TOO MUCH COMPRESSION - BRIGGS 21 HP INTEK TWIN OHC

[Ed Becker]

I have a 21 HP OHC about 8 years old. It was given to me - not in very good shape. Cleaned it up and
I got it going good - ran all summer, and then hard starting like a low battery. I adjusted the valves first, installed new solenoid and replaced the stator and changed the battery. Still enormous compression. It did not change a thing.
I only use it for towing a garden trailer - no mowing.

I opened up the sump and I took out the Cam. But I noticed that this cam doesn't have a Compressing relief spring on the cam..
I called my local small engine shop and he said the Compression relief is built in.
I looked over my camshaft and it looks good to me,,,

My question is this, is there something I'm missing? the pushrods look straight and the sump was very clean.....so how do I relive this compression issue. BRIGGS AND STRATTON MODEL # 407577 0292 E1
I think this engine is still in pretty fair shape....STUMPED

 

[Scrubcadet10]

Let's start with the engine model number so we can see what you have,exactly.

 

[Ed Becker]

Let's start with the engine model number so we can see what you have,exactly.

BRIGGS AND STRATTON MODEL # 407577 0292 E1

 

[Nelson_Donnell]

Your problem might possibly be fuel leaking into the cylinders due to a worn needle and seat in the carb, allowing fuel to perculate into the intake manifold.. Short of replacing the carb, you could put an inline fuel shut-off valve in the fuel line and make sure you turn it off whenever you shut the engine off.

 

[Fish]

On the old L-heads, a common over-compression problem turned out to be a build-up of carbon in the combustion chamber was the problem, it kicks up the compression ratio a bunch. Maybe it is the same here.

 

[7394]

On the old L-heads, a common over-compression problem turned out to be a build-up of carbon in the combustion chamber was the problem, it kicks up the compression ratio a bunch. Maybe it is the same here.

Was thinking same thing as a possible.

 

[StarTech]

With is it being 8 yrs old it is a good possibility that the starter bushings or brushes are worn out and the starter itself is dragging.

 

[Rocky J]

I can think of two things that have gave me fits. The flywheel key has smeared from a backfire or abrupt stop which throwed off the timing just enough and starter or starter gear or flywheel was changed and do not match now, if the starter gear is plastic then the flywheel gear needs to be plastic or aluminum but the steel ring gear on flywheel needs to have a steel gear on starter, The number of teeth are different, like 14 tooth on steel and 16 on plastic?? but will give you that low bat or bad starter, bad compression release thoughts.

 

[Rivets]

Reported

 

[Fish]

Hard to imagine anyone clicking on any of those links!