Riding mower wont start. Flywheel turns full turn and stops.

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William2146

Forum Newbie
Ok, I have a craftsman riding mower, model 917.258523. It ran fine a week ago. I had to replace the flywheel because the plastic one that came on the motor started cracking and messing up the starter gear. I replaced the flywheel and now when I turn the key the motor turns over a full turn and then stops. If I hold the key it will continue to make a full turn and stop. the motor pauses for about 5 seconds then rotates again. I can spin the motor both ways by hand fine. I checked the spark plug and there is plenty of spark. I also thought it might have been the battery but used jumper cables and hooked it up to my car and it did the same thing. I checked the key on the crankshaft and it is still entaced. What am I missing or what can I try. Thanks
 
I am certain that the flywheel is NOT plastic. Perhaps the fan or fins are plastic. If you removed the entire flywheel, did you remember the flywheel key? This is what times the ignition
 
The key that you are talking about is the one that holds the flywheel assembly to the crankshaft, correct. If this is the one your talking about I did put it in and just checked it to see if it was sheared and it isn't.
 
Check your valve clearances.
Valve Clearance | Briggs & Stratton

If ok then the decompressor on the camshaft could be broken and not allowing engine to turn past conpression stroke.
A decompressor lets excess pressure out of engine to allow starting.

Inlet should be 0.003"-0.005"
Ex should be 0.005"-0.007".
 
I will check the valves. I need to buy a gauge for it. In the mean time. Where is the decompresser and is there any way to test it.
 
William2146 said:
I will check the valves. I need to buy a gauge for it. In the mean time. Where is the decompresser and is there any way to test it.
Click to expand...

The decomp is on the end of the camshaft which is in the engine.
The only way to test it is checking valve clearances.
With the rocker cover off and turning the engine by hand the valves should go up and down.
Looking closely 1 valve should open then close and then it should open/close ever so slightly like a small bump.
Thats the decomp working.
If it doesnt bump then the decomp may be broken and you would need to replace the camshaft.
Read the attachment i posted about setting valve clearances carefully.
You only need feeler guage.
 
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