubber and fizzle on top before it hit's the limiter) then jet it back down 2 steps and that is a good guideline. Good luck...

Maxx

Cron
02-13-2004, 04:46 PM
Maxx Action what mods do you have done? All I have done is a pipe and my main jet is a 165 now and it hits the top end quick. It makes me think I am too lean if you are running a 178! Should I try a 168? I thought the 165 was perfect but now it seems too low. I hit the top end fast, it does backfire on the decel sometimes though. You are from IL right?

Cron
02-13-2004, 04:49 PM
O yea i forgot to add I have a 45p, GYT-R Needle 3rd clip and my fuel screw is about 2 1/2 maybe 2 3/4

Maxx_Action
02-13-2004, 04:52 PM
Originally posted by Cron
Maxx Action what mods do you have done? All I have done is a pipe and my main jet is a 165 now and it hits the top end quick. It makes me think I am too lean if you are running a 178! Should I try a 168? I thought the 165 was perfect but now it seems too low. I hit the top end fast, it does backfire on the decel sometimes though. You are from IL right?

Check the Sig...

for mods. The jetting thing, if it gets above 30 degrees, I gotta go back down or she gets a little lazy. Remember, I am runnin the Wood intake which is a 42 mm straight tube from the filter to the carb so it flows like mad, plus the K&N which increases flow as well. I think you may be able to go up on size, maybe two and you would see some more balls on top...

Maxx

Maxx_Action
02-13-2004, 04:58 PM
P.S.

The cam mod also makes her want to eat a little more, and as soon as it warms up you should be fine wehre you are plus one clip position on the needle. When I first got this quad, I had the GYTR pipe, no lid, 42 pilot, GYTR needle 4th clip, and a 165 main. When I went to the K&N I went to a 170 and it ran great, when I added the Cam mod, 172, then with the Wood intake, I am guessing a 175-172 depending on temp. I haven't had a chance to really run it that much since I got the Intake for Christmas, I guess I would know if it would EVER GET FRIGGIN WARM!!!!


Maxx

Bad Habit
02-13-2004, 06:15 PM
This past fall at Sand Fest in OK, I talked quite a bit with the guy camped next to me. He had the Ron Woods intake and the exhaust (still in developement, wasn't even coated yet) and he told me alot of things about jetting a four stroke. He was somewhat of an "old timer" and had some very simplistic approaches to jetting. One thing that stuck out to me was that he stated that if you crack the throttle wide open while setting still, it should puff out some black smoke. If it doesn't, it's too lean. He also said that it was really hard to read a plug on a four stroke when compared to a two stroke. In fact, he said that he would put just a tad of 2 stroke oil in the gas tank of a four stroke when trying to get the jetting ironed out. He said that it made the plug color easier to read. I was inclined to believe him cause noone could touch his YFZ that whole weekend on the drags. And he had a DS650 that was one of the fastest bikes there, two or four stroke.
Has anyone else heard of these rules of thumb or was this guy just full of it?

RiPPiNiTuP7
02-13-2004, 10:54 PM
lots of good info:

http://www.eskimo.com/~daddog/index.htm

xcyfz450
02-15-2004, 12:19 PM
i have a yfz 450 with just a hmf slip on and no lid and i was told to run a 180 main jet is that right? plus mine also backfires on decel can anyone steer me in the right direction if this is correct or what i need to do thanks

Maxx_Action
02-15-2004, 12:58 PM
Originally posted by xcyfz450
i have a yfz 450 with just a hmf slip on and no lid and i was told to run a 180 main jet is that right? plus mine also backfires on decel can anyone steer me in the right direction if this is correct or what i need to do thanks

Stock Pilot is a 42. Go to a 45, at somewhere between 21/4 to 3 turns should solve the pop on decel.

Maxx

xcyfz450
02-16-2004, 11:27 AM
thanks maxx action for your info for my next probleb there is a big dead spot when you get on the gas 180 main 45 pilot and 21/2 turns out thanks for any additional help

Maxx_Action
02-16-2004, 11:58 AM
Originally posted by xcyfz450
thanks maxx action for your info for my next probleb there is a big dead spot when you get on the gas 180 main 45 pilot and 21/2 turns out thanks for any additional help

HEy...

if you are talking about setting and idling and punching it, that won't go away. That is cause the FCR carb has an extremely active accelerator pump which shoots a big blast of fuel when you hit the gas. When you do it under load, E.G. rolling along the trail, it won't do it cause the vacuum at intake is increased because of the load on the engine, but when sitting still it kinda goes BWALLHH PAHP! Just normal...

Maxx

xcyfz450
02-16-2004, 12:03 PM
its when im like at 1/4 throttle and roll into it hard it goes blah i dont think it should do that ive also been toon to turn my air screw almost all the way in and ive heard to move the clip on the needle i dontknow what to do thanks again

Maxx_Action
02-16-2004, 02:53 PM
Originally posted by xcyfz450
its when im like at 1/4 throttle and roll into it hard it goes blah i dont think it should do that ive also been toon to turn my air screw almost all the way in and ive heard to move the clip on the needle i dontknow what to do thanks again

If you move...

the needle position, it will be too fat with a 180 main. You will need to go down a jet size or two for every clip of the needle that you move up. As far as the dead spot in the throttle, that has me puzzled. Are you sure you are out 2&1/2 turns on the fuel screw? If not, gently turn it all the way in. Note the handle on the screwdriver and turn the screw out 1/2 turn at a time until you reach 2&1/2. Other than that, I am a little unbsure...

Maxx

CatMostFeared
02-17-2004, 03:08 PM
I have the HMF pipe, cammod ,NVCQ needle and stock airfilter.
170 main ,45 on the polit,needle on 2nd clip from top

02-17-2004, 03:14 PM
I have found jetting to be over rated.

Just take the stock main jet and small drill bit don't matter the size really and ream it out a little. You will be fine!!!!!!

That's what I did with mine and seems to be running just fine.

Another goodbreak in tip. Run 4 GNCCs ride tons at your house. then go run the 12 hours of america then come back and ride a little more before you change the oil the first time.

CatMostFeared
02-17-2004, 03:23 PM
Originally posted by GNCCer

Just take the stock main jet and small drill bit don't matter the size really and ream it out a little. You will be fine!!!!!!



:huh :eek2: :huh :eek2:

02-17-2004, 03:29 PM
let me guess your one of those people that took several different jets and tried them. payed attention to how each one affected your quad. and made your decesion on what jet combination to use?

all un-necesary work!!!!!!

CatMostFeared
02-17-2004, 06:42 PM
nope I just let everyone else do all the work and do what sounds best.I got it real close and only made one change.
I could just read the spark plug. I wish I had your luck

02-17-2004, 06:51 PM
Marty I am jsut messing around Kinda.

CatMostFeared
02-17-2004, 06:53 PM
:D

660bigdaddy
02-18-2004, 02:27 PM
NVCQ needle and stock airfilter.
close to my setup.
45 pilot
2 1/2 turns on air screw
170 main
4th clip
no lid (yikes)
mine seems a little rich. even with the lid off. i'm concerned cuz when i put the lid on, it will really be fat.
any suggestions?
i was concidering getting a outerwear airbox cover.

CatMostFeared
02-18-2004, 06:20 PM
Drop the needle down one

660bigdaddy
02-19-2004, 07:21 PM
thanks marty. see ya in georgia.:D

powerstroke
02-28-2004, 08:05 PM
anybody have trouble with their bike acting very lean in the total stock setup? just picked my bike up. its all stock. havent touched anything. idle is erratic and the idle screw doesnt seem to affect the idling circuit much. its either idling really slow or REALLY fast(which in my experience reflects a lean pilot condition). tonight i was messing with the idle screw trying to get it to idle and i looked up and the headpipe was cherry red. YIKES! so i just quit on it until i can pick up some mains and pilots and start from scratch with my hmf slip on I have on hand already. a very relaible pro racer told me with the hmf slip on and airbox lid off that 180 main and 45 pilot with air screw 2.5 turns out and needle clip moved down one position should get me very close. I guess we will see.......Matt

Maxx_Action
02-28-2004, 08:19 PM
Originally posted by powerstroke
anybody have trouble with their bike acting very lean in the total stock setup? just picked my bike up. its all stock. havent touched anything. idle is erratic and the idle screw doesnt seem to affect the idling circuit much. its either idling really slow or REALLY fast(which in my experience reflects a lean pilot condition). tonight i was messing with the idle screw trying to get it to idle and i looked up and the headpipe was cherry red. YIKES! so i just quit on it until i can pick up some mains and pilots and start from scratch with my hmf slip on I have on hand already. a very relaible pro racer told me with the hmf slip on and airbox lid off that 180 main and 45 pilot with air screw 2.5 turns out and needle clip moved down one position should get me very close. I guess we will see.......Matt

Sounds...

like you are on the right track, and yes it is very lean from the factory. I think it is a 155, needle on 4th clip, 42 pilot at about 2 and a quarter turns is where mine was. It's not too difficult to get right. Good luck...

Maxx

660bigdaddy
02-29-2004, 07:03 AM
looked up and the headpipe was cherry red. YIKES!
the stock head pipe is not coated. if you let it sit and idle no matter how perfect your jetting is, the pipe will turn red. don't go by the pipe. but yes the stock setup is a joke. way lean, and runs like crap. jmo:D

AlaskaSpeed
02-29-2004, 11:18 AM
178 main
48 pilot
2.5 turns on mixture screw
Hetrick pipe
13:1 piston
cam mod
K&N airfilter; no lid
120 octane
Vortex X10 cdi
...sitting right about sea level......

powerstroke
02-29-2004, 07:24 PM
I havent torn into mine yet but i was told that my keihin pilot jets that i have for my 400ex's will NOT work in the yfz carb?? I didnt know keihin had more than one type of pilot jet......so what do i ask for??? fcr pilots????? Matt

hicksd
02-29-2004, 07:31 PM
Not just FCR pilot jets, but 2004 YFZ450 pilot jets.

jlhughes750
03-05-2004, 08:20 PM
168 main
45 pilot
ncvq(yz) needle in the middle position


Pappy, that should be a great place to start... and finish!!!!
I've seen,talked to and worked on a ton of these the last 2 months w/ ECATV....these are not their specs, there mine, I've seen what others used and ridden those bikes. The best response with smooth power roll is with this jetting..



This should work with any pipe unless its set up for dragging only.
I'm usin a Dr.D pipe, K&N, and Pro Flow with the lid on....

Crazy Honda
03-06-2004, 12:47 AM
Originally posted by jlhughes750
168 main
45 pilot
ncvq(yz) needle in the middle position


Pappy, that should be a great place to start... and finish!!!!
I've seen,talked to and worked on a ton of these the last 2 months w/ ECATV....these are not their specs, there mine, I've seen what others used and ridden those bikes. The best response with smooth power roll is with this jetting..



This should work with any pipe unless its set up for dragging only.
I'm usin a Dr.D pipe, K&N, and Pro Flow with the lid on.... what about your air mixture screw?

jlhughes750
03-07-2004, 04:57 PM
air screws at 2.5