Throttle sticks in hot weather

[Ken Block]

The throttle on my 1969 R60US sticks open in hot weather. Any suggestions on where to start looking to solve the problem?

[Lonnie]

Is this the throttle control,(twist grip),or the slides? If the slides,I have had this happen and cured it by ever so slightly honing the slide so it wouldn't stick when it got hot. You must be carefull here so you don't make it too loose,that will create other problems.

[Dave Thomas]

The carb body could be slightly warped, probably due to over-tightening at some time. When it gets hot it probably changes just enough to make the slide stick. If you disassemble it you should see bright spots where it's been sticking. You can lightly sand these places (use 600 wet-or-dry) until the fit is better. Or replace the carb body.

[Ken Block]

Dave: Thanks for the info. I'm going to work on my bike this weekend to try and find the problem. Regards, Ken Block

[Ken Block]

Lonnie: I've have never done any mechanical work more complicated than changing a tire, so please excuse my ignorance. I don't know what a slide is. The throttle grip returns but the motor continues to accelerate. I was going to take a shot at fixing the problem this weekend. Any additional suggestions? Regards, Ken Block

[Dave Thomas]

The slide is the cylindrical part that moves up and down inside the carburetor when you turn the throttle grip. It has a thin pointed needle inserted into the bottom that moves with it. If you unscrew the large ring off the top of the carb, you can pull the slide (with other assembled parts) straight up and out. You will find the end of the throttle cable is captured in a notch in the slide, and a large spring between the slide and the cap. Be very careful when handling this assemble so as not to damage the needle. You shouldn't need to disassemble things any further if you're just polishing the slide. Good luck with it!

Dave

[Ken Block]

Dave: Thanks for the info. I disassembled and cleaned the throttle yesterday. I then rode the bike for an hour in 85 degree weather and the problem did not occure. If it does, I'll try your suggestion. Regards, Ken Block

[Lonnie]

Ken sorry I didn't respond to your inquiry,I was away from this board for a few days. Anyway it seems like Dave told you everything,yes sometimes just cleaning the components is enough.

Lonnie

[Ken Block]

Lonnie: So far so good with my repair. Regards, Ken Block