1991 rm250

[Perry427]

Just bought this bike, installed new choke assy, air cleaner and general clean up. cranks and runs fine but but will not idle.
I don't know which screw does what?, there is a large adjustment screw on the left side of the carburetor and a small
one right below it, which does what and how many turns on each.

Thanks in advance

 

[Perry427]

Com'on fella's, can anybody tell me which adjusting screw does what on my 1991 RM250 with a mukuni carburetor,
there are two, a large one on and a small one.
If there is a detailed diagram on the net please tell me where it's located.
Any help appreciated.

 

[JG614]

Perry427,

It's been a while since i had mine but, look for the screw with a lock nut that should be the idle adjustment, the other is the fuel/air screw which base setting should be about 2 1/2 turns from seated (turn it in all the way until lightly seated then turn out 2 1/2 turns) My Husky has a mikuni carb on it and the idle screw on it is in the center if you are looking at the carb from the side, kinda where the slide would be. I know I would kinda like a thumb screw on mine because it's a pain to adjust as it idles to fast when cold or to low when warm. oh well I hope this helps.

Later
Jeffro

 

[Perry427]

The screw in the middle, on the side is large, looks like it's for your thumb and a phillips screw in the middle, either /or............ I'll give it a try ..........Thanks

 

[a454elk]

The one closest to the intake port from the air box is the air screw, should be a flat head, flush with the carb case. The other is the idle, make sure the curcuits are all cleaned out though, you may be trying to compensate for a clogged jet or path. Good luck!

 

[Perry427]

Finally!!!, thanks a454elk, I have something to work with now.....if I take out both screws, clean and reinstall, how many turns out to start with?.

Perry

 

[Matt Fisher]

Air screw is listed at 1 1/2 turns out.

The Mikuni TMX's idle screw goes right through the carb body, and touches the bottom of the carb slide. Turning it in raises the slide, bringing up the idle.

 

[a454elk]

Depends on how you want it to idle. Stock is set to idle for about 10 seconds after backing off the throttle then it dies. If you want it to stay idling, get it warm and turn the screw in until it stays running just slightly. Good luck!