84 ATC 110 Carb tuning tricks

[bobotech]

Okay, I completely rebuilt my 84 ATC 110 carb today. Replaced everything with what was in the kit. Took apart the petcock and cleaned that out as the filter. Replaced the fuel lines. blew out all the passages with my air compressor.

I put it all back together and it wasn't running and fuel was pouring out of the bottom overflow hole.

Turns out that I didn't realize that the bottom screw on the fuel bowl isn't an adjustment but a drain screw.. If you want to drain the bowl, you just unscrew it and the fuel comes pouring out.

Replaced my spark plug and the bike now runs and drives and runs well. idles and all.

HOWEVER I am not sure what the 2 screws on the side should be adjusted to. The screw going to the throttle slide, I just screwed in all the way til seated and backed out 1 1/2 turns and the screw to the lower left of that throttle slide screw, I just seated and backed out 2 1/2 turns.

But i have no idea what either of those screws really do or what the proper adjustments are supposed to be.

Also there is a port on the top of the carb that is unknown to me. It is next to the throttle slide screw. What is that for?

Thanks!!!

[Xpress]

The two screws are the high and low air fuel mixture.

The one on the throttle slide should be the adjustment for making it idle higher or lower, so adjust it to a nice idle. The other one is a mystery to me lol. I think it is for the high range...

[bobotech]

Well I got the bike idling well but I'm still unsure of the port on the side of the carb. the one next to the throttle slide. I also am not sure what the best way to adjust the high and low fuel mixtures for starters.

[RIDE-RED 250r]

the screw on the slide housing is the idle speed screw. this controls idle speed only. and the screw below it on the carbs main body is the idle air screw. this screw regulates AIR at idle speed. So, by closing it, (turning it clockwise) you are reducing air at idle, thus richening your fuel/air mixture at idle speed. im unsure of exactly what the fact spec is for how many turns out on the idle airscrew, on most machines its between 1 and 2.5 turns out from lightly seated. if you have a steady, reliable idle once the engine is warmed up your adjustment should be ok. The open port you describe is most likely an overflow vent.

[MonroeMike]

From the manual.