Probably wouldn’t need to be as long as 1” if it was only holding the chain guard to the frame. Does it hold the exhaust pipe bracket as well? I machined my ‘bolt’ from a piece of hexagon so that I could put a nut on each end - almost certainly ‘wrong’ .....
As an aside - I found that when the pipe got hot, it expanded pushing itself through the clip. Then when it cooled down, it contracted but the clip was tight enough to hold it - as a result the pipe pulled out of the cast iron manifold at the front. Expansion was about 3/16 - 1/4 inch. I made a slot in the tailpipe clip and a shouldered washer to fit through the slot to create a slip joint. This allowed the pipe to expand and contract without disturbing the joint at the manifold.
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my 1920 chainguard is a bit broken, anyone able to post piccies on how they should be joined, ie top bolts to a hole in the crankcase and to the frame towards the rear, assume the bottom attaches to the top, there's a rear point intact but front is a bit hacked about. pic is of bike, will post pics of guard in another post
