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72 CL175 runs rich

I doubt seriously that cam chain adjustment is affecting richness that much. With the idle at 2000 rpm, the mixture screws won't have much effect. Did you check the advancer to be sure it's retarding fully? Loose advancer springs will allow the engine to stay advanced more than it should at low rpm, making the idle hang.
 
Finally got it back together. New rings installed correctly this time. I'm not pumping oil out the tail pipe but its running very rich. The carb clips are in the top notch. Idle mixture screws are almost all the way out. I can get a decent idle at 2k. Anything below it will die. Only the right carb seems to have any affect on the rpm. Not sure where to go from here. Jets are stock, 38's and 90's.
The correct setting for the mixture screws is 7/8 of a turn out from GENTLY bottomed, adjusted 1/4 turn plus or minus to find highest idle and should remain there......
The ultimate setting should fall within that range (5/8 to 1 & 1/8).....SLIGHT deviation to compensate for modern fuel allows range of 1/4 to 1 & 1/4......
Idle speed should then be reduced from highest to 1250 to 1350 RPM....
IF adjusting the mixture screw has no effect, passages within the slow jet or carbs are blocked, or throttle-stop screws are set above idle range .....

Another possible is it is running on only one cylinder.......
 
Disassembled spark advance and relubed. Rechecked valves, reset points to .014. Reset timing. Adjusted carb air mixture screws to 7/8 turn open. Set idle screws to 1.5 turns. Verfied spark on both sides. Fired it up and viola...idles nice at 1100. It ran like that for about 3 minutes then started to struggle. It would only run at 2k, release throttle and it died. I had the sooty black fuel drips from the LHS exhaust manifold bracket. Still running rich. Not sure what to try next. The only thing I noticed is the alignment pin on the end of the camshaft is about 1-2 degrees off of the 12 o'clock position.
 
I finally got it dialed in. I ordered 2 carburetors from Amazon for $70. Purrs like a kitten. Obviously there must be a blockage in the idle passages.
Nice inexpensive solution, and proof that even small issues with these old carbs can cause rideability problems no matter how hard you work to get them clean sometimes.
 
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