won't turn over with spark plug in

[Old Ern]

Hi. I am new here.
I have a Stiga with a Briggs and Stratton model 310000 engine.
Will turn over freely with out spark plug, fit spark plug, starter will not take it
over compression. new battery , new starter motor
is there a decompression unit fitted somewhere ?
How do I check the timing as I think it is trying to fire too early when it does spin.
Thank you

 

[ILENGINE]

First thing to check is to remove the OHV cover and set the intake to .003-.005 and the exhaust to .005-.007 keeping in mind that the intake valve is the bottom valve when looking down from the flywheel side of the engine. After making the adjustments turn the engine over by hand while watching the intake valve for a slight bump off seat just before TDC compression stroke to make sure the compression release is working.. If found to not be working then would indicate broken compression release on camshaft, and your options at that point is to try to find an aftermarket camshaft that may not fit properly or wait like the dealers for OEM camshafts which I have had on backorder since April.

 

[Old Ern]

First thing to check is to remove the OHV cover and set the intake to .003-.005 and the exhaust to .005-.007 keeping in mind that the intake valve is the bottom valve when looking down from the flywheel side of the engine. After making the adjustments turn the engine over by hand while watching the intake valve for a slight bump off seat just before TDC compression stroke to make sure the compression release is working.. If found to not be working then would indicate broken compression release on camshaft, and your options at that point is to try to find an aftermarket camshaft that may not fit properly or wait like the dealers for OEM camshafts which I have had on backorder since April.

Thank you, will check in the Morning.

 

[slomo]

How do I check the timing as I think it is trying to fire too early when it does spin.

Remove top fan shroud. Look for the flywheel key and the groove it goes in. Key shouldn't be mangled in any way. The groove should line up with the key slot on flywheel and crankshaft.

 

[Old Ern]

Remove top fan shroud. Look for the flywheel key and the groove it goes in. Key shouldn't be mangled in any way. The groove should line up with the key slot on flywheel and crankshaft.

THANK YOU

 

[Old Ern]

Thank you, will check in the Morning.

You were right, and they are like Rocking Horse Shit to fined. Thanks again. E

 

[hlw49]

First thing to check is to remove the OHV cover and set the intake to .003-.005 and the exhaust to .005-.007 keeping in mind that the intake valve is the bottom valve when looking down from the flywheel side of the engine. After making the adjustments turn the engine over by hand while watching the intake valve for a slight bump off seat just before TDC compression stroke to make sure the compression release is working.. If found to not be working then would indicate broken compression release on camshaft, and your options at that point is to try to find an aftermarket camshaft that may not fit properly or wait like the dealers for OEM camshafts which I have had on backorder since April.

After you adjust the valves and check the compression release as ILENGINE stated and found to be bad turn it backward against rotation by hand until you feel compression in this direction you will probably be able to start it this way. If not you probably have a cam the lobes or cam gear have slipped on the cam shaft.

 

[Old Ern]

Thank you, will check in the Morning.

After you adjust the valves and check the compression release as ILENGINE stated and found to be bad turn it backward against rotation by hand until you feel compression in this direction you will probably be able to start it this way. If not you probably have a cam the lobes or cam gear have slipped on the cam shaft.

Thank you. I am fitting a new cam shaft as the old one has lost it's decompression cam. so hopefully all will be good.