G80TCS Piston Information

[RogerNorman]

Bit of a plea for help - has anyone got an old piston catalogue with a Hepolite or similar part number for a standard bore piston for a Typhoon?
I know from the Red Book that the Bore Size is quoted at 3.5005 to 3.4995 and a standard piston is 8.7 CR (12.1 was available but my standard one hurts enough when it kicks back thanks!).
I am in discussions with Thorntons to source a standard piston but between us, have run in to problems sorting the right piston.

[Don Madden]

Info on these is sparse, even the spares list is a typewritten sheet, probably prepared by Cooper Motors, the USA importer.

You keep saying "Typhoon" but there were two versions, the 1959 only & 1960-62. The 1959 cylinder, head, & piston differ from the later & the parts do not interchange except as a complete set. Better make clear which you need. Cheers, Don.

[RogerNorman]

Sorry Don - yes should have known better . I have copies of just about every bit of Factory information that I think existed and yes your right - '59 were quite a bit different.
Mine is a 1960. Thorntons are now telling me that aftermarket pistons were never made for them - seems strange as mine is clearly running with a replacement but then maybe a special was made - that's what Thorntons have suggested as an option.

[Don Madden]

I have seen Venolia pistons for both 1959 & later. They probably still make them but they have a reputation for high expansion, requiring a loose fit. I will call some of my contacts. Is it the std. size you are looking for? Cheers, Don.

[RogerNorman]

Thanks Don Yes ideally standard.
I am going to have to get the barrel bored and re-sleeved (which in itself is a challenge on an Alfin Barrel as I'm sure you know). But at least with a standard piston I have got somewhere to start.