Hello
This is a question which has been asked before but don't quite understand.
I assume I need a later low compression piston 7.4:1?
I have some Goldie touring cams, how thick should the compression plate be 2 or 3mm?
Will it need to be timed differently?
I assume the carb will need different jets?
Do people run a concentric carb if so which one?
Thank you
Matthew
I am confused.com. T140? my T140 is a 750cc Triumph Tiger. if you need a piston I hove two new ones in my garage.
My recently purchased B31 has been bored and a Triumph piston fitted, is it from a T140?
Bunners
I believe that the T140 piston (76mm bore) has the same gudgeon pin size and when the B31 cylinder is taken out to size a 2mm compression plate (ideally aluminium alloy) gives a compression ratio between 7 and 8:1
I believe that a BSA B44 piston of 79mm will also fit with adequate meat on the barrel and give you a capacity of 431ccs and would need a similar (or even 3mm) compression plate to get under 8:1, bearing in mind you will need a paper gasket +/- a smear of gasket compound.
I tink that a 626 or 628 concentric would be ok to match the head, I understand from another contributor (Andy Higham) that Roy Shearwood does good gasflow and valve work for these projects.
To make the most of this work you will need some new cams and I have heard that a pair of repro 2446 scrambles cams can work really well in these (I ran a pair in my B33 for a while) but with 6.5:1 CR and road silencer they were only ok.
Ignition timing will be an experiment but 7/16" BTDC will be a good starting point