75cc forks and dampers - how much Oil?

[chris78jota]

I suspect that there might be a limited pool of experience on this topic ??? compared to Jota-related threads, but I'm constantly amazed by the knowledge on the forum so here goes!

I've managed to get the rebuilt (hardchromed, new seals and bushes) forks back on my 1954 75cc Sport (a bit more like DIY than mechanicking compared to the Cerianis on my Jota) and they are beckoning for oil. Anyone know how much oil, and what type, to put in?

I've also been rash enough to try to rebuild the original rear shocks (only kept them bcause they are so cute if I'm honest), again re-hardchromed rods, new seals. They are ready to re-assemble, but this time I really haven't a scooby doo :-[ what type of oil, how much or even how to get it in without creating a mess.

Chris

 

[sfcpiet]

Chris,

Try 10W fork oil, fill the damper body about 3/4, insert the damper innards and push them down as far as they will go while allowing you to top up if necessary.  Keep the damper rod bottomed when buttoning up, excess oil will be forced out past the thread.  Trick is to exclude as much air as possible from the inside to achieve smooth damper action.  If too much air remains in the damper, action will be inconsistent towards the end of the rebound stroke

Of course this is quite messy.  You could open the damper once again and measure the oil volume, the 2nd. damper is then a lot easier and a lot less messy...

Sorry, no idea of the volume for the forks.  I'd just start off with a set volume and work my way from there.  My 100 is still on the work bench, so I haven't had a chance yet to fill/check the forks.

piet

 

[chris78jota]

Cheers Piet,
thats a good starter thanks.  The damper rods are hollow, and to stop oil leaking out of them past the screw-on top mounts, I have (stupidly I realise now) blocked the top of them up with araldite.

I think I'm better UNblocking them, and letting the oil come out of the top - that way it hopefully indicates a "full" damper.

Chris

 

[sfcpiet]

 The damper rods are hollow, and to stop oil leaking out of them past the screw-on top mounts, I have (stupidly I realise now) blocked the top of them up with araldite.

That's good to know, Chris.  Thanks for the pointer.  Will make the filling process easier!

My shocks were dry and still worked well, seemed like a bummer to open so I just did a cosmetic job of them.  Turned out nice with re-chromed spring shrouds.

Forks were a different story, not sure if I'll ever get them working decently.  Bike must have suffered a frontal hit, stanchions were bent, yokes buckled, and to top that, one spring was broken.  Got it all sorted, I hope...

piet