OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines 5 HP Briggs & Stratton Over Revving

Hi guys, I have a Briggs 5HP 131432-0197-01-84062707 engine powering a 24" Scott Bonnar Super Cut.

Firstly I need some help with the ID of the series of the engine so I can get a hold of some carby spares and a throttle cable return spring, I must say its a little confusing with so many models and numbers ETC.

Also this particular engine just wants to run at max RPM no matter the throttle setting, governor position or butterfly opening or closing. The only way to get it to run at any sort of reasonable RPM is to partially choke it.

I posted some photos of the governor spring set up which appears to be the same as a spare 5HP (132432-0214-01-86042107)that I have on the shelf so I don't think I am missing any linkages or springs?

The inlet manifold appears intact and doesn't appear to be sucking oxygen, if anyone could help with engine ID of both engines and a possible fix to the over revving I would be very appreciative. Cheers Glenn.

The idle speed screw is pushed way too far in, that is the black/silver screw in the last picture on the throttle shaft, unwind it most ofthe way out and it should help bring the rpm's down.

Thanks Joe I will try and start it first thing in the morning, the screw was only set at one and a half turns from being fully in. Cheers Glenn.

The two screws marked in yellow need to be 1.5 turns out, however the one in red is the idle speed screw, at present time it is in so far it is jamming the butterfly over half way open, to start off with back it off to the point where there is only a couple of threads sticking through and turn it in half a turn at a time until you have a reasonable idle speed without it stalling.

Here is the illustrated parts list for your engine:
http://bsintek.basco.com/BriggsDocumentDisplay/Z6mlsFVJ1DajI.pdf

As Joe said, you have the idle speed screw set as high as possible, so the engine will probably be running above its maximum allowable speed when there is no load on it, regardless of where you set the speed control. Just back out that screw and at least one cause of over-revving will be cured. If the engine still over-revs when it is run with the handlebar speed control set to maximum, there will be a second problem, with the governor itself, but we will need some more pictures to try to diagnose that. Usually problems are caused by just one fault though, and the idle speed setting will be causing the problem you have described when there is no load on the engine.

I hope you have not damaged the engine running it with the idle speed set at maximum.

Hi Grumpy, thanks also to Joe for the clear photos.

Thank you both so far the help, this engine threw me out a bit I must say as I picked it up supposedly running well and got a bit blind sided when I first cranked it up to hear it nearly rev its gizzard out, thank goodness for the kill lever..

Ok.. I've got the engine idling nice and coming up in the rev range well, on idle there is no 'hunting' of governor.

At higher Rpm the governor cuts in out a bit much I think. I know these things are fairly precise and I'm thinking its a bit of a balancing act with the fuel air mixture though to get it just right?

Glenn, if the engine speed cycles continuously, say every 2-5 seconds, that is called "hunting" and is usually caused by lean mixture. (It can be due to friction or jamming in the governor mechanism, but that is relatively unusual.) Your carburetor appears to be a small two piece Flo-Jet, and the main mixture adjustment is the screw that sticks out from the lower left of the float bowl at a 30 degree angle to the vertical. With the engine running and hunting, turn that screw anticlockwise a quarter of a turn and wait a few seconds to see what happens. If it still hunts turn it the same way another quarter turn. If it still hunts after that, you are going to have to look for a fault: either an air leak or dirt in the carburetor.

Hi Grumpy, have done exactly as you have suggested and spot on mate, I am so happy now. The motor is an absolute beauty, easy to start and runs really quiet, time to change the oil and it should be set for the season I hope.

What oil would you recommend for this engine? and is their anything else I should service other than this, the spark plug and air filter?

Regards Glenn.

Thanks for reporting back Glenn - a thread that ends up with no conclusion is frustrating for future readers.

For the usual range of daily temperatures Briggs recommends a straight SAE 30 oil (not multigrade) with an automotive rating, such as SJ etc. If you use multigrade it will burn more oil, though it won't actually do any harm.

When you drain the oil, get the engine warm first, then tilt the mower steeply toward the drain (usually the filler hole, but there is a drain plug underneath the engine as well) so that the drain is the lowest point on the engine. This is so that as much of the accumulated sludge comes out as possible. Leave it tilted and draining for half an hour or so. Clean and gap the spark plug, and test the ignition by pulling the starter with the spark plug clamped to a metal part of the engine - expect a steady series of blue sparks. It is useful to check the tappet clearances, with an unfamiliar engine - behind the valve chest cover, near the crankcase. Check that the cooling fins are clear of grass and debris, both on the cylinder and the cylinder head. If it is running well without smoke and there is no oil around the muffler, I personally would not pursue it further than that.

Thanks again Grumpy, this motor doesn't appear to blow smoke or run oily and only time will tell if it usually burns any oil, but I think given this is a pretty big unit for my suburban 15m x 10m lawn I don't think think she is going to suffer from too much heat exhaustion either man she's definitely got a bit of grunt too, I have a really steep section of lawn down to a foot path and even just off idle (any faster and I'm almost running) she pulls like a Mack truck..

Thanks for the info on the tappets as well.

Grumpy I was so happy with the resurrection of this machine and the couple of days work I put into it so far that I had a fella swing by today and pick it up for a new bed knife and cylinder grind, cant wait to get it back, I totally enjoy clipping my lawn with this bit of heavy duty kit..

Will probably look at doing a nice make over on her next winter now that she is up and cutting like new one, I just love these old machines they were designed and built well compared with today's throw away junkers.

Just want to extend my thanks again to both you and Joe.. Cheers Glenn.

Thanks Glenn, I'll close this thread. If anyone needs to post to it, just PM a moderator.