mikuni bs34 carbs

650mark · Posted: July 21, 2009, 9:01 pm Post subject: mikuni bs34 carbs

hi all, mark in mesa here. i've restored 4 xs650's and am now re-doing a '77 xs400 that has stock Mikuni BS34 carbs. same carbs used on older xs650's. the carbs are clean, all stock jets, air filters and exhaust, floats set correctly,no holes in the diaphragms, and the bike starts and idles fine. but when i throttle up to about 2500-3000 rpms the idle jumps up to 4000 and stays there. what am i missing here? can't find any vaccuum leaks, ignition works correctly, throttle snaps close when released... any suggestions would be great.
thanks in advance

renloy · Posted: July 21, 2009, 10:09 pm Post subject: Re: mikuni bs34 carbs

I had a similar issue and turned out my carbs were out of sync

650mark · Posted: July 22, 2009, 9:02 pm Post subject: Re: mikuni bs34 carbs

thanks for the reply. i just bought a morgan carbtune and sync'd the carbs. they were already very close, getting them spot-on didn't make any difference.

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