High idle when warm

[ZeroShadez]

So im sure you've all heard this a million times. But i couldn't find anything on here that answers my questions specifically.
So i have a 1978 xs650 special BS38 carbs.
Idles great at first until warmed up then the idle spikes to 3k. when it does this i can unscrew thr idle screw and bring it back down to normal. But normal for it being warm is unstartable cold. Also my choke lever is super floppy Alot of free play.
Could that be a factor in high idle

 

[ZeroShadez]

Anything guys?? I sprayed starting fluid around no change really. But when starting today the carbs blew off lol are they too loose is that the leak?

 

[5twins]

That's somewhat normal. If you set the idle speed on a cold motor so it will idle, it will run too fast once warmed up. You need to set the idle speed when the motor is hot. Set it to no more than 1200 RPMs. When cold, you just have to take what you get. The idle speed will be very low, maybe around 900 RPMs or so, and it may require you to give it occasional small throttle blips to keep it going. The idle speed will begin rising as the motor warms.

The choke lever has a couple special mounting parts to insure it's not too loose but rotates freely (#55 and 56 below) .....

#55 is a special stepped spacer. The smaller inner step fits into the lever hole. #56 is a spring washer to apply tension to the set-up.

 

[grizld1]

Carbs blowing out of boots is a symptom of mistimed ignition, often caused by worn weights in the advance governor. Start your troubleshooting by lubricating the advance rod, servicing and strobe timing the points, and correcting the advance curve if needed. There's plenty of information on ignition service here, and a few quick searches will give you plenty. If problems persist after you've serviced the ignition and set valve clearance and cam chain tension, come on back. All of those things should be done before you even think about carburetor work.

 

[joebgd]

Yes, set the idle when it's warm. When you start it use the choke as needed until it warms up.