JP or GPM pistons?

GSAX1 · Post by **GSAX1** » Tue Jun 07, 2011 11:53 am

Wich one is better, JP or GPM? Or are they bad both?

Are there alternatives to these?

Michael

g80csp11 · Post by **g80csp11** » Tue Jun 07, 2011 8:14 pm

Given the choice, go for GPM
I wouldn't put JP pistons in any of my engines. usually much heavier and require large clearance to prevent picking up. I'm sure others will disagree

dogwheel · Post by **dogwheel** » Wed Jun 08, 2011 11:02 am

I recently exchanged emails with a most highly regarded, UK based, Motorcycle Engineering Firm, regarding the possibility of them reboring or re-lining the cylinder of my non-AMC British bike. I received a very helpful and encourageing reply, which concluded with "but no Aussie JP Pistons please". Sad and worrying isn't it!
You might think that the technical knowhow of such firms as Hepolite, Wellworthy and of course AMC has been lost, or just maybe there is a wonderful commercial opportunity here for someone to supply the needs of those of us who enjoy wearing out old motorbikes.

GSAX1 · Post by **GSAX1** » Wed Jun 08, 2011 11:11 am

Thanks for the input both. I'll go for GPM then.

Or are there alternatives? Surely there must be a piston that fits among those hundreds of thousands different types that have been made? A modern jap bike piston would be perfect.

Michael