Quote Originally Posted by look no hands View Post
Hi all,

I'm thinking of doing some piston tinkering, now a few questions to the tuners amongst us

If you can get a decent mirror polished saddle/area on the rear of the piston, is it really worth buttoning the piston for smoothness?

Is it actually worth buttoning the piston, does it really make that much difference?

What is the best weight for a piston?

What is the best way of lightning a heavy piston, machine off a bit of the girth in the middle or drill holes?

As for seal sizing, what's the best way and what's the sliding fit supposed to be like, should it glide down under it's own weight or a gentle push from your finger?

Thanks for any advice.

Pete
Hello Beesa Pete.

Buttoning (or Delrin ring):- Would always have to be seen as a good idea to reduce metal to metal contact. However, on reassembly, I always grease the rear of the skirt. Then, once the piston is pushed fully forwards I always smear some more moly grease on the inside circumference of the cylinder, behind the piston. Recommended by Steve Pope in his fitting kit instructions so it has to be good advice and it's always worked for me. Using synthetic bearings would reduce the amount of lubrication required in this vital area.

Best weight for the piston? Blimey, that's a BIG question and the answer very much depends on the individual gun, bore and stroke dimensions, transfer port size, preload, spring force and even the pellet used.

In terms of seal fit, I'd prefer to go for a "push fit" rather than the piston dropping under its own weight thinking, but it does seem to be down to personal preference.

Sorry it's all sounding a little of a cop-out, but like so many aspects of springer tuning, much of it is down to the individual.