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1998 YZ250 tuning problems

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Looking for some help with a bike I just rebuilt. The bike came with a rebuilt bottom end. The cylinder was in good shape. I measured and ordered the correct piston and installed a weisco piston. Rings are installed correctly. Compression is good, but bike is very difficult to start. The only way I can start it is to kick it over wide open. The bike won't idle. I can turn the air screw while barely reving the throttle and get no response from turning the air screw. I have pulled the carb and cleaned jets and every bit of the carb several times. Brand new boyesen reeds are installed. Got spark       I could use any help. Fuel lines are good. I never saw the bike running and I've installed Fmf exhaust and silencer because the bike didn't come installed with exhaust. I've bought a jet kit which I feel is like my last straw before having to take it in. Any suggestions would be greatly appreciated 

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8 minutes ago, Kevinyz said:

Looking for some help with a bike I just rebuilt. The bike came with a rebuilt bottom end. The cylinder was in good shape. I measured and ordered the correct piston and installed a weisco piston. Rings are installed correctly. Compression is good, but bike is very difficult to start. The only way I can start it is to kick it over wide open. The bike won't idle. I can turn the air screw while barely reving the throttle and get no response from turning the air screw. I have pulled the carb and cleaned jets and every bit of the carb several times. Brand new boyesen reeds are installed. Got spark       I could use any help. Fuel lines are good. I never saw the bike running and I've installed Fmf exhaust and silencer because the bike didn't come installed with exhaust. I've bought a jet kit which I feel is like my last straw before having to take it in. Any suggestions would be greatly appreciated 

Pull the carb apart.  The pilot jet and possibly some more fuel passages are clogged up.  Excuse me, replace the pilot jet it is still plugged up even after your cleaning attempts.

Edited by GlennRay

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Thanks man. I ordered a new jet kit so I'll install the new jets and clean all the passages again and see if that does the trick. I ordered a 6 sigma jet kit which I gave them all the specs about the bike. Location above sea level, model of carb, model and year of bike, and exhaust specs. Hopefully it will work 

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What jets come with the kit ?

did you try to wind the IDLE screw in or just the airscrew ?

 

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The choke knob can be turned for idle adjustment which I tried. Otherwise, there is just the air screw 

IMG_2196.PNG

Edited by Kevinyz
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14 hours ago, Kevinyz said:

Thanks man. I ordered a new jet kit so I'll install the new jets and clean all the passages again and see if that does the trick. I ordered a 6 sigma jet kit which I gave them all the specs about the bike. Location above sea level, model of carb, model and year of bike, and exhaust specs. Hopefully it will work 

Can you update when you install the kit? Interested to see how it works for you. 

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