B RPM surging - Gene Bender

[Matt E.]

Gene,

My B wants to surge at WOT. The tractor set in the woods for I don't know how many years. What is the first step to this issue? Is the govenor properly oiled? Could it be gummed up?

Check linkage adjustment first and then to the govenor? Never messed with it, just hooked it back up. It runs fine at anything but WOT.
 

[Bob M]

With the engine stopped and the governor handle at "idle" does the gov to carb linkage move freely? If not, find and correct whatever is causing it to be stiff.

If the linkage is free, problem is likely carburetor adjustment (too lean at full throttle).

With the engine warmed up and running at full RPM, try pulling the choke out SLOWLY. If you find a choke position that makes the surging go away you've found the problem.

Solution is to open the carb load needle 1/4 turn at a time until the surging disappears. However if after opening the load screw 2 - 3 turns the engine still surges it's time to go inside the carb and clean it out.
 

[old]

Almost bet your carb main jet is clogged up and needs cleaned out. If it is like most carbs on the B the main jet is not adjustable so you remove the cover plug and let fuel flow out of it and also stick a small wire in to clear it out
 

[Matt E.]

My feeling is that it is in the governor. When it was doing it, the linkage to the carb was moving back and forth, speeding/slowing the motor. I grabbed the linkage by hand and sped up the motor. It didn't hesitate or run poorly, just sped up as it should. Something wore or stuck in the govenor?

We had the carb completely apart and soaked it in some nasty stuff. Not to say there couldn't be a chunk of dirt in it but it runs and starts great. Just surges at WOT.
 

[gene bender]

Have you set the linkage going to the carb. And like the other post says mite be a plugged passage in the power circut in the carb.