Revving to the moon….HELP

[JBryan91]

1995 Vmax

I spent all day fooling with clutch pressure plate, friction and Steelies. now works perfectly thanks to advise from other members on another thread I started. Now here’s the fun part. I spent the rest of the day replacing all rubber to chase a lean pop issue for a possible air leak. Carbs were professionally rebuilt. All rubber boots for airbox, carb to intake, and v boost were replaced along with intake o rings. When starting the bike with a little choke it pops loudly. I killed the bike and started it again and then suddenly the bike revved to the moon and I had to kill it with the kill switch. I then pulled the airbox and checked that all choke slides were closed along with the butterfly in the carbs. I am not sure what else to do and it’s very frustrating. The bike has k&n airfilter, jet kit, and cobra exhaust that was done by previous owner.

Could the vboost system cause unmetered air/fuel into the engine without throttle input? At this point I want to take a match to the bike. Any help is appreciated.

 

[99YAMAHAVMAX]

Needs synced.

 

[JBryan91]

After I cooled off from this lovely Texas heat, I walked back out to garage and looked again. All the butterfly’s are barely open…..Manually pressed them full close and started the bike. Ran well and didn’t “pop”. Will be adjusting in the A.M.

 

[Fire-medic]

Yes, a carb synch is always recommended after a carburetor removal/replacement.

Also, be sure that your carburetor cables are routed properly! I remove my cables at the junction block, and it's much quicker than going to the trouble of removing the cables at the cams in the carb rack. Another thing to check is the proper amount of free-play at the throttle grip. A lack of adequate free-play will cause just the problem you had. Binding cables can also cause that.


And for the cables:

 

[JBryan91]

Thanks Fire-Medic! This helped tremendously. After doing some digging I found that I put the RR boot clamp on backwards and it was causing the butterfly valve mechanism to catch on the clamp when attempting to return to closed position. She’s all back together now. I’m waiting on some vac gauges for the carbs then I’ll set a/f.

 

[Fire-medic]

OK, good you did the failure analysis, and identified the issue, and corrected it. Most important, besides you fixing the issue, is that you came back to the forum, and you informed us about the resolution. Your fix is now there for anyone else who has a similar issue and who takes the time to read the possible fixes by using the 'search' function, or the 'advanced search.' Thank you for that.