Cub 129 engine revs to high

capri17 · #1 05-04-2012, 08:19 AM

Hey everyone I am new to this site and looking for some info on my 129 cub cadet. I just completely rebuilt the engine. had the block bored valve job done. Installed new piston rod valves did it all over mint. I got it running for the first time yesterday it fired right up and ran pretty smooth. My problem I am having is if you put the throttle anything off idle the engine take right off. I can see in the carb and the throttle blade is only open like 1/4 but it runs like it at least 3/4 throttle. I checked the governern and that is set right and working. The carb does have a good amount of play in the throttle shaft. I am wondering if because the shaft is so loose that its just sucking to much air causing to rev high. Or do I have the card set to lean. What are your guys thoughts thanks

Methos · #2 05-04-2012, 09:15 AM

Quote:

Originally Posted by capri17

Hey everyone I am new to this site and looking for some info on my 129 cub cadet. I just completely rebuilt the engine. had the block bored valve job done. Installed new piston rod valves did it all over mint. I got it running for the first time yesterday it fired right up and ran pretty smooth. My problem I am having is if you put the throttle anything off idle the engine take right off. I can see in the carb and the throttle blade is only open like 1/4 but it runs like it at least 3/4 throttle. I checked the governern and that is set right and working. The carb does have a good amount of play in the throttle shaft. I am wondering if because the shaft is so loose that its just sucking to much air causing to rev high. Or do I have the card set to lean. What are your guys thoughts thanks

I know you've set the govener but I would double check it. It needs to turn CCW while holding the throttle wide open. To me it sounds like you set it by turning the govener shaft CW. I made the same mistake before.

It takes two people to make it easier.

capri17 · #3 05-04-2012, 09:42 AM

Thanks for the info yea thats what I did turned the shaft counter clockwise and held the throttle wide open. So that is set ok something else is not right

capri17 · #4 05-04-2012, 12:39 PM

Anyone else have any ideas thanks

_DX3_ · #5 05-04-2012, 03:45 PM

The throttle shaft being loose will usually make them surge and hard to adjust, if it is real bad it could be the culprit. They are pretty easy to fix. I picked up the parts I needed to do mine at the local Ace Hardware Store. I would look into a good carb rebuild if you didn't do that when you rebuilt the engine. I am taking for granted you did replace the governor and components with all new stuff when the engine was rebuilt?

capri17 · #6 05-04-2012, 05:09 PM

Ok what parts do you need to fix it. Is there just a bushing on the top that wears out and need to be replaced. I did not replace the governor. I did remove it and inspected it everything looked good and was working smooth. Its not pulling any harder than needed and works when you out under a load. I am thinking thats its either sucking to much air or just not adjusted right.

_DX3_ · #7 05-04-2012, 07:45 PM

Quote:

Originally Posted by capri17

Ok what parts do you need to fix it. Is there just a bushing on the top that wears out and need to be replaced. I did not replace the governor. I did remove it and inspected it everything looked good and was working smooth. Its not pulling any harder than needed and works when you out under a load. I am thinking thats its either sucking to much air or just not adjusted right.

Take a look at this link:
http://www.onlycubcadets.net/forum/s...ad.php?t=10329

capri17 · #8 05-05-2012, 10:03 AM

Ok cool thanks hopefully I can get this figured out.

Matt G. · #9 05-05-2012, 10:54 AM

A worn throttle shaft will not cause the engine to run away...it'll cause it to hunt around and not maintain speed well within +/- 100 rpm or so.

Do you have a tach? Setting the governor by ear only works if you know what it's supposed to sound like at 3600 rpm. Until you're able to do that, use a tach so you actually know how fast it is turning. Do you have the high-speed stop bracket installed? Is the governor spring in the correct holes?

If yes for all of those things, then it's possible the 'initial adjustment' in the manual doesn't quite get the job done on your engine. Go through the adjustment as outlined in the manual again, but instead of tightening the arm on the shaft, rotate the arm and shaft together towards the carb a bit, perhaps 1/4" at the top end of the governor arm, then rotate the shaft CCW until it stops again, then tighten the arm on the shaft. This will make the governor kick in at a lower RPM. I've had to do this on one of my tractors, and other people have had the same problem from time to time. Another thing to check is to make sure the arm isn't moving on the shaft, as this sometimes happens if the arm got loose and wore out or was really overtightened by some ham-fisted mechanic in the past. draw an alignment mark across the shaft and arm with a sharpie, nail polish, torque seal, etc. then run it and make sure that there is no relative motion between the shaft and arm.

capri17 · #10 05-05-2012, 03:05 PM

Ok guys I had a chance to mess around with it today. I reset the governor and i forgot to put the L bracket throttle stop. I had the motor apart for a couple weeks and you always forget how something goes together. I did that and the throttle is working fine no problems. Now because the throttle shaft is worn is does searching around. I will get some bushings and fix that. thanks for all your help.