As per heading I,m looking for a set of piston rings for my HM21 85mm type +030 or +040, Can use B33 rings for oil ring but compression rings would mean modifying piston.If anyone has a set please let me know. thanks DAVE.

Hi Dave...try.. www.vintagemotorcyclepistons.co.uk and www.pistonringshop.co.uk ...Ian

email (option): ian@wright52.plus.com

Hi Dave Gaggs of Nottingham 0115 9786288 have got shed loads of NOS rings and ring sets. Worth a phone call.
Cheers, Mick.

email (option): mick@motorbikemike.org.uk

Hi, Ian tried www.vintagepistons.co.uk no luck there also ringshop have stopped trading at moment?.Mick tried Gaggs they dont sell spares anymore,only speedos,magnetos they have sold there stock to john phelan Dave

Bantam John it is then. He must have the biggest stock of pistons in the country by now. Ron

email (option): ronpier@talk21.com

Hi,Rick I have a watch on these as I always buy old stock parts for all my bikes if the price is right,These will fit a 85MM M21 but you have to machine the piston ring groves to fit the compression rings,this is something I try to avoid if possible in case of possible fracture of piston.I have also tried goldie top rings as these are a thinner ring than b33 but to no avail.Something will turn up just have to wait Dave.

Try Googling 'Cox and Turner'..they are in Dorset and very helpful in finding odd rings/pistons. I don't have the number to hand but if they are not on the internet I know Ron Pier has it...Ian

email (option): ian@wright52.plus.com

Yep. John Turner 01425 652627. His son Ian, and partner Martin Turner run the machine shop. But John is the piston man. He's a lovely old guy who live in Alderholt nr Fordingbridge. Ron

email (option): ronpier@talk21.com

hi dave ,what is the measured thickness difference?or is it the inside diameter?if the rings are too thick cant they be surface ground to the right dimension, cheers rick

email (option): richardholt@rocketmail.com

Rick the B33/M33 rings are to thick also to deep,if the depth was ok I have a mate with a magnetic surface plate who could then grind them to suit,but then the piston would need machining to get the depth.I am now looking at ARIEL VB600 rings these look promising Dave

hi dave,me again ,just recieved my old bike mart ,try J Phelan ,stocks 9500 pistons + rings + liners , sheffield 01246 476888 cheers rick

email (option): richardholt@rocketmail.com

hi dave, how did you get on with your rings ?did you get fixed up,if you did will you please measure them before you fit them for future reference cheers rick

email (option): richardholt@rocketmail.com

Rick, Jason @ F W THORNTONS are sending a set for me to try.They dont list these as a set but if you know the right people they will sell them from size of piston/bore just like HEPOLITE used to in there ring cabinets sent out to local stockists.Will post back once I have them for future reference just in case someone else needs a set Dave..

Sorted Rings arrived & are good fit.The compression rings are 1.56mm in width & oil ring is 3.93mm in width both are 3.35mm in depth.Have also fitted one piece valve guides,new mains,rebuilt oil pump... Just a case of bolting it all back together a days work and she,ll be running Dave...