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Discussion Starter · #1 ·
Hi there, I have been working on this quad for about a month now. I rebuilt the quad up from a 1998 300ex atv. The old 300ex engine case cracked so I removed the engine, and put in a 1991 Honda 250x bored out in its place. Also I had to put a 300ex Top end because 1 of the rocker arm nuts came loose and actually fell off when I got it running the first time. So I put lock tight on the bolts to prevent that from happening again.

2nd time, I put it all back together got the engine dialed in and timed, got it started and it ran ok. But it was running real rich, when you hit the gas about 3/4 throttle it bogged out and it sounds like the 300ex carb isn't jetted right. A puff of black smoke came out of the exhaust and then it died. Tryed to start it back up and nothing happend. I Checked out the spark plug and it is black.

Now what do I do next? Getting very frustrated.
 

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if it's bored it should run close to stock jets.What exhaust do you have on it.Also your using a 250x wiring harness right.The 300ex cdi and stuff won't work for the 250x.
 

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Discussion Starter · #3 ·
Yes, I replaced the 300ex wiring harness as well as the cdi back to the 250x. I have a FMF Pipe and silencer on it.
 

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Ok you need to run a 42 pilot and a 130-135 main.Remove the airbox lid and get a good K&N or foam type filter.
 

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Yep no problem.If you have anymore problems just tell me.
 
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