This is my B31 which I have been racing here in Perth for about 5 years now, though I only get to about 3 or 4 meetings a year. Sometimes less.
It is essentially standard with a few upgraded parts, carefully assembled and has been pretty reliable.
Happy to pass on any info to help another "Iron Head" racer.
I went with 18in flanged Excel rims and use Avon tyres, they are excellent.
The cases are 1958 B31, thick flange, alternator type,
Standard Crank, with Gold Star big end, I don't believe an expensive aftermarket crank is necessary for a 350.
Standard Rod, crack tested and shot peened,
650 Triumph piston, ( same bore size as B31 ), I was using standard cast ones ( cheap ), but this year I have gone to a forged one from MAP, they are the business.
I replace the piston every 1-2 years, depending on how much use it has had, BUT, I replace the Gudgeon every season, as they are only 15mm dia and have broken 1, with disastrous results.
Biggest inlet valve I could get in,
Modern style springs to prevent coil bind,
, running on Methanol
With the cast pistons I was using around 10.5: 1 compression, which was fine with the Methanol and nice and safe for starting out.
This year with forged piston, I have gone up to 12:1
Anything else I can help with, just ask,
I took up racing at 45 years, and it is the best and most exciting fun I have had, I just love it.