Forum

[John Turner]

Upto the mid 90's they used 5/16" cycle which is 26tpi. After this they changed to M8 x 1.0. The difference is very little 26 threads per inch compared to 25.4 threads per inch and a diameter of 0.312" compared to 0.315". A normal M8 x1.0 nut will probably fit both rods but on a longer nut like the brake rod adjusting nut the thread will bind if you get it wrong.
JT

[simon]

Timing cover on my bikes was secured with whitworth screws Norm. Agree though that it would have been wiser to go whit into the ally for the head studs although to be fair they are a long thread and I haven't had one strip yet, clearly though your experience is greater. The ones that did strip on the old bullet we the rocker mounting studs. I made stepped ones with 5/16 whit bottoms stepping to 1/4 cycle tops. A pig to fit but a much more reassuring feel when tightening the rocker blocks.