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Discussion Starter #1
We recently rebuilt my sons 1987 Moto4 225, new rings, valve job, New CDI and rebuilt the carb.

it will idle and it will run with the throttle open, but the transition is hell. Light throttle causes it to bog down and knock. Once the RPMs pick up it’s fine until it goes back to idle.

I ordered one of the aftermarket carbs. And the behavior is exactly the same. Valve lash is good, Compression is a little high per the manual (150) but that’s probably just the oversized piston

have tried adjusting both the needle and the pilot and nothing seems to make any difference

Any thoughts would be appreciated, I have a video of it running as well if the explanation doesn’t make sense.
 

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So, it turns out the issue was the New CDI box we put in. Seemed logical to replace it at the time since we had the whole thing apart and the old one is over 30 years old. Put the original back, reset the original carb to full factory and it runs great.

Those aftermarket parts they sell everywhere really are junk. We had also purchased a replacement carb when it wouldn't run right, but it wouldn't run all with the new one do we put the original back.
 
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