1988 Yamaha Virago XV 750 - Missing on one cyl semi-warm

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gflanders · Sat Jul 01, 2006 10:14 am

Bought used in '95 and for all the years this engine has given me trouble by missing on one cylinder under low RPM and on acceleration. I have tried plug changes and draining fuel from carbs - no improvement. When engine becomes fully warm the problem goes away.
I have heard that this is a common problem with this bike. Can anyone help with a fix or other info?

xsyamahadg · Fri Jul 07, 2006 11:16 am

I can't say for sure this is your problem, but I know this from back when I was looking at the Viragos: Some of the older viragos had a problem with the rubber boots leading from the carb to the heads. Those boots have a habit of getting brittle from age and developing hair line cracks in the rubber which allow air to enter the intake, causing the bike to run lean when cold. The old brittle boots also make it hard to get a good seal where it hooks to the carb. I saw many which were patched with two part epoxy to seal cracks. XS

oldschoolorange · Sun Jul 16, 2006 4:57 pm

do a compression and vacume test on thet cylinder. that will give you an idea

scottsxv1k · Tue Jul 25, 2006 8:34 am

i just rebuilt the carbs on my 85 and i know if the float level is too low that cylinder will run lean even acting like its not running at all and will also show no difference when that plug wire is pulled while running. by taking a clear hose with an adapter that will fit in the bottom of the carbs, you can then check the float level.