250 f jetting problems

[sfiegen]

I recently purchased a 2010 250f and need some help with the jetting. When you twist the throttle hard you may just as well hit the kill switch because it will imediately die. I have a friend that rides a wr450 and he had a similar problem. he installed a pump cover and it helped a bit but did not take care of the problem. He said it was a jetting problem and he had a local yamaha mechanic fix his bike. any help with the problem would be greatly appreciated. thanks

 

[husley]

Yuck

Accelerator Pump? Both of my wife's 250's had the same issue when they were stock.

Fixed it with a JD Kit (or is GG using EFI on the yama motors?)

 

[GMP]

No EFI. I'd hit the jetting and Yamaha 250F forums on Thumpertalk. You should find more than enough jetting info to get started. The JD kit will be a shortcut, I know from riding one it works very well on an '07 Yamaha WR250.

 

[GasTimppa]

Jetting should be near about 85 / 182. Mixture screw 2 turns out. Here it works fine (Finland = about sealevel) Att least Yammies and my friends 250f does...

 

[Jakobi]

Have an 04 WR250F myself. Suffers the horrible lean hesitation when whacking the throttle. You could try the o-ring mod on the fuel pump with your current jetting. Cheap quick and easy.

Otherwise like everyones said, JDs kit for this bike has been well developed and is a quick and easy way to have the bike running well. They really work.

 

[Bearman]

ec250f 2010 jetting sea level Australia

42 or 45 pilot
OBELQ needle (from 01 yz250f) 3rd or 4th clip
165 main
no need to mod throttle pump or change anything else