Tecumseh HM80 overreving

[zenapup]

I have a Tecumseh HM80-155481T 8HP engine that is on a 2001 MTD 24A-465A000 Serial Number 1I130C10015 Chipper/Shredder and when the engine is run above half throttle the engine will overrev like crazy, goes to about 2730 RPM's at half throttle which I know is normal, but with even the slightest movement to go faster it wants to go above 4000 RPM, idles fine at 1800 RPM.

Already tried:

Adjusting governor
Adjusting speed control screw
New speed control spring
Cleaned carburetor
Cleaned throttle and choke shafts

Any ideas?? Any help is apreciated!!

 

[ILENGINE]

sounds like the governor gear may be broke inside the engine and should be replaced. changing the gear may be fun because getting the chipper flywheel off can be a chore sometimes.

 

[zenapup]

I forgot to mention that the engine just got rebuilt, so the engine was off off the chipper, and the governor gear looked fine. Any other suggestions??

 

[JDgreen]

I forgot to mention that the engine just got rebuilt, so the engine was off off the chipper, and the governor gear looked fine. Any other suggestions??

Are you sure the carb jets are all set properly and there are no air leaks between carb and engine? I have a Tec HM100 on my generator and they are a very simple engine...can't figure out what your problem may be.

 

[ILENGINE]

There could be an air leak between the carb and engine. The governor adjustment has slipped or the gear is broken.

 

[zenapup]

Just checked the gear yesterday, and all gaskets were replaced when the engine was rebuilt, carb was also rebuilt, so I don't think that's the problem. Any other suggestions?

 

[ILENGINE]

when you reinstalled the carb after rebuild did you possibly get the governor linkage hooked in the wrong causing the governor to open instead of close the throttle. I have seen more then one tecumseh do that when someone hooks the linkage in the wrong side of the throttle plate on top of the carb. move the governor linkage toward the starter and see if the throttle is opening or closing. If the throttle is opening you are ok if you are closing then it is backwards.

 

[zenapup]

Could you explain this in more detail? I believe that this may be my problem so I'd like to know how to fix this.

 

[ILENGINE]

A lot of tecumseh carbs have multiple holes in the flat plate on top of the throttle shaft. The holes are for different applications. The plate on the throttle shaft has a small tab that hangs down and will butt up against the idle adjustment screw at idle. Now move the governor arm in the direction of the governor spring. If the tab gets closer to the idle adjustment screw the linkage is on the wrong side of the plate and needs to be put in one of the other holes one the opposite side of the plate. If you look closely you may see a hole that is showing some wear and that is the correct hole for the linkage to go into. If you need additional info send me your phone number in an email at ilengine@frontiernet.net and I will call you and talk you through it.

 

[zenapup]

Nope, this carb only has one, its Tecumseh part 640260. Any other ideas?