Export thread

725EX Governor problem?

#1

B

bitdemon

Hi there - I had the misfortune to hit a small unseen stump in the weeds in my Victa (from down under) 19" mower. It's got a B&S 725EX 163cc 104M02-0216-H5 engine DOM 08 22 2018 proudly made in the USA. After the hit, the engine went into overspeed and the throttle control could only shut it down.
So, I'd appreciate a parts diagram to have a look at to see what I'm up against, and any insights as to what needs doing would be much appreciated as I really only want to have to tear it down as much as I have to!
PS: As a long-time lurker on this forum I think it's bad form not to post the results to provide closure, but it might be a fair while before I get around to fixing it!


#2

ILENGINE

ILENGINE

Here is a parts diagram for your engine https://www.partstree.com/models/104m02-0216-h5-briggs-stratton-vertical-engine

I would start with removing any covers that restrict access to the top of the carb, and check to make sure that a sudden joit didn't jam the throttle control on the carb. Make sure the throttle butterfly in the carb rotates. It has been awhile but there was an issue with one of the Briggs older engines where the throttle butterfly in the carb could overcenter causing a stuck at full uncontrolled throttle. It looks like from the carb diagram that this carb also controls the choke opening on startup, so don't overlood the chance that the choke has jammed the throttle open.

Beyond that it could be possible the jolt could of broken the governor gear but that would be a low possibility. And also if the engne came to a sudden stop when this happened it could of partially sheared the flywheel key which shouldn't cause overspeed, but can cause other issues.


#3

B

bitdemon

ILENGINE said:
Here is a parts diagram for your engine https://www.partstree.com/models/104m02-0216-h5-briggs-stratton-vertical-engine

I would start with removing any covers that restrict access to the top of the carb, and check to make sure that a sudden joit didn't jam the throttle control on the carb. Make sure the throttle butterfly in the carb rotates. It has been awhile but there was an issue with one of the Briggs older engines where the throttle butterfly in the carb could overcenter causing a stuck at full uncontrolled throttle. It looks like from the carb diagram that this carb also controls the choke opening on startup, so don't overlood the chance that the choke has jammed the throttle open.

Beyond that it could be possible the jolt could of broken the governor gear but that would be a low possibility. And also if the engne came to a sudden stop when this happened it could of partially sheared the flywheel key which shouldn't cause overspeed, but can cause other issues.
Click to expand...
Well, checking the linkages and butterfly is easy enough. I had a panic attack it might have been the internal governor gizmos, but I guess with a bit of luck... I'll get onto that tomorrow.


#4

B

bitdemon

Thunderstorms yesterday, 103 degrees F today, but I still managed to get out and take the covers off the top and carb. The culprit was a mud wasp that had built a nest through the throttle linkages at the carb. Those critters build nests absolutely everywhere on equipment. Part of the mud nest was broken. I'm guessing that the shock had broken part of the mud nest, and when the carb had gone WOT, the broken part of the nest had locked the throttle lever. Picture attached - unbelievable but I cleared it all away and now all is good. Thanks very much for the advice - likely saved me some unnecessary disassembly!

Attachments





#5

Tiger Small Engine

Tiger Small Engine

bitdemon said:
Thunderstorms yesterday, 103 degrees F today, but I still managed to get out and take the covers off the top and carb. The culprit was a mud wasp that had built a nest through the throttle linkages at the carb. Those critters build nests absolutely everywhere on equipment. Part of the mud nest was broken. I'm guessing that the shock had broken part of the mud nest, and when the carb had gone WOT, the broken part of the nest had locked the throttle lever. Picture attached - unbelievable but I cleared it all away and now all is good. Thanks very much for the advice - likely saved me some unnecessary disassembly!
Click to expand...
That is one of the weird things that can happen. I wish more people would let us know what the final problem and solution was both on here, and from customers I have very occasionally that I cannot determine how to repair their equipment. It is a continual learning process in life.


#6

ILENGINE

ILENGINE

bitdemon said:
Thunderstorms yesterday, 103 degrees F today, but I still managed to get out and take the covers off the top and carb. The culprit was a mud wasp that had built a nest through the throttle linkages at the carb. Those critters build nests absolutely everywhere on equipment. Part of the mud nest was broken. I'm guessing that the shock had broken part of the mud nest, and when the carb had gone WOT, the broken part of the nest had locked the throttle lever. Picture attached - unbelievable but I cleared it all away and now all is good. Thanks very much for the advice - likely saved me some unnecessary disassembly!
Click to expand...
Thanks for letting us know what the solution was and it was that simple.


#7

S

slomo

Pull off the top engine shroud. Clean the cooling fins as well as the entire engine block. Yearly maintenance in your engine manual. Neglect this and risk engine damage.


#8

B

bitdemon

slomo said:
Pull off the top engine shroud. Clean the cooling fins as well as the entire engine block. Yearly maintenance in your engine manual. Neglect this and risk engine damage.
Click to expand...
Don't worry - I remembered and inspected all the cooling fins when the shrouds were off. Pretty hard to ignore your dire warnings on each of your posts! :)


Footer Links 1

Top