OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Briggs carburettor setup problems

Hello to all,
I was using an older Rover self-propelled walk-behind mower the other day, when the revs suddenly screamed off into the red zone - mechanical governor catastrophic failure. Opening the crankcase revealed pieces of governor everywhere. Machine is a Rover model 32113, powered by a B&S 5 HP IC engine, model details - 132922 - 0134- 01 (code 92040307). The old pulsa-jet type carburettor.

I have replaced the governor/oil slinger with OEM parts, and given the carburettor an overhaul via the standard OEM kit. Renewed engine starts up OK, will run at high revs OK, but idle speed seems quite high - engine was running mounted on cutting deck with mower blades in place, unloaded, on a hard surface.
I note that the governor spring opens the throttle in following the throttle cable action, but the fast idle set spring seems to hold the throttle too far open when I try to reduce engine RPM to idle, even when the throttle cable is set at a point just above spark plug shortout point. I attach a couple of photos of the setup for information. (I also note that the B&S illustrated parts for this series of engines does not list the fast idle spring as being fitted to this model - maybe a misprint/typo?.) The engine was definitely fitted with one prior to governor failure. Available B&S information indicates that this engine model is 20 years old - I do not know how old the governor and fast idle springs are, as I inherited this machine. The mechanical governor system arms and linkages were set up as per B&S guidelines, and appear free to move without any binding. Either I have incorrectly installed the links and springs at the carburettor end or the springs are not OK. (In the photos the throttle cable is set at the minimum throttle opening position.)

All helpful suggestions welcome and acknowledged.

Thanks,

mustang

That engine was built on 3 April 1992, and is a third design generation engine, with the automatic choke on the PulsaJet. It should be a nice engine.

As I understand it the only engines fitted with the second (idle) governor spring are the ones with "governed idle". The later governed idle engines did not have an idle speed screw, and I think all of them had a special bracket to serve as the anchor for the idle spring, so your engine does not seem to be a governed idle engine and hence should not have the second spring. (Having said that, there's no telling what configurations might have been built in the factory whilst using up the last of the parts for the non-governed-idle engines.) The idle speed of governed idle engines is adjusted by bending the bracket on which the static end of the idle spring is mounted, as shown in the B&S manual:


So, you can remove the idle spring and set the idle speed with the idle speed screw, or if you wish you can find or make a governed idle spring anchor bracket, so you could have the choice. Idle speed on most of those engines should be 1,750 rpm. Maximum speed is 3,000 rpm on the vertical crankshaft engines.

I notice the adjustable idle stop on your engine is screwed all the way in, which would result in a very high idle speed even without the governed idle feature.

grumpy,

Thanks for your post - I removed the fast idle spring and engine performance improved immediately. I can now get it to idle at approx. 1500 RPM (est.) and maximum RPM appears to be about 3000 RPM (est.) - engine unloaded.
I do notice that with this engine the operating band (S - F) indicated on the remote throttle control appears quite narrow, a little above F or a little below S results in the engine staggering immediately and stopping soon after. I suppose that could be just the geometry of the cable linkage/hookup.
Incidentally, I have another query in relation to the mower itself, but I suppose that should come under another heading - so I will consider this post closed, and open a separate enquiry.

Thanks again,
mustang

To set up the speed control you need to look at where in the movement range of the lever the choke begins to close (this has to be the limit of high speed running) and where the kill switch contact is engaged (this has to be the limit of low speed running). Your working range is from one of these points to the other. The idle speed should be 1,750 rpm.

Thanks for reporting back - I'll close this thread.