HIGH RPM s ON CRUSE

[Do Lee]

On Tues. evening this week I took a little journey (350 miles) along the Texas coast line down to Corpus Christi. Bike ran fine on the trip down. Stopped at Texas Roadhouse in Corpus for dinner, then feed the bike and proceeded on the journey home. When I was coming to the next town (about 50 miles down the road) the bike would not idle down. It was running around 5000 RPM, I had to lug the motor down to get through town at the proper speed limit. When I got home did a quick glance about the bike.

* Throttle assembly & cable free not binding
* Carb butterflies seemed to be opening and closing freely, I had just recoated carb intake manifolds with Yamahabold #5 back in March and have put around 2000 miles on since.
* Vacuum advance line looked ok.

I was planning on pulling carbs to change out the top and bowl screws with allen head bolts, and to make sure there is no binding on the butterflies. I am also planning on checking the mechanical governor to see if I lost one of the springs.
With all the end of school activities going on now I have not had time to throughly check out the bike which is 79XSSF with a standard tank, no octopus.

What else could cause this to happen?

Thanks,
Do'Lee

[John]

Did you check the cable at the metal elbow near the handle bar, where it goes into the right side switch housing? When I replaced the starter button on Foster Child, I overlooked getting the cable into the metal elbow, and it would not idle down. I don't how yours may have gotten unseated from the elbow, but that is something to look at.

[tab1324]

carb diaphragm or sticky slides?

Maybe you have a bad carb diaphragm or sticking slide? You should be able to check if you can get the airbox off. Just open the butterflys (by hand with bike off) and take a look. Maybe slide the slides up and down to make sure they're free.

I would think it's more of a slide issue than a diaphragm thing cause if the diaphragm leaked, the slides wouldn't go up.

I suppose it's possible that you're all of the sudden running really lean because a lean mixture will cause the rpms to stay up. Maybe something came off of your redone intake boots and is sticking in the opening?

My $0.02

Tom B.

[Do Lee]

My high RPM problem is fix...
After my last carb cleaning (I do a complete teardown and submerge the carbs in an agitating parts cleaner) one of the butterfly screws had come loose allowing that butterfly to shift and bind up against the carb body not allowing the it to close down for proper idling. Re adjusted all butterflies and locktited screws to hopefully prevent this from happening again.

[skids]

I guess the screw was "digested" by the engine and passed through the valves?!

Originally posted by Do Lee
My high RPM problem is fix...
After my last carb cleaning (I do a complete teardown and submerge the carbs in an agitating parts cleaner) one of the butterfly screws had come loose allowing that butterfly to shift and bind up against the carb body not allowing the it to close down for proper idling. Re adjusted all butterflies and locktited screws to hopefully prevent this from happening again.