Making And Using A Degree Wheel

Making a degree whell is actually very easy. You can find printable degree wheels online. They can be printed out and stuck to a CD, cardboard, or whatever you like. I find it easiest to print on sticker paper, available at lots of office supply stores pretty cheap.

I started by putting a piston stop on my cylinder. If you don't have one, they're very easy to make. I just cut mine out of some flat bar I had around and drilled 2 holes for the cylinder studs to pass through. If your piston doesn't reach the top of the cylinder you'll need to drill a hole in the center so you can put a bolt through with a nut or by threading your piston stop. Otherwise the piston won't hit the stop and the stop does you no good. You also need to secure the cylinder so it won't move while you're working.

I removed the side cover, fan, and flywheel earlier so I just used the flywheel nut and a large washer to attach the wheel to the crankshaft. I had to use some washers behind the wheel to get enough clearance from the engine case. You'll want to keep the wheel just a little loose for now.

As you can see here, I used a paper clip bent and bolted to a muffler mount location as a timing pointer. You can use whatever works for you in whatever location you desire.

Then I rotated the crankshaft clockwise until the piston touched the piston stop. You only want to use gentle pressure, don't try to force the piston farther than just touching the stop. I made a note of the reading on the degree wheel. I then turned the crankshaft counter-clockwise until the piston was once again at the stop and made a note of the reading on the degree wheel. TDC is exactly in the middle of the 2 readings. Adjust the degree wheel accordingly. If properly adjusted, the piston should stop at the same reading on each side of 0/360 degrees. In my case, it was 345 degrees ATDC and 345 degrees BTDC. Once you get it dialed in, tighten the degree wheel so it doesn't move. Go through the steps again and make sure you haven't thrown anything out of adjustment when tightening the wheel. If it is only slightly off you may be able to bend/reposition your timing pointer instead of the wheel itself.

Once everything is secure, the piston stop can be removed and the engine can be rotated to 0/360 degrees (TDC).

You can measure the piston's height above or below the deck at this point. I didn't do that right now, just looking for exhaust port info at the moment.

I rotated the crankshaft clockwise until the exhaust port was just about to open. I made a note of the reading on the degree wheel.

I then rotated the crankshaft clockwise until the piston had just covered the exhaust port again and made a note of that reading. Continue to rotate the crankshaft and note the timing of any port events.