NOS Betor fork prep

[Ftwelder]

I got a crusty on the outside, perfect on the inside NOS Betor fork locally was originally built for a Rokon dirt bike from the mid 70's.  It looks like a cast version of a Ceriani GP.  Anyway, the bore of the stanchion looks worse than the a typical DOM tube and the pistons don't have non-metallic rings.  I am thinking I should hone the bores and add micarta bearings to the piston?  The main slider bearings are perfect, zero play. The springs are 495 and wire 3.95 which should be good for a BSA single?  I appreciate any advice. 

For reference. 

 

Untitled by barnstormerbikes, on Flickr

 

Untitled by barnstormerbikes, on Flickr

 

 

Untitled by barnstormerbikes, on Flickr

[feetupfun]

To work out the spring rate the coil diameter and number of active coils are also required. If they were well sized at the time for the ROKON they will be in the ballpark for rate for that bike for trials.

If the pistons aren't worn and you tidy up the tube bores without losing metal then you don't need to put rings on the pistons. I've got a few Spanish bikes with Betors that look like yours inside with not a huge number of hours and those forks work brilliantly. It's only worn tube bores and pistons that benefit noticeably from having rings. But if it makes you feel good, do it!

Teflon sheet cut into a strip works well for rings. I don't know what micarta is.

[Ftwelder]

On 4/16/2020 at 7:56 PM, feetupfun said:

To work out the spring rate the coil diameter and number of active coils are also required. If they were well sized at the time for the ROKON they will be in the ballpark for rate for that bike for trials.

If the pistons aren't worn and you tidy up the tube bores without losing metal then you don't need to put rings on the pistons. I've got a few Spanish bikes with Betors that look like yours inside with not a huge number of hours and those forks work brilliantly. It's only worn tube bores and pistons that benefit noticeably from having rings. But if it makes you feel good, do it!be good ion

Teflon sheet cut into a strip works well for rings. I don't know what micarta is.

Thanks!  It Ill likely just clean up the tube bores and call it done.  

Micarta is a early composite material made of various industrial fibers like wood, glass and canvas mixed with resins. It would be good (and cheap) as a piston ring running low speed in an oil bath, 

cheers,