Motorcycle Repair: Rough idle, fuel system treatment, motorcycle repair

Question
I have a 1991 Yamaha Virago 1100cc with 10K miles.
I take weekend trips maybe 4 times per year. I also ride it a couple of hours every other month. It have never had a tune-up or other work on the motor. I'm having a problem with "rough idle". I think that laquer has "built up" in the carb because of infrequent riding. I'm not experienced in motorcycle  repair. What do you recommend. Also is there a gas turn off valve on this motorcycle. If not, can one be installed and does that make sense. I thinking it would be a good idea not for the gas to set in the carb for extended periods
Thanks in advance for your response.
Kirt

Answer
Hi Kirt.

You definitely have varnish in the fuel system since you don't ride it often enough to keep the fuel system clean.

 Start by trying a fuel system treatment.  Something like the STP with jet fuel is what I recommend.  If the build up isn't too bad, then a good ride with a bottle of that in the tank should clear it up.

 If that doesn't work, then you will need to replace the fuel line, clean the carbs and, to prevent additional contamination after you have cleaned the carbs, re-seal the tank.

The fuel selector valve is more than enough to stop fuel flow when the bike is turned off.  Fuel flow is activated by a vacuum operated valve in the selector valve, so installing a shut-off valve is just a waste of time, money and effort.

You are right about it not being good for fuel to sit, long term, in the bike.  If the bike is going to sit for extended periods between rides, then I suggest draining the entire fuel system of any remaining fuel just after each ride.

 Do not store the fuel for the next ride.  Use it up somewhere else or you will end up putting varnished fuel back into your fuel system.

 Just get a gallon or so to put in when you are going to go for a ride and repeat the proceedure between rides.

Good luck and ride safe.
FALCON