a friend has an LT300,and another guy has an lt185, and these quads both idle inconsistently.

They have to keep adjusting the idle speed screw, the idle won't stay right.

It seems as though the pilot screw has to be turned out pretty far. I put a pilot jet 2 sizes richer in one of them, and it helped. Maybe I gotta go even more.

Does this problem ring a bell? Is there a seal that could be leaking. It seems like this happens to lots of old motorcycles.

 

Is that the carb that has the primer pump on the side of it ? If it is the diaphram is got a hole in it and is leaking air and causing the erratic idle I fixed a LT125 that did that the part was 32 dollars and it idled fine after that.

 

I am by no means an "expert", but the first thing to do is dis-assemble the carb and clean it....especially take a close look at the idle circuit. Lots of gunk can build up in carbs over the years.