Motorcycle Repair: 1986 virago s, sheet metal screw, brass screw

Question
My virago back fires when I let off the gas and when first hit the gas it olny has 10,000 miles on it.

Answer
If memory serves me right the "S" model was a 1100. They are possibly Hitatchi carbs which Yamaha has dropped for getting any parts. Check the pilot fuel screws to see it they can be backed out and richen lower end of the rpm range. The screws are on the bottom side and if they have not been messed with there will be plugs pressed in over the top of the screws so the owners cant mess with them. If they are there drill an 1/8 hole and be carefull not to hit the head of the brass screw. Force a sheet metal screw into the hole and take two screwdrivers one on each side and pry the plug out exposing the screw and leave out. The mix screw may need to be backed out to about 3 turns from all the way in. This will have to be done with the carbs out on a bench. Once the idle is set try adjusting this mix screw with the engine at operating temp to smooth it out. You may have to have the carbs syncronized to get an even draft flow on each cylinder. The brace in between the carbs has a slot that allows a roller to run up and down so the linkage moves equally.Sometimes the roller wears out ond doesnt allow for a smooth movement.