My 1961 B40 runs great until around 20-25 miles then starts to hesitate at large throttle openings then it cuts out completely and will not restart. I have sparks and plenty of fuel but it will not fire back up. Leave it for a couple of hours and it starts straight away. It suggests an electrical component overheating and when it cools it is ok again, but before it cuts out completely it appears to be a fuel issue missing and backfiring at bigger throttle openings. I have set the valve clearances larger in case they were holding a valve slightly open but there is still good compression when hot.  Any ideas???
Ian

Hello,
the reccomended oil for my B40 is SAE 30 according to the manuals. Are modern multigrade oils suitable and if so what grade?
Ian.

Hello,
I need a kick start shaft with bush for my 1961 B40 distributor engine. Is it the same as a C15 one?
Has anyone got one for sale?
Ian

Hello,
This is my first classic british bike. I have had bikes continuously since the age of 12 mainly japanese and Hinkley Triumphs.
Ian

Good afternoon,
I am trying to find out the AC and DC terminals on the old style rectifier fitted to my 1961 B40.
Has anyone got a photo of theirs please.
Ian

Hello,
I have just bought my first old british bike. I have had dozens of jap machines and also hinkley triumphs, all metric threads. What screw threads are used on my B40. I presume they will be BSF.
Thanks Ian.