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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 27477
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a briggs and Stratton engine on a lawn tractor. It is

Customer Question

I have a briggs and Stratton engine on a lawn tractor. It is a 2 cylinder 25 HP. The engine goes overspeed. It still goes extremely fast with the governor being held and the carb butterfly seems to be closed????
JA: Can you guesstimate how old the engine is? And has it done anything like this in the past?
Customer: Engine is probably ten to 15 years old and has not done anything like this in the past.
JA: Do you plan on doing the work yourself?
Customer: Yes,
JA: Anything else we should know to help you best?
Customer: I had a problem originally with what appeared to be a stuck ring which I was able to free up with oil.
Submitted: 11 days ago.
Category: Small Engine
Expert:  Curtis B. replied 11 days ago.

Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!

Expert:  Curtis B. replied 11 days ago.

Engine model number? Is the throttle flap in the carburetor still attached to the throttle shaft? shaft not broken? If not, problem is the internal governor parts.

Customer: replied 11 days ago.
446777
Expert:  Curtis B. replied 11 days ago.

Late model twin OHV engine. So is the carburetor throttle shaft and flap ok, not separated?

Customer: replied 11 days ago.
The governor is restrained holding the carb butterfly closed. Can see the linkage and it shows closed. Still getting a high speed.
Expert:  Curtis B. replied 11 days ago.

if the carburetor butterfly is closed, there should be no high revs! You are looking at the throttle, not the choke flap?

Customer: replied 11 days ago.
I am looking at the throttle. Am restraining the governor with a high tension spring and it is holding the linkage closed. I haven't checked the throat to see the flap condition. Can a vacuum leak cause this type of thing with the butterfly closed?
Expert:  Curtis B. replied 11 days ago.

It would have to be a big vacuum leak! Never saw one that did this, usually it is broken throttle shaft.

Customer: replied 11 days ago.
Are you talking about the throttle shaft?
Customer: replied 11 days ago.
I believe that you have confirmed that the speed is not possible unless the carb butterfly is open. I was wondering if there was something that I was missing. Will check the throttle shaft. Thank you.
Expert:  Curtis B. replied 11 days ago.

let me know!

Expert:  Curtis B. replied 5 days ago.

I see question is still open, did you find problem?