Ariel Owners Motorcycle Club

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S/H piston from Pete Collings now fitted, Hamlins agreed that the "slight scores" were nothing to worry about and that its a 6 thou clearance in the +30 rebore originallydone for the JP piston. They very kindly checked and gapped the set of Welworthy Matchless std. size piston rings and agreed they are Ok to use.
Barrel and piston are now fitted and just waiting for vales & guides. The JP piston I am urging Hamlins to send back as "unfit for purpose".
And so, many thanks to Pete for helping me out of a hole.

I think JP have been taken over by new people. I've seen their latest VH piston and it's very different from the early overweight ones. High(er) silicon does make the alloy heavier. Internally tapered gudgeon pins help reduce weight. I'm not overly fond of "T" slot pistons especially in performance engines or sidecar work where you will need more clearance to prevent nipping up. Running in doesn't take much metal off. Better to have the clearance to start with. It's along time to reach the wear limit for most of us. Nev

I'm pretty sure I saw somewhere (a little while ago) that JP were re-working the VH pistons in the light of the problems people were having with them.
It'll be nice to know how the new type(s) perform, and how to spot the differences between them so you can tell which type you've been supplied with!

SG

Did nobody tell them the gudgeon pin wont fit the small end bush? Or is that just a careless lack of quality cotrol in the revised production?
Yes, I could get the small end bus enlarged, but its not easy without detatching the rod, that's why, even if it is improved in other ways, I count it as "Unfit for purpose", That, and the weight.

It's not like you really have a great choice of suitable pistons. I'm fortunate to have enough Polson pistons left over from my older purchases and some are remachined "used" oversizes. . Never throw anything out that might be needed sometime. It's 65 years since the last Ariel VH was made. Nev