I have a 2000z xvs 650 At around 50 to 55 mph it tryes to back fire or spudder i have to come off the throttle a little for it to stop. what could it be

SOURCE: XVS 1100 idle

at sea level there is 14.7 psi of air pressure, the higher you go the thinner the air. thus, need more air and less fuel. adjuster your idle air screw mixture.

SOURCE: 02 Yamaha xvs 650 dragstar classic that misfires when it warms up

First I would change all the spark plugs, and if that didn't make a difference then it sounds like the coil(s) are warming up and breaking down........when it starts to skip take a good pair of pliers with good rubber on them and pull each spark plug wire, when you get to the one that the running doesn't change then I would replace that particular coil

SOURCE: hi i have purchased a yamaha xvs 650 vstar classic

popping on decel is from a lean condition. More likely from a lean, or too small pilot jet.

David Belcher

• 1978 Answers
• Posted on Jan 24, 2011

SOURCE: hi i have purchased a yamaha xvs 650 vstar classic

If the mechanic did not replace the exhaust pipe gaskets in the head or on any connections between the head pipes and the mufflers , the air leaks could be igniting unburned fuel in the exhaust , causing the popping and back firing. Try replacing any gaskets in the exhaust system.
If you have a flat spot or hesitation when accelerating than you probably also need to rejet the carburetors. Bigger main jets should fix that condition. A jet kit may also contain differently tapered needles for the slides to help compensate for the change in the acceleration curve.