Engine turns over w/o plug in but not with plug in.

[Fritzm]

Have a Craftsman lawn tractor (917-274391) with B&S 18.0 HP Intek. After winter went to start and seemed like either starter was weak or engine was binding. Opened starter and plenty of service area left on brushes. Next adjusted valves according to spec. (intake .003 to .005 in, exhaust .005 to .007 in). Tried to turn over before I put plug in and no problem. Put plug in and back to square one. Tries to crank but stops after about 1/4 turn of engine. Not a mechanic but literate. Help or ideas please. Thanx.

 

[bertsmobile1]

:welcome:

pull the rocker cover off and watch the valves.
The inlet should close at the bottom of the stroke then just before TDC it should open a tiny amount to decompress the engine.
If that is not happening double check the valve lash and repeat.
If you are dead sure no decompression is happening then it is a new cam time.

 

[mechanic mark]

Did you adjust valves on proper stroke, both valves closed & 1/4" past top dead center?

 

[Rivets]

Pull the dipstick and see if the crankcase is overfilled.