Jetting problem

strungxout

strungxout

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Ok, so I had the bike running decent. From half throttle on it ran great, but below half throttle it bogged a little bit.. So I went up 1 on the pilot. Fired right up and ran great. I adjusted the mixture screw a little bit and took it out for a ride. Got back and let it idle while I did a final adjustment on the screw, and before I could touch them it died out. Tried the electric start and it wouldn't turn over (and its always fired right up with the e-start). Gave it a couple kicks and it fired up for a second, then died right out. I let the bike cool down for a couple hours and had the same problems so I left it alone for the night. Tried again this morning and it fired right up... But as soon as the motor started getting warm it cut back out and I had the same exact problems. I'm not overheating the bike, when I let it run at idle it was only for 30 seconds at a time, and I keep a big fan running on it. I didn't have this problem with the stock pilot jets, but there's no point in switching back to them because it wasn't running right with them in. Any ideas? Anybody have a similar problem? Thanks.
 
Whi you changed the pilots?.Set up the carb as the manual say and the bike should run right unless you have some other problem elsewhere.
 
No need to change the pilots most of the times.Try to increase the fuel with the mixtures screws.If the screws are 1 turn out the try 1/5 or 2.If that does not do it then raise or lower the carbs slides needles 1 notch.Test the bike after you make a change.The cut exhaust could be the problem or the pod filters.Adding aftermarket exhaust and filters can cause lots of problems on the carburation so unless you restore that unbalance created by adding those parts the bike won't run right.it takes take to play with the fuel mixture but you will sort it out.
 
Tz250racer said:
No need to change the pilots most of the times.Try to increase the fuel with the mixtures screws.If the screws are 1 turn out the try 1/5 or 2.If that does not do it then raise or lower the carbs slides needles 1 notch.Test the bike after you make a change.The cut exhaust could be the problem or the pod filters.Adding aftermarket exhaust and filters can cause lots of problems on the carburation so unless you restore that unbalance created by adding those parts the bike won't run right.it takes take to play with the fuel mixture but you will sort it out.
Click to expand...

Well the thing is I cut the exhaust and added the filters when I first started my build about 4 months ago. I've been screwing with the adjustment for a couple weeks now and finally got it to the best it was going to get... And the bike hesitated and jumped up to half throttle. I had no problems other than that. So when I first swapped the pilots the bike ran great, then just died out and all these problems started. I've been adjusting it all day and the bike just keeps dying out as soon as it warms up.
 
I think another problem of some sort, maybe electrical, has developed unrelated to the jet change. Changing a jet won't have an effect like that. It either works or doesn't work from the moment you put it in. Did you pull the tank and carbs to do your jet change? Maybe you bumped and disturbed some wiring connections and they've come loose or unplugged.
 
5twins said:
I think another problem of some sort, maybe electrical, has developed unrelated to the jet change. Changing a jet won't have an effect like that. It either works or doesn't work from the moment you put it in. Did you pull the tank and carbs to do your jet change? Maybe you bumped and disturbed some wiring connections and they've come loose or unplugged.
Click to expand...

I just dropped the float bowls with the carbs on the bike. If it were electrical would it be happening all the time instead of only when it gets hot? Thanks.
 
Are you still using the stock coils? They weren't much when new and 30 years later hasn't helped.
Often when the coils start going bad they run fine at first but stop working as they warm up.
 

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