81mm pistons

Hi

Is there a piston bigger than a 81mm suitable for racing? Does a bigger piston actually fit ie 920?
Found out from Dave that my JE pistons came from Sreve Maney, the only ones he does not show a plus 1mm oversize for.
Barrels off to someone who knows what they are talking about, so hopefully will have some news soon.

Chris

Hi Chris,

the only larger size available in the JE pistons Steve sells are the 83 mm ones for his 1007 kit. We've never had a call for oversizes in the 81 mm bore design, so I've never had any made. JE would be happy to make them, as long as I order a minimum of 4 pistons. I normally order pistons in lots of 16 or 32, so an order of 4 would be a bit more expensive. JE has been turning around orders pretty quickly lately, so it would be a matter of weeks, not months. Let me know if you would like to do a special order (minimum 4), and I'll get a quote for you. I'd have to check with them to see what sizes they can do. I assume you'd like the minimum, maybe +.010" if possible.

Otherwise, both RGM and Norvil used to sell oversizes, up to 81.5 mm if I recall correctly. They were cast, not forged, but I used them in race bikes with no problem. RGM still sells them in 81 mm +.020", and they are now standard pin size, as opposed the old ones that required honing the rods out for a larger pin.

Ken

Hi Ken

Thanks once again.

Steve has e mailed me & suggested relining the barrels. I am having someone look at the barrel for me soon, so hopefully I will have an idea if they can be saved. The pistons have been lightened/modified underneath & there are no reference numbers blank or ref.
Rgm option is intresting & gives me a chance. Things are tight at the moment. I will be out on the 750 by the end of June, Donnington being the one I really want to do. I will contact you once I have some news.

Thank you once again for your kind offer & help & advice.

All the best Chris