tired of this D**N yamaha someone help

[mxpimp2000]

i just recently had my bike rebuilt with a new cylinder, wiseco 13:1 piston changed the exhaust from a tc full to a hmf slip. the jetting is 168 main, 48 pilot jet.

my problem starts at 1/4-full, it will start fine idle great but if u give it gas over 1/4 throttle it starts cuttin out and backfires then if u punch it like u wanna blast out of the holeshot it dies. from 1/2 throttle to full when u punch it its got a dead spot or hesitation sometimes it will die when u punch it sometimes it wont it will die every time if u punch it from 1/4 to full

i called the guy who built it and he says my jets are clogged so i clean them still nothing....so i changed the spark plug...still nothing...WTF is up with this JUNK!!:grr: :grr: :grr:

[jason_david1]

im not a jetting expert but i think your pilot is to big. try a 42

[mxpimp2000]

but it ran like a champ b4 i had it rebuilt it just had a different exhaust on it then

[jason_david1]

call hmf and they should be able to give you a starting point

[mxpimp2000]

could it be anything else rather than jets???:huh

[jason_david1]

i wouldnt think so. sounds like carb trouble to me

[mxpimp2000]

im fed up with it i cant get ahead with it for nothing i had to pay 730 dollars for gettin it rebuilt and im broke as hell now i cant even buy jets to try anything different

check your timing,, maybe you throttle switch on your carb is junk, unplug it and see what happens, not the tps, but the other switch.

[Ride1Rob]

First, it's nothing major so cheer up. It's not like you took it out on the first ride and you heard a loud CLUNK and instant rear tire lock lol. And if I can remember, your piston was stock before. Going to a hc piston as well as another exhaust will change your jetting quite a bit. YOU HAVE TO DIAL IT BACK IN ;) . Rule of thumb is to change one thing at a time and see how the bike performs. Where is your needle?

[mxpimp2000]

when i got the quad back from the shop it ran good but i never punched it out like i am now bcuz it hadnt been broken in yet i had rode it around real easy like for 15 mins at a time for about 1hr and the heat cycles of course but now that its time to give it hell i cant, but if i ride it and i use the clutch right i can get it past the dead spot and get it wide open its like u got to trick the hesitation or bogg by using the clutch to get it wide open, if im just crusing around and try to mash the throttle wide open it will striaght up fall on its face and die no matter what throttle position ur giving it unless u use the clutch to get passed that point:eek2:

[mxpimp2000]

Originally posted by Ride1Rob
First, it's nothing major so cheer up. It's not like you took it out on the first ride and you heard a loud CLUNK and instant rear tire lock lol. And if I can remember, your piston was stock before. Going to a hc piston as well as another exhaust will change your jetting quite a bit. YOU HAVE TO DIAL IT BACK IN ;) . Rule of thumb is to change one thing at a time and see how the bike performs. Where is your needle?

well i took the jets out and it had a 168main and 48 pilot what do u suggest? it also has stock non adjustable needle.

mods list:
hc 13:1 piston
HMF slipon
UNI filter
cam mod
no box lid
148 main
48 pilot

[Ride1Rob]

Go to a 45 pilot and get rid of the stock needle and get a NCVQ. The bike seems to not be dumping enough fuel when you're on the throttle. The NCVQ will let you play with the different positions to dial it in.

[mxpimp2000]

hook me up with those lol i have no hook up around here man its like 20 bucks for jets around here

[Ride1Rob]

Don't have an extra needle but I'll see what jets I can get you. Have a whole heep. Let me know what jets you have mains and pilots. Will see if I can find a NCVQ and link you to it.

And another thing, NEVER IN YOUR LIFE CALL ANOTHER YFZ A PIECE OF JUNK! I don't care if it's burnt up on the side of the road with Honda stickers on it :mad: . lol

[mxpimp2000]

Originally posted by Ride1Rob
Don't have an extra needle but I'll see what jets I can get you. Have a whole heep. Let me know what jets you have mains and pilots. Will see if I can find a NCVQ and link you to it.

And another thing, NEVER IN YOUR LIFE CALL ANOTHER YFZ A PIECE OF JUNK! I don't care if it's burnt up on the side of the road with Honda stickers on it :mad: . lol

lmao...ok sounds kool man i dont have any jets at all no mains or pilots just a 48 and 168

[#17YFZRACER]

if u say its fine to 1/4 your pilot is fine. u need an NCVQ and pick it up at least 2-3 positions from the bottom. the main is nothing more than 3/4-wot. the needle is middle. u need to "fatten" it up a little by raising the needle in the carb. u do need to get a NCVQ with your mods:eek2:

[mxpimp2000]

Originally posted by #17YFZRACER
if u say its fine to 1/4 your pilot is fine. u need an NCVQ and pick it up at least 2-3 positions from the bottom. the main is nothing more than 3/4-wot. the needle is middle. u need to "fatten" it up a little by raising the needle in the carb. u do need to get a NCVQ with your mods:eek2:

ill give it a try when i get one i guess

[Ride1Rob]

But that's really fat for a stock motor other than a hc piston. Does the bike fire right up (when cold) when you crank it? If there is no bog as soon as you touch the throttle it's okay. But that needle is the root to your problem. You need to go up a point or two on your jets as well. I have a 170 and a 172 I'll send ya.

[mxpimp2000]

it fires up good with choke on if its cold outside and idles good to.
Ride1Rob email me mxpimp2000@yahoo.com

[ohsobad_chevy]

Originally posted by mxpimp2000

mods list:
hc 13:1 piston
HMF slipon
UNI filter
cam mod
no box lid
148 main (I am assuming you meant 168)
48 pilot

With the mods you have listed (I don't know what your elevation is, but I am assuming its around 600-1000 ft......like where I am)
You definitely need the NCVQ needle!! I would run it on the 3rd or 4th clip position from the top. (there are 7) Put at least a 172, possibly a 175 with these colder temps and a 45 pilot.
Also, do you have an adjustable fuel screw? 2.5 turns out on the screw.

[mxpimp2000]

it has a fuel screw i was told i aint messed with it to see if the bowl had been drilled out for it but my elavation is 537 feet above sea level

[ohsobad_chevy]

Originally posted by mxpimp2000
it has a fuel screw i was told i aint messed with it to see if the bowl had been drilled out for it but my elavation is 537 feet above sea level

Not being rude here at all, but this is why your bike is running poorly. You have to tune your bike to run with modifications.
You have the stock non adjustable needle and your not sure about the fuel screw. I would suggest getting an adjustable fuel screw (R&D flex is awesome) -$30 shipped to your door. and the NCVQ needle. -$17 to your dealer, 170-175 main jets and 42 and 45 pilot jets. -$30 or so. (jetsrus.com)

Again, I am not trying to be an arshole, just trying to help.
And!!!!!! Like R1R said, DON'T EVER CALL A YFZ A POS!! :macho

[mxpimp2000]

the guy that jetted my bike told me he put the fuel screw in it but i have not messed with it,

[Jason Hall]

I would think even a 175 main would be small. Your temp In Ohio Is probly damn Cold. When I jetted a buddys yfz, I removed the airbox lid removed the exhaust end cap, and did the exhaust cam mod. I ended up with a 185 main In his In this cold Michigan weather. I wound up with the stock needle 1 click from the bottom (Rich). His bike wanted Fuel!!! It won't hurt you to bump the main and see If It helps It. I absolutly hate working on the carb on the YFZ because of the top motor mount cross member on the frame. I don't think getting on here calling the bike junk will help any LOL. I know what It's like to get pissed, but It's not the bike's fault. You need to give It what It wants. Good luck. Your problem sounds exactly like the one I jetted. It would not rev out, It was backfiring & popping like mad. I bet your still WAY lean. I know the HMF pipes are very free flowing, and that alone Is enough to mess up your jetting. I would for sure Invest In an adjustable needle.

[#17YFZRACER]

u say u think u have a screw in it:huh look at the bottom of ur carb and see if there is a screw coming out the bottom. it will more than likely be colored and have #1-4 on it. im not trying to be an @ss but you know ur problem is getting and ur not sure if it has a screw. kinda funny lol. c if u have 1 if not they are cheap.

[mxpimp2000]

Originally posted by #17YFZRACER
u say u think u have a screw in it:huh look at the bottom of ur carb and see if there is a screw coming out the bottom. it will more than likely be colored and have #1-4 on it. im not trying to be an @ss but you know ur problem is getting and ur not sure if it has a screw. kinda funny lol. c if u have 1 if not they are cheap.


yall people not understand i dont do the work on my bike i pay my mechainc to do that. but the way the economy is right now iam not flowing with money to pay him fix it again therefore im tryin to learn as much as possible to have the knowledge to start doing my own work so that i know exactly what my bike has and dosent have. yall assume iam a complete dumba** bcuz i dont know alot bout carbs thats why i ask ?'s and learn as i go :D

[jersey devil]

From all I'am reading here everyone is trying to help you and in fact alot of the guys are willing to go out of there way to help you so you need to chill and believe me they aren't treating you like you are dumb!
Calm down and like one of the guys said it is only a jetting problem which believe me my friend just finding that out should be a great relief to you.I realize you don't turn wrenches so sometimes it is hard to comprehend what everyone is telling you about this carb jetting.Doesn't make you a bad person or dumb so just take it lightly and listen to these guys because they are only trying to help a fellow rider.
Thats what this forum is about.Good luck!

[ohsobad_chevy]

Originally posted by mxpimp2000
yall people not understand i dont do the work on my bike i pay my mechainc to do that. but the way the economy is right now iam not flowing with money to pay him fix it again therefore im tryin to learn as much as possible to have the knowledge to start doing my own work so that i know exactly what my bike has and dosent have. yall assume iam a complete dumba** bcuz i dont know alot bout carbs thats why i ask ?'s and learn as i go :D

I, nor anyone else was calling you dumb. We were all new at jetting at one point, but hey, thats how you learn. We encourage you to ask questions and we will do our best to help you out, but at the same time, we need your help too.
What you really need to do is familiarize yourself with your quad. Learn what each component is and it's function.
You need to buy the necessary jets, needle and an adjustable fuel screw.
Let me know when you have the necessary items........in the mean while, check your PMs.
;)

[mxpimp2000]

Originally posted by jersey devil
From all I'am reading here everyone is trying to help you and in fact alot of the guys are willing to go out of there way to help you so you need to chill and believe me they aren't treating you like you are dumb!
Calm down and like one of the guys said it is only a jetting problem which believe me my friend just finding that out should be a great relief to you.I realize you don't turn wrenches so sometimes it is hard to comprehend what everyone is telling you about this carb jetting.Doesn't make you a bad person or dumb so just take it lightly and listen to these guys because they are only trying to help a fellow rider.
Thats what this forum is about.Good luck!

and i appreciate all the help thats why i come to the forums daaily and get alot of info and everything. i know alot bout quads i just dont know much on 4strokes internal engine parts or the carbs. im a 2stroke junkie and new on 4stroke motors as of april 08 so im gettin alot of info off the site and learning more about them to where i dont have to pay someone arm and leg for labor fees. all of u guys help alot and i know some go out of there way to further help me like ROB and i appreciate it a ton. im here to help as well as you are. i will have to get a needle and air screw for my carb sometime i get a chance to

[ohsobad_chevy]

Originally posted by mxpimp2000
i mean id like to know a 110% what my problem is thats why i ask ?'s and ive heard things like too rich/ too lean/ jetting/ timing/ sprkplug/ etc etc i dont wanna go buy something i dont need if thats not my problem people tell me soo much gulosh idk who is right!

and yes my bike has a air screw no need to buy one

For us to tell you exactly what the problem of your bike is would be impossible. All we can do is point out some of the things that you need to check.
Judging from your current jetting, altitude, and colder winter temps currently......your jetting is the culprit.
However, it could be a combination of the things that you listed above, too.

We have done all we can do. What we need for you to do is to start checking the things that you have listed above and omitting the problem. As R1R stated, you need to diagnose one problem at a time.

Since you havent got the required jets yet, you can begin to check the other things that could be wrong.

I PM'd you a copy of the service manual for the YFZ.

[mxpimp2000]

i understand i dont care about the jettin for the cold weather because im not goin to ride until racing season is here and temps around here are usually 70s 80s and 90s when i ride or race

[ohsobad_chevy]

Originally posted by mxpimp2000
i understand i dont care about the jettin for the cold weather because im not goin to ride until racing season is here and temps around here are usually 70s 80s and 90s when i ride or race

OK, then start by checking your valves, timing, spark plug, etc.

[mxpimp2000]

Originally posted by ohsobad_chevy
OK, then start by checking your valves, timing, spark plug, etc.

motor is FRESH not even 1 hour on motor total valves are in spec spark plug is new timing idk i havent pulled that

[ohsobad_chevy]

Originally posted by mxpimp2000
motor is FRESH not even 1 hour on motor total valves are in spec spark plug is new timing idk i havent pulled that

Start by pulling the valve cover off and checking the timing.

[mxpimp2000]

Originally posted by ohsobad_chevy
Start by pulling the valve cover off and checking the timing.

as soon as i get chance to i will try that but its 20 degrees here and no heater in shop lol

[Ride1Rob]

His biggest mistake was getting the bike from his mechanic without it running properly. When I rebuild for guys here I do the break in, check for any possible problems, ride the bike hard so that EVERYTHING can be dialed in when it's picked up. Once that's done I have the guy to come and test it. When it goes home they know what they're getting and I know what left my garage.

[ohsobad_chevy]

Originally posted by Ride1Rob
His biggest mistake was getting the bike from his mechanic without it running properly. When I rebuild for guys here I do the break in, check for any possible problems, ride the bike hard so that EVERYTHING can be dialed in when it's picked up. Once that's done I have the guy to come and test it. When it goes home they know what they're getting and I know what left my garage.

Exactly!! :)

Come to think of it, my bike has never jumped time, but my buddies LTR jumped one tooth on the intake cam and wouldn't even start. I wouldn't think that a YFZ would even start with jumped timing, but I would still go ahead and check the timing and the cam chain tensioner as well.

In addition to the spark plug, I would also check your intake and exhaust over real well, make sure there isn't any leaks anywhere. ;)

[mxpimp2000]

as of today im thinkin its gettin too much gas because when i got to start it it takes a while and if i push the gas any it just backfires and esp if i turn the choke on. idle it runs fine but the further i push the gas in nuetral it will just start to cut in and out and shoot a flame out of the exhaust. if i sit and just rev it easy like 1/3 throttle at a time but revving it 1-2 sec apart it pops and backfires like a MOFO i got 2 vids ill post but they are from a cell phone idk if you can hear much of the cuttin out on it but i can

[mxpimp2000]

this vid is of steady throttle from 1/4-1/2 steady

http://s121.photobucket.com/albums/o224/mxpimp2000/?action=view&current=01-27-09_1456.flv


this vid is where u can hear the hesitation from 1/2 - WOT

http://s121.photobucket.com/albums/o224/mxpimp2000/?action=view&current=01-27-09_1501.flv

[ohsobad_chevy]

I can't really tell from the video because the sound quality. But what I can hear is definitely a jetting issue.

Are you absolutely sure that you have a 168 main and 48 pilot in the bike? Did you check for any air leaks intake and exhaust?

[mxpimp2000]

iam 110% i pulled the jets myself since i wasnt the one who jetted the bike. i pulled the carb off and made sure everything was sealed up perfect there is no leaking boots or exhaust

[ohsobad_chevy]

Originally posted by mxpimp2000
iam 110% i pulled the jets myself since i wasnt the one who jetted the bike. i pulled the carb off and made sure everything was sealed up perfect there is no leaking boots or exhaust

If you have checked everything else, then it has to be a jetting issue.

I think that you are too rich on the pilot and too lean on the main......go to a 45 pilot, NCVQ needle on the 4th position from top, 172 main and 2.5 turns out on the screw.

[mxpimp2000]

what do u mean to fat on the main?lol a guy on central said he thinks im to rich on the pilot also, i was thinkin it had to be gettin to much gas and causeing the backfire and it smells like gas really bad when u try to start it when its cold if u pump the gas any or use the choke but after its warm u can hit the button once and it fires up

[ohsobad_chevy]

ooops.......typo, my bad. I fixed it.

From what I can hear and what you are telling me, you are too rich on the pilot for sure. Put a 45 in her and I'll bet she will clear right up. Also, when you get those mains from R1R, put the 172 in it and you will be very close.

[mxpimp2000]

i will try it when i get the jets and see what happens but ill have to find a 45 pilot

[Ride1Rob]

Originally posted by mxpimp2000
as of today im thinkin its gettin too much gas because when i got to start it it takes a while and if i push the gas any it just backfires and esp if i turn the choke on. idle it runs fine but the further i push the gas in nuetral it will just start to cut in and out and shoot a flame out of the exhaust. if i sit and just rev it easy like 1/3 throttle at a time but revving it 1-2 sec apart it pops and backfires like a MOFO i got 2 vids ill post but they are from a cell phone idk if you can hear much of the cuttin out on it but i can

Man, you're killing me! When I asked you a few days ago if the bike starts right up you told me YES! When I asked if it had hesitation or bogging you told me no. It's really hard to help someone via internet when the problem is not diagnosed properly.

[mxpimp2000]

Originally posted by Ride1Rob
Man, you're killing me! When I asked you a few days ago if the bike starts right up you told me YES! When I asked if it had hesitation or bogging you told me no. It's really hard to help someone via internet when the problem is not diagnosed properly.

i dont remember sayin there was no bogg or hesitation lol thats what the thread is about but today i went back to the shop and thought to start it and it being 34 degrees idk if thats the cause of starting issues but if i use the gas or choke to start it backfires and smells like gas bad

[Ride1Rob]

Another thing, your main is not causing the bike to run like crap. When you hit the throttle to WOT the bike is not cutting out or backfiring. You pilot is surely too big and your needle is the cause for the rest. You could go up or down to make it perfect. Changing a main up two sizes could rob you a couple hp. I've tested it and know first hand. Ex. my bike with all the mods on it would run my cousin on his LTR450. With a 170 I could take off and play with him off the line. This was also true in acceleration. Took the 170 out and put in a 180 and he'd leave my arse of the line. I'd estimate the difference was at least 4 maybe 5hp. That's why you see most posts of guys with mods like mine or more getting dusted by bikes with pipe and filters. If it's not jetted correctly it's not going to perform at it's best. You have to use a dyno or use the but dyno :D .

[mxpimp2000]

Originally posted by Ride1Rob
Another thing, your main is not causing the bike to run like crap. When you hit the throttle to WOT the bike is not cutting out or backfiring. You pilot is surely too big and your needle is the cause for the rest. You could go up or down to make it perfect. Changing a main up two sizes could rob you a couple hp. I've tested it and know first hand. Ex. my bike with all the mods on it would run my cousin on his LTR450. With a 170 I could take off and play with him off the line. This was also true in acceleration. Took the 170 out and put in a 180 and he'd leave my *** of the line. I'd estimate the difference was at least 3hp easy.

so the main isnt causing the hesitation from 1/2 to WOT when i stab it and it take the bike a sec to catch up b4 it hits wide open point

[Ride1Rob]

Like I told you a couple days ago. Your main jet is from around 1/2 to full throttle. Your needle from around 1/4 to alil over 1/2, and your pilot from idle to around 1/4. They overlap from bottom to top. From the sound bite that I heard the bike is okay at WOT. Maybe you didn't rev it long enough.

[mxpimp2000]

its FIXED now i put the 172 in it and did the ap zip tie mod and it screams like no other didnt change the needle or pilot jet

[ohsobad_chevy]

Originally posted by ohsobad_chevy
If you have checked everything else, then it has to be a jetting issue.

I think that you are too rich on the pilot and too lean on the main......go to a 45 pilot, NCVQ needle on the 4th position from top, 172 main and 2.5 turns out on the screw.


Dammmnn I'm good. :p

Good to hear you got her runnin' better.

[Ride1Rob]

Awsome, I was surely wrong on it lol. Would have never thought that 172 would have made that much difference without the needle. Glad ur back up and running.

[mxpimp2000]

Originally posted by Ride1Rob
Awsome, I was surely wrong on it lol. Would have never thought that 172 would have made that much difference without the needle. Glad ur back up and running.

but thanks 2u its good to go and its not 110% when its real cold outside but 40 degrees or warmer its about perfect..my buddy was swearing that if i did the ap zip tie mod that would fix it so we did that and swapped tha main jet out so idk if the main helped the most of the zip tie mod did either way its running good

[hawood]

Just wondering, what is the ap zip tie mod?