Attach a degree wheel to the rotor

Ok - so I have a piston stop and have found TDC accurately with it by bracketing. I'm happy with that, but now to find 28 deg BTDC, and the indicator dial inside the cover is missing. Ive ordered one, but would rather set the 28 deg mark by the dial - obviously there will be inaccuracy depending on the casting and how its attached. I need some way to fix the timing wheel to the rotor but Iit seems I will need a bolt to do so. What bolt diameter and what thread type? I work on the bike in a dead end street outside a storage unit where the bike is, so no joy with turning.threading etc - I need to buy a bolt or have some other solution which guarantees the disc is centred and stable.
Other options I have seen include magnets, bits of wood/dowell, double sided tape etc - but if not perfectly centred will give inaccurate degree readings, and I wonder if any options other than a bolt will be accurate. Norton owners ingenuity wanted - thanks all for your help

I've used blue tac with great success. Once you have the disc attached to the crank end you can easily make up a pointer with a piece of welding wire (or some other stiff wire that you hook under any handy bolt head) and bend that to wherever you need it to be so it lines up at TDC. Might sound crude but it's worked a treat on everthing from Commandos to Manx Nortons and Velocettes.

I have a degree disc made out of an old c.d. The hole in the middle will take a short piece of oil hose that fits perfectly in the end of the crank.

You don't need to fasten the wheel to the crank permanent like. I glued a golf tee to the center of my wheel and just pressed it into the crank. And just some stiff wire around a bolt or something and turn the wheel until you have it where you want it. I think there's a printable wheel in the first sticky thread.

Or you can do it the easy way.

Once you have a TDC mark then measure right along the inside edge of the stator _ .735 from for 30 degrees or .686 for 28 degrees and make a new mark.

Of course - brilliant - simple maths wins again. My bikes a train ride away so I cant check for a week - I trust the numbers given but can anyone tell me the internal diameter of the stator ? Doing the math will give me something to do that will make my wife shake her head.
Thanks

DrMike said:

Of course - brilliant - simple maths wins again. My bikes a train ride away so I cant check for a week - I trust the numbers given but can anyone tell me the internal diameter of the stator ? Doing the math will give me something to do that will make my wife shake her head.
Thanks

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Actually the numbers I gave you are from measurements taken after using a degree wheel. They are written on a note hanging on wall in my shop.

The rotor is roughly 3 inches though if you want to give your brain some exercise. The measurements are a straight line measurement not following the curve of the stator. Jim

Just FWIW - I attached a degree wheel by using a half inch rubber hub for the drum sander from my Dremel. I had to wrap a bit of vinyl tape around it, but I just ran a 6 X 32 screw through the center with some washers, cranked it down until it held steady and then used a couple more nuts to secure the degree wheel.

Russ

You can stick the degree wheel on there in any manner that works - I have used hot glue, tape, mastic, or, of course you can use the center bolt/nut. When I worked at engine building I used to have several fancy degree wheels from Competition Cams, Isky, and a couple others but now I just use a printed out wheel glued to a CD. Since there is no "strain" on the degree wheel at all, the attachment method is not particularly critical.

FWIW, when I degreed my 850 a couple of years ago when I installed new rings, I found that the factory mark was within 1/2 degree of actual TDC. I have heard all sorts of stories about how inaccurate the factory mark is but mine was essentially right on. 1/2 degree is about the width of the mark itself.

mike996 said:

FWIW, when I degreed my 850 a couple of years ago when I installed new rings, I found that the factory mark was within 1/2 degree of actual TDC. I have heard all sorts of stories about how inaccurate the factory mark is but mine was essentially right on. 1/2 degree is about the width of the mark itself.

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My primary cover has some room to move around on its pins. I found mine was right on if I shifted it forward and down in front as far as it would go. If I lifted up and pushed it back it was off a couple of degrees.

Russ