Briggs 17hp Model 314777 surging

[jtlambrecht]

Hello All,

I've looked through some similar threads with this problem but none were specific to my engine. Symptoms: The motor will start just fine, but runs with constant surging. I can manipulate the choke some and get it to smooth out pretty good, or I can hold the governor arm in place and it will also run smoothly. I've had the entire motor out twice and opened it up to check the actual governor itself, and I can't see anything wrong with it. Timing is correct, cam gear is in proper position on the crank gear. It has a Nikki Model 697202 carb which I've also had apart and cleaned thoroughly. This lawn tractor belongs to my brother, and it sat outside, unused, for 7 or 8 years before he asked if I'd get it running. Most answers I've read on this similar problem were carb-related (i.e. cleaning, gaskets, seals, etc.) Has anyone ever had the governor itself actually fail? I am hoping to not tear the motor apart again, perhaps just a rebuild kit for the carb? Any advice would be appreciated, and also if anyone knows where I can purchase a rebuild kit for that Nikki carb. Would like to try that first.

 

[Rivets]

With that carb I only have about a 50% success rate when cleaning and rebuilding. I service at least one carb a day, so I do have a bit of an insight into what I say. If it has sat outside for the length of time you posted, I would recommend that you just replace the carb. Even if you are doing all the work yourself, buying a rebuild kit and not solving the problem will have you back replacing the carb. Depending on the situation it is better for me to replace than to rebuild. Just my recommendation.

 

[bertsmobile1]

Hello All,

I've looked through some similar threads with this problem but none were specific to my engine. Symptoms: The motor will start just fine, but runs with constant surging. I can manipulate the choke some and get it to smooth out pretty good, or I can hold the governor arm in place and it will also run smoothly. I've had the entire motor out twice and opened it up to check the actual governor itself, and I can't see anything wrong with it. Timing is correct, cam gear is in proper position on the crank gear. It has a Nikki Model 697202 carb which I've also had apart and cleaned thoroughly. This lawn tractor belongs to my brother, and it sat outside, unused, for 7 or 8 years before he asked if I'd get it running. Most answers I've read on this similar problem were carb-related (i.e. cleaning, gaskets, seals, etc.) Has anyone ever had the governor itself actually fail? I am hoping to not tear the motor apart again, perhaps just a rebuild kit for the carb? Any advice would be appreciated, and also if anyone knows where I can purchase a rebuild kit for that Nikki carb. Would like to try that first.

:welcome:

Well if you have really searched the archives for surging you will have seen endless people saying
SURGING ON A GOVERNED ENGINE IS ALWAYS FUEL RELATED
The mechanism is the governor opens the throttle so the engine accelerates but the mower can not supply enough fuel to maintain running at the higher speed so the engine starves and slows down.
The governor responds to the lower speed and allows the throttle to open up again and because the engine is now going slower and has enough fuel it will accelerate again till it get to the limit of the fuel supply, where it starves so slows down again.
This cycle repeats at infinitum.
Depending upon the amount of fuel available an engine can surge anywhere from idle to WFO
SURGING PROVES THAT THE GOVERNOR IS WORKING PROPERLY

IF when you are bypassing the governors control by holding the governor arm, you steadily increase the revs at some point in time the engine will go into a lean missing situation.
The only reason the engine runs smoothly while you are holding the governor arm is your finger is effectively changing the governed speed, exactly the same as if you closed down the throttle till the engine ran smooth.

So somewhere between the fuel tank cap & breather and the inlet valve some thing is preventing a combustable ratio of fuel to air entering the cylinder


A governor GOVERNS the speed.
an engine with a failed governor will attempt to rev as fast as it can then go BANG in a big way from over reving.
Without the governor most mower engines will accelerate up to the limit of the carbs choke which is around 8000 rpm
Unfortunatly most will self destruct somewhere between 4000 rpm & 6000 rpm cause the rods and counter weights can not run at those speeds.

 

[Tommy]

bertsmobile1, Sweet information! Thanks!


Tommy

 

[bertsmobile1]

bertsmobile1, Sweet information! Thanks!


Tommy

The best information came from Rivets.
Looks like we were on line at the same time or my post got delayed.
Happens some times my posts seem to get stuck in the either for a day or so.