Question about 1988 Honda CBR 400

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Engine missing threw full rev range and rpm fluctuating at idle

The engine missing al the time under any revs, leads and plugs fine. and at idle 3it jumps between 1000 and 3000 rpm

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  • Anonymous Mar 30, 2014

    sounds like missing at idle clears up at 2000 rpm


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Sounds like you definitely need to do a major tune up, that being you need to adjust the valves and cam chain. You most likely have very tight valves which will cause the erratic idle and misfiring. I'd also check to make sure you don't have any air leaks in the intake manifold. A cracked manifold will certainly cause a problem like this. One last thing would be to make sure the carbs are synchronized. If they are out of synch you will never get the bike to idle smoothly.
Let me know if these recommendations help or not. I'll advise after you post your findings.

Posted on Dec 08, 2008

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