Mazda Rings (?)

[muskrat]

Would have to be 3mm (0.120) over 
Cheers

[chaterlea25]

Hi All,

Yeah, sadly that mob are still robbing older speedway/grass bikes for their japanese engines.

 cyclobutch,
You probably meant  J.A.P speedway engines ?
Built by the company founded by  John Alfred Prestwitch (London)

Serious  competition with "vintage" engines now means that most competitors use replica motors from companies like these
http://cameronracingengines.com/#home
and
http://www.eurospares.com/greg.html

John

[cyclobutch]

Yes of course - no idea how I screwed that, can't even blame that on autocorrect. Thanks.

[a10gf]

Yes of course - no idea how I screwed that

  You did not. It's a very old "Censored Words" setting on the forum, some thought that j a p was not respectful, so was set to change j a p into japanese. Spaces added to avoid the censor :O)
Sorry for the confusion.

[WozzA]

    Stupid censor ...   

[coater87]

I'm not sure of how the math is done, or what crank may have been used, but you could stroke and bore the engine to get pretty big CI numbers.