Motorcycle Repair: 87 vulcan cool running problems, vn 750, cold morning

Question
Mark for the past couple of years I have had a problem with vn 750 vulcan starting in when the engine is hot I mean summer hot stopping for gas then trying to restart.also cold morning starts and riding when I start it in the morning in around 4o degrees it will backfire big time maybe start mostly not.If it does while Im riding its bucking the whole 20 miles to work.At work I park in a heated bay when i leave it starts right up no problem. please help I love my bike but Im getting ready to trade if I can't figure it out I have brought to dealer they couldn't figure it out they allways kept it in their shop allnight.This all started when a dealer rebuilt the carb's because of a gas leak brought back to them they said they see no problem.ps the bike is very nice shape neaver been left outside without a cover on it or its been garaged thanks for your help!

Answer
Hi Paul,

I suspect the carburetors need additional work to restore performance.

The shop that cleaned the carbs may have done a thorough job, though the carbs are re-contaminated by the fuel that remained in the tank.

It's also possible that the shop damaged the carb's internal parts and/or didn't clean thoroughly enough, respectfully. Some dealerships hire unqualified techs.

I recomend having another shop check the carbs, or ship them to me.

Visit "www.vroctech.com" for more assistance.

Respectfully,
Mark Shively