The o ring is rotted in my carb. It is a Keihin carb. It has been cleaned and everything looks good. I got a good idle, but it seems to fluctuate sometimes, and I believe it is because the o ring is missing on the needle.

I do not need to buy a kit, but would like to go to the hardware store and get an o ring that fits.
The o ring kit from Harbor Freight did not have one small enough.

You help would be much appreciated. Thank you.

 

do you mean the tiny one on the air screw that is vertical and goes into the carb from below? I just put some antisieze compound on the threads. The threads are soooo fine that I can't imagine they would leak air to any noticable degree, plus a few of mine run great without it if that helps Idle flux? warm, cold? smoke? smells like fuel? Spray around the intake with carb cleaner and see if you can detect an intake vac leak. I'd be tempted to check the timing and maybe valve clearances if it's bothersome. We should do that every year or so anyway.