If this has been proposed before, I am sorry!
It concerns the old problem of the front engine bolt on Flyer / Rep type frames crushing and distorting the case.
It tends to alter the main bearing end float and if the original 26TPI fine threads are used with too much enthusiam, the bosses can break.
Tap the front engine bolt hole to accept 16mm helicoil and fit helicoil.
Use a 16mm hex head bolt through the frame and bolt the frame to the engine each side.
The frame is flexible, so will not distort the case.
The case will be held rigidly and not “chatter” in its fixings, thus smoother engine.
Kind Regards to all
Roger : A very interesting suggestion. Is it superior to your previously published solution of a 5/8″ diameter steel tube bonded into the crankcase front mounting holes? It would be lighter of course, but possibly not as rigid. Regards, Mike Fennell
I can not understand why I did not think of it before!
It is lighter, stronger and more rigid.
It will prevent boss breakages and crancase crushing.
If a locking insert is used, there is no chance if shaking loose.
A 16mm bolt measures about 0.624″ so is almost the same as a 5/8″ bolt
I will stump up the cash for the tooling and try it out as I quoted some customers for fitting a tube in the crankcase front engine mount holes to withstand crushing.
I can not do that now I know that this is much better.
I will let you know how I get on