Any spacers on the timing side are optional ones to shim the crank. The drive side has a distance collar of specified thickness plus optional shims. The original system was similar to modern cam shims in that one shim was exchanged for another of a different size rather than adding numerous thin ...

No previous record for these numbers in the club's register, no surprise there if it has been abandoned for a long time. Try again with the frame number, I suspect it is 1990, you may have to remove some paint, which you will have to do when the bike is inspected for registration. Even if you can ...

Guides should be honed to the nominal size as the clearance is on the valve.

For details see the excellent series of articles written by Jerry Mortimore in the Cheval de Fer (Ariel club magazine) between September 1993 and February 1994. All available on the club's website.

Looks like a 6 to me and we don't have a record of PFR 505

PFR 506 has one entry in the club's register from 1990 when it was owned by long time club member Neil Stewart from Kineller near Aberdeen. It was a 1958 FHS ie Huntmaster Sports. As Simon says, DVLA list it with 1000cc engine, which probably means that the frame has been modified to build a s/arm ...

That loom is for a 1951-58 SQ4 so is correct for your bike. The PB suffix denotes a plastic tape bound one rather than a cloth bound one that Draganfly supply. Theirs come with a diagram for use with the loom, the manufacturer and other suppliers don't bother making one. I have sent you a copy by ...

I would ditch the oil cooler so that your engine will be less likely to overheat and your oil stands a chance of reaching working temperature. The engines tend to run too hot whereas the oil does not become hot enough. Cooling cool oil will not cool the engine!

ooops, no it it doesn't, not introduced until the following year.

No, there isn't one. Just reasonably tight, say 20-25 ft/lbs. Other views will be available!