Decompressor issue? Need advice

[Gregg N]

Hello my mower is a simplicity with a commercial Brighs and Stratton 12.5 hp flat head engine. My mower has poor performance and when I checked the valve clearance the intake valve had none. It was touching the push rod at TDC. I set the valve clearance but by doing so made a slight mistake and made the clearance double what it should be ( the manual is right it is really easy to do . ) I decided to put it together in the mean time while I wait for a new valve figuring it would just be noisy.

Now when I turn the key the starter refuses to continually turn the fly wheel. I am wondering if these engines have decompression on the intake when starting???? You can tell the engine compression is stopping the starting momentum.

That is the only reason I can think why my starter is having trouble turning the engine over. ( It's not an electrical problem guaranteed!)

 

[bertsmobile1]

Yes.
If the vave lash is too big the decompressor can not work and the starter will not be able to turn over the engine.
Some times you can get lucky if you manually turn it just over TDC then hit the starter it will fire in the first stroke or have enough momentum to swing through TDC a second time.
alternatively you can loosen the spark plug a little to do the same thing then after the engine has run for 5 minutes and warmed up, tighten it ,
Usually when hot it will start.
Or you can try tightening the plug with an open ender with the engine running , just hope the insulation is good ,wear rubber soled shoes and do not touch the mower anywhere other than the plug or else :shocked:
Next time.
Face the end of the valve stem by hand.
I use an oilstone.
Takes a little while but it is very hard to judge a 0.001" cut.