mm U won't idle

jmducks1

Member
My mm U when I rev it up then go to idle it stays on high idle. If I move
carb Linkage by hand it will. It has a zenith carb and the factory Governor.
What is suppose to pull the carb lever down? What should I look for? Weights
all move on Governor shaft. What are the two flat head screws for on top of
governor?
 
It sounds like your linkage is binding. When you move them up by hand most of them are supposed to basically fall back down. You may have to bend the linkage slightly. They can be a little tricky. I cant remember if in one of the manuals also you can loosen the 4 governor bolts (engine NOT running) and move the governor slightly to find the proper spot where it doesn't bind. Where are you located?
 
The Linkage arm that goes to the Carburetor goes up and down freely when disconnected from carb. Is it suppose to move much up and down? What are the 2 flat tip screw driver plugs or screws for on top of governor?
 
The linkage is supposed to move freely when it is connected TO the carburetor, hence why it might be binding. Will have to look up about the plugs on the U. The R-Z governors used a stop screw on the side of the governor for adjusting high idle.
 
Zenith carb will change length of rod. Also if manifold has been changed the length of throat can be different causing governor issues. Governor rod must move from top of it's throw to bottom with out any binding. A worn governor can be felt by movement of shaft. Very seldom do they require adjustment. Had a fellow with a G with same issue. He had to cut 1/2" out of rod.
 
With linkage connected to both gov. and carb.; without engine running; you should be able to lift rod either by hand OR by opening hand throttle to wide open position. turning loose of linkage and/or moving throttle to idle should result in gov. and linkage returning to idle position. If linkage does not "cycle" freely; check for binding in linkage where it goes in arm holes; bad angles on link rod; also; factory setting on linkage is; with throttle wide open; linkage should be about 1/2 hole long going into carb linkage. this is a good strting point. I have seen some that had to be adjusted with engine running. You may want to pull the gov. out of engine and verify that weights are moving freely and everything is connected
 

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