Snowmobile Repair: aritic cat puma carb., air screw, carb settings

Question
I have been repairing a 1995 aritic cat puma that has been laid up for several years. I have cleaned the carb., the tank, and new plugs. There was a crack in the manifold that I repaired. There seems to be good spark. The machine runs, for awhile but seems to be rich. Them it stop. What are the carb settings, and am I missing something.

Answer
Hello Paul,

  There are a few things that could be causing this. First, the manifold could be leaking. Unless the crack was welded, it should be replaced. As for carb settings, there are 2 on the Mikuni VM carb. One is a large screw that points straight out, and has a visible spring on it. This is just the idle speed screw. On the other side, there is a small screw, that goes into the carb at an angle. This is the air screw shown here: http://www.brownsleisureworld.com/Parts/SNOWMOBILE/1995/1995COUGAR(95COA-1995)/CARBURETOR.htm  .  This should be about 1 turn out, from being turned all the way in. Another thing to consider would be the spark plugs, which are the #1 problem sleds develop. Try a fresh set of NGK BR8ES plugs. This should help. Hope this helps you. Let me know if you have any other questions. Good luck with the sled! --Arcticatman