As Paul says the outer race (BALL bearing) kept in place by a circlip in the alloy does the locating of the crankshaft using the force of the spring in the cush drive. Nev

Check your gauge against another. Valve timing can affect pressure. Being even is good enough really. Nev

They will also make ones with alterations OR one off's. If I was getting one done I'd seriously consider eliminating the Hardened cap and having the end hardened. I have some valve adjusters with bigger radii and area on the contact end that have worked fine. That can't be applied to the 30 and earl...

It IS a bit mind numbing doing them individually but unless you are sure they are an original matched pair it's a "Do it once, do it right' thing. Check the Assembly when finished for reassurance. Flywheel run out will cause vibration. Nev

I think the original valves are both the same length and head diameter so you could use another exhaust one with the bigger diameter guide grooves and oil feed holed.. Nev

Yes true. I've at times tried to hold the armature where it gives the LEAST path. The general view with Mr Lucas seems to be to have a strong enough magnetiser and all will be well. .. Nev

IMHO, Shinier than new is not the way to go these days. A well patina ed "Original" will get more attentionif it's genuine and IF you are fortunate enough to find one Toffee Apple and milk bottle top resto's were popular 40 years ago. Lot's of extra chrome. I was roundly and very publicly ...

Well I've had trouble with Velo's flat rubber(neoprene) belt and I bought a Matchless that had a TOOTHED belt driving the MAGNETO instead of the original well oiled chain (For some reason that eludes me.) but it had worked for at least 3.000 miles. The C10 C11. BSA's run a very small chain Nev

I would have thought that any kind of Keeper would reduce the magnetic field strength left remaining to go through the armature. When you are magnetising with the armature in place, the armature diverts some of the magnetic flux from going through the Magnet. Nev

Mounting the horn at the front and having it forward facing means it is likely to vibrate at certain engine revs and that causes the bracket to crack prematurely, usually through one of the four smaller holes. It's caused by a harmonic not bad engine balance. A suitably located block of hard rubber ...