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Discussion Starter · #1 ·
:angry I bought a new YFZ for the wife to ride and it was cooking the
header pipe cherry red for the first 12 to 14 inches so bad I was worried
it might be too lean. I asked around and everybody had a different reply,
some said it was normal others said re-jet. I decided to try removing the
air box lid, removing the spark arrestor, adding the GYTR jet kit (Got ripped
on that by Mission!!!) and doing the exhaust cam mod. When I got done
I had a bike that wouldn't idle at all. I have put back every thing except the cam
mod & it still won't idle. The throttle has to be 1/4 open for it to run. I have
double checked the pilot jet & it's circuit to make sure it's not plugged. Is
there any quirk to these P.O.S. 4-stroke carbs that might be causing the
problem ? I've spent $7,500.00 on another Yamaha after I swore I never
would again and now it's sitting the garage un-rideable & I'm furious.
Any body who knows what they're talking about, that can help, would be
appreciated. Thanks..............

-Downside
 

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what piolet jet are you currently running? I had to go up to a 48. The piolet jet controls idle to 1/8 throttle along with the air mixture screw.
 

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For stock, put it back together.
Change the Pilot to 45 and the Main to 165, Mixture screw @ 2 1/2 turns out, stock needle on the 4th clip. (this is what I learn from everyone on this site). No more glow.

With the Lid OFF, you are adding more air to an already lean bike. (Makes it worse, leave it on.)

You can take the Sparky out and it should make it a lit better along with the jetting, mine is still in.

Check out "Daddog's Jetting page", or :search this site, if you have any type of pipe on it. They are very helpful.

I let it warm up and then adjust the idle to where it feels/sounds right.

Cheers.
 

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take it back to the dealer looking like this ---> :angry
i think they'll comply :D
 

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yeah.... sounds like with most of us when we brought home our new YFZ's home, glowing header (possible lean condition) Some rejetted the pilot, others let the break in process complete before tearing it apart to jet/mod it. Either way sorry to say its not the POS YFZ its the tuner. It could be anything cam placed in wrong, obstuction of fuel in a venturi, miss adjustment of jetting.
You preformed everything at once so you could have gonna wrong in any of your steps. Your best bet is to put it all back to the way it was giving to you and have the dealer take care of your needs since it seems you have lost your patience with it. It could be any part of your process. You have 6 months of complaining to them make use of it. 8)
BUT, I wouldnt be surprized if they didnt cover it under any warrentee because you tinkered with it. Unless you are in good with the dealer.

So again put it all back to OEM with a 45 pilot making sure to have clip on needle the 5th clip to get it on a decent baseline again and go from there.


Oh and the FCR carb is the best carb on the market. :nono



:yfz
 

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Yooo dude, this happend to me! My YFZ when i first got it, barely ran at an idel and when you were riding it and u pulled in the clutch, it would want to just shut down. So i took apart the carb and found out that the IDEL screw or what not was set too high when factory put my bike together. After i fixed it, the thing runs like GREAT! But trust me, i was furious with that whole idel w00ter too. :angry Just try that out, that might be the problem.

Blue YFZ
Sparks full exuast
Jet Kit
KandN filter + outerwear
Pro Flow Kit
PRM Skids
Renthal Fat bars
Acerbis hand guards
Oury Self cleaning waffle grips :lol
Pro design kill switch
Gibson Pro peg nerfs
GYTR Number backrounds
GYTR Bumper
 

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Downside you have done everything but adjusted the idle screw. Sounds like that may be your problem. Have you adjusted your idle screw and made it idle higher?
 
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