timing

[tlbranth]

we have a 4 year old Craftsman mower with a Briggs 123M02-0345-F1 engine. Ran fine 'til yesterday. Now it starts, reluctantly, but sounds awful - like the timing's off. How do I check it? Is there a sheer pin in case something big is struck? I had a mower once where that happened and altered the timing.
I'd really like to get a repair manual. Anyone know where I can get one?

 

[Scrubcadet10]

Remove the flywheel nut, there is a keyway cut into the flywheel, it should line up to make a perfect square. If the key is sheared it will throw ignition timing off.
You can type in that model number in at Jacks small engines, and scroll down to the bottom of The parts lost and you can buy a repair manual.
Or type in your model # into Google and put repair manual after it.

 

[Romore]

The key should not be sheared unless you struck a solid object with the blade. The repair manual is B&S p/n 270962, there are also generic manuals available. Try your local library.

 

[Rivets]

This manual should help. https://docs.google.com/open?id=0B6NaqjIxWV1ycG8wd0s3Z2Q2X00