Engine races

Wed Jan 28, 2004 11:08 am

My 49 cub has a problem with the engine racing out of of control. Even when the throttle lever all the way back. It only happens when in neutral, foot on the cluch or sometime in reverse. If I put in gear and start to move it will slow to where it should be "under load". What would cause this? What should I do? Is it the governor? Thanks for any help.

Wed Jan 28, 2004 11:17 am

Sounds like the governor linkage is binding up. If you attempt to "throttle up or down" by pushing the arm at the carb, the governor should resist the change. If it doesn't, your problem is with the governor.

Sat Jan 31, 2004 8:21 pm

Thanks Bigdog on both replys. I haven't had a chance to take aprt the tie rods to see whats binding. I did check the governor for resistance while running. There was. I don't know what to check next. If I took off the governor how hard is it totake apart and what do I check for the might be wrong? I checked all my linkage and trottle on the carb and no binding. I left the cub for 2 min. on low RPM and when I got back it was racing so fast I thought it would blow up. Any other input would help alot. Thanks, Bob

Sat Jan 31, 2004 9:30 pm

If the governor linkage resists attempts to throttle up or down, I believe the problem is in the carb. I'd rebuild the carb before I messed with the governor.

Sat Jan 31, 2004 10:02 pm


You might want to check the spring adjustment on the front of the carb. Crank it in slowly, this may eliminate the racing. BE CAREFUL IF DOING THIS WHILE THE ENGINE IS RUNNING ( I STRONGLY RECOMMEND DOING IT WITH ENGINE OFF!!!) . Or replace that spring entirely as it maybe weak or broken off!!!

Sat Jan 31, 2004 11:31 pm

Here’s another one I can’t understand. I’ve had a throttle air door go wide open just after idle (when throttling up) because the governor weights would not go out and react against the governor spring. But, just setting there and idling; what is triggering the governor connecting rod to move? I know you didn’t have time to look but, was the rockshaft extension in the most rear position? (Wide open) If it was and you say the linkage is free towards the governor side, it has to be something with the governor. You said there was reaction when you throttled up the engine. That means the governor weights are moving. If the rockshaft is at the idle (closed) position it has to be the carburetor but, how is the air door opening when it’s screwed to a throttle shaft when it’s connected to a rockshaft in a closed position? I’m confussed, but that’s normal. :?

Jack Fowler

Sun Feb 01, 2004 7:41 am

I have change out the carb. Both have been rebuilt, 1 has been done twice. I still get the same results.

Sun Feb 01, 2004 8:54 am

I think but not sure .
Sounds like gov. linkage out of adjustment.(to much free play)
Or could you have hooked the gov. rod up wrong on throttle shaft.(so it works backwards).

One other question I would ask is does it hunt while you are working it?
If it does the gov. springs and where they hook gould be worn.

Sun Feb 01, 2004 10:26 am

The linkage looks to be homemade. It has the clevis part fpr the gov. end but someoneput a coupling in yje middle and made a U hook for the carb side.

Sun Feb 01, 2004 11:31 am

Now we're gettin' somewhere! :)

Wed Feb 04, 2004 4:25 pm

OK, Try this:

With the engine OFF, disconnect the throttle linkage at the governor arm. Set the throttle lever to FULL THROTTLE. Set the throttle plate to full on the carburetor. with the linkage attached to the throttle plate shaft lever, the other end should line up with the hole on the governor arm without having to move anything. Extend or shorten the linkage as needed to align these two parts. Install the shoulder pin and cotter pin....BINGO !! A working governor again!! It is my understanding this is to be done anytime the carb is taken off/swapped what-have-you, as it may not go back in exactly the same spot and the linkage adjustment is very important for proper operation. If you don't have the right linkage I suggest getting one from any of the several sources available. It is supposed to have a yoke on one end(where it attaches to the governor lever) and is threaded for precise adjustment. GOOD LUCK !!