My '84 Yamaha Virago xv700 runs on prime, skips and misses on "on".?

S

Snowdog

New member
It seems my Virago has had an issue where it will intermittently run on one cyclinder. I've replaced the petcock (new oldstock OEM), replaced many of the fuel and vacuum lines and just recently pulled and rebuilded the carburetors.
It will start up fine now (thanks to last year's starter-grind fix), but it will still, on occasion, run on one cyclinder. This will sometimes work itself out, but I suspect it does this less when on the prime position. However, I'm not entirely convinced it's a fuel issue.

Has anyone ever had a bike that would sometimes run on only one cylinder that was fixed by replacing the ignition wires, coils, etc.

Thank in advance!
 
I agree with the cap't on this one. Block that extra line off and you will probably straighten the problem out.

If it doesn't, then the problem could indeed be with the coils or plug wires. Most people never think to replace motorcycle spark plug wires, but they too wear out from use, uv rays hitting them and heat. Test the coils as per your repair manual. Aftermarket coils are fine to use from the local autoparts store and a whole lot cheaper than the ones from Yamaha, its just making them fit sometimes is a pain.
 
yup that mixture control valve is junk,its on the left side of the bike.One of the first things I got rid of when I chopped my 81 [first year] virago.
 
1985 Yamaha Virago 700 here.

It runs on one cylinder (the forward cylinder) when the oil level in the engine is too high. Put it up on the center stand, and look at the little window on the left side of the engine. The oil level needs to be between the two lines.

If you've been running on one cylinder, you need to clean and gap your spark plugs too. Not running can foul a plug. Quick and easy to do, takes me less than 20 minutes.
 
the old viragos have a black plastic "mixture control valve" that acts as a big vacuum leak & causes one cylinder to misfire at low rpm when its not working right.
one of you're manifolds ( I think its the front one) will have an extra vacuum line going to this valve.
just block this extra hose nipple at the manifold & see if it helps.
the bike will run better without this mixture control valve hooked up. its just some kind of anti pollution crap any way.
 
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