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1987 XR80 running badly after top end rebuild and new carb.

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So I just rebuilt my 1987 XR80, new gaskets, piston, cylinder head, valves, everything. I also put a new carb on it. It started right away once all was said and done, but then it died again. I started it again and kept giving it throttle to keep it running and it'll run for a minute, maybe minute and a half and then it dies. If I don't give it gas it'll die right away. Anyone know what my problem could be?

Edited by Jim Beam

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Well I had already tried adjusting the idle and air screws but I hadn't thought of keeping both of them snugged up. The bike doesn't idle very well but it's not high RPMs like you would think with the idle screw all the way in. It's ridable now though, thanks for all the help!

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On the new carb, do you have the same size jets and the needle in the same position? Valves done correctly? Cam chain in right spot? Check for air leaks?

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No air leaks, timing is perfect from what I can tell, valves are 0.05mm, not sure about the needle position or jet size. I grabbed a generic carb off ebay that said it fits an '87 XR80, I guess I should have gone with the OEM carb.

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I'd probably do that on a Chinese pit bike, but not a Honda. At least if you got a Honda oem carb, you can get the proper rebuild kit or parts, or be sure that you're able to get the correct jets. I've read on here that the cheap chinese carbs, the jets don't exactly match up. Hope you're able to get it going with what you got. You didn't use an old spark plug did ya? 

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