Briggs & Stratton 21 HP Centrifical Compression Relief Valve

Gbarry

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  • / Briggs & Stratton 21 HP Centrifical Compression Relief Valve
I have finally diagnosed a staring problem with my 5 year old Briggs motor. I have found out it is a common issue with these motors that the compression relief for the starting cycle does not open causing the starter to stop after a slight turn of the fly wheel.


I always thought Briggs was a strong motor until this happened. Has anyone repaired this before?
 

Boobala

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  • / Briggs & Stratton 21 HP Centrifical Compression Relief Valve
Have you pulled the sump off to make sure ??..... sounds like it might be in need of a valve adjustment to me ..
 

Catherine

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  • / Briggs & Stratton 21 HP Centrifical Compression Relief Valve
:welcome:

Welcome to the forum!

I'm going to move this thread over to our Briggs & Stratton section.
 

Tinkerer200

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  • / Briggs & Stratton 21 HP Centrifical Compression Relief Valve
When asking an engine question, you should post the model number so we know what B&S engine we are talking about since there are more than one 21 hp. Assuming you might be talking about the 33 Series single cylinder Intek, valve adjustment is the first thing you should check. I can send you detailed instructions on adjusting the valves which includes a test for the compression release. Will include a Service Manual as well. By the way, in the intense competition B&S is not the only one to cut corners. Kohler put out a total pc. of crap line. B&S has a commercial line, Vanguard, and a home owner's line, Intek.

Walt Conner
wconner5 at frontier dot com
 

Gbarry

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  • / Briggs & Stratton 21 HP Centrifical Compression Relief Valve
Thanks Walt, I check the valves and I got the clearance but I will follow your procedure and see if I missed any thing.

The motor will start and run every time when I put my hand over the air intake for a few seconds and then let it complete a few revs.
 

bertsmobile1

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  • / Briggs & Stratton 21 HP Centrifical Compression Relief Valve
The starters fitted are quite weak deliberately.
Thus when you get a hydro lock, which is very common usually the starter just stalls, doing little to no damage on a new ( Warrantied ) engine and generally blowing the head gasket on an older unit.
A stronger starter can & does bend con rods which once the engine starts running destroys the entire engine.
Seen way too many blocks destroyed cause the owner fitted a stronger starter.
 
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