Engine sometimes dies on cutting the throttle after high speed

[Lordofwyr]

Any help here would be appreciated.

Background - When I got her, she had set up in a garage for a long time, so I had to have the local Yamaha shop clean the tank of rust, clean the carbs and reset the RPM's to 1.100.

Since then, if I am running her a tad over the posted speed limits on the freeways (forgive me Texas State Troopers) and the engine is not heated to the set mark, which happens on cold days, if I suddenly clutch in and cut the throttle to exit the freeway, the engine occasionally drops below 1,100 RPM's and dies, which means I have to roll start her or hit the starter, which is getting annoying and dangerous in traffic.

It never did this pre-cleaning and tune up.

My brother suggested it may be a vacuum issue.

Any suggestions before I take her back to the shop?

:hmmm:
Thanks in advance.

 

[maleko89]

It sounds like the engine is starving for mixture at closed throttle. I would check the throttle cables and throttle butterflies. It could be that the throttle valves are closing all the way and starving the engine. Other than that, check your pilot mixture. How do the plugs look? Run it at idle for a minute or two and pull them. I'm assuming stock jetting?

Mark
#1098

 

[maleko89]

Check for dirty air filter too.

Mark
#1098