Re: new carb time I think

Tue Feb 26, 2013 5:22 pm

granps55 wrote:Got my frame fixed, then went to work on the cub, just adjusting the governor really helped a bunch, still gonna work on the carb. There is no differance when I adjust the air/fuel mixture screw, will have to address that one.


Don't forget to open the two small holes in the throat of the carburetor with a thin copper wire. They are part of the idle circuit, and may help explain why no response to the air adjustment screw. Also, you are adjusting air, not gas, so open it up to lean it out, close it down to richen it up. Backwards from most small engines.

Re: new carb time I think

Wed Feb 27, 2013 11:33 am

I've never noticed that the idle mixture screw does much of anything, and I've had four different Cub carbs since I got into this.

Re: new carb time I think

Wed Feb 27, 2013 5:38 pm

You won't actually notice a lot of difference in the low speed idle. The best way to get it set right is to "blip" the cub throttle from idle to full speed very fast; if it stumbles at all on the way up, adjust in or out until it goes to full speed with no stumble or hesitation. Only on one cub or two have I actually seen black smoke as idle got took rich.

Re: new carb time I think

Wed Feb 27, 2013 5:45 pm

Thats good to know, I just adjusted it and it is smoother now

Re: new carb time I think

Wed Feb 27, 2013 5:55 pm

granps55 wrote:Thats good to know, I just adjusted it and it is smoother now

That's great! I think you'll be glad you didn't buy that new carb.

Re: new carb time I think

Wed Feb 27, 2013 6:26 pm

I think that is an idle adjustment, not air/fuel mix.

Re: new carb time I think

Wed Feb 27, 2013 6:40 pm

Actually it sets the response of throttle from low to high speed.

Re: new carb time I think

Wed Feb 27, 2013 8:58 pm

Thanks, Cecil.