OS 4 Stroke Cam Timming ?
I found it about a third of the way down
How do I set the timing on my OS single cylinder engine?
We recommend you send your engine in for service rather than attempting to set the timing yourself.
However, if you're REALLY comfortable working on engines, these steps will allow you to set the timing. If you are unsure how to complete any one of these steps, we caution you against disassembling your engine and recommend instead that you send it to our warranty and service center for non-warranty repair.
The proper way to set the timing in all O.S. single-cylinder engines with the front camshaft is:
Rotate engine so that the piston is at Top Dead Center.
Locate the timing mark on the side of the cam gear.
Insert the cam gear so that the timing mark is in a direct line with the center of the cam followers and the centerline of the pushrods. It is NOT at a 90 degree angle to the crankshaft. The angle will be slightly back.
Replace the cam cover and you're ready to go!
This should get your engine running well, if the timing was off. If it is still running poorly, be sure to send it in for service to avoid accidentally doing more damage.