Motorcycle Repair: carburetor problem, air leaks, incorrect fuel

Question
I recently bought a 85 kawasaki KLT110A2 3 wheeler. It has a Keihin/PC18 carb. Problem is it wont idle or rev up with the choke off. I have cleaned and cleaned. Turn the choke on and it will rev right up. Turn choke off and it just boggs down. Checked jet sizes per the repair manual, all are right. My main question is what goes between the carb and the carb holder? Mine has an o-ring, but in the manual it says calls it a gasket. There is a port coming out right in the groove where the o-ring is now sitting. Could this be my problem? I have looked all over trying to find a parts break down but every one i have found doesn't list this gasket or o-ring, whichever it is.


Answer
Bill,

there is an o-ring on each side of the
insulator block between the carb and the engine.
Any air leaks will lean out your fuel mixture.

Have you checked the flow of fuel from the
gas tank valve and checked the needle jet
above the main jet in the carb body?
Also push a small wire through the idle and main jets
to make sure they are clear.

A sticky float/float valve needle or incorrect fuel
height in the carb will hinder the fuel level.

Is the compression okay? Above 100 psi at least?
Valve clearance may need checking.

You may have an air leak on the carb insulator
if it looks odd. The o-rings should seal it
completely. Maybe something is wrong with the insulator?