Fork action question

[Bison]

Hello folks.
My 1978 3 1/2 Sport rides quite harshly on the front end, when I brake though the forks compress as they should. I think the problem may be stiction, although I've gone to great lengths to assemble the forks to minimise that. My question is am I expecting too much in the way of ride compliance?. My Laverda has a similar feel, IE it seems to just bounce over bumps and road imperfections in a straight line, but handling and braking are fine, well, for a Jota that is!.
I'm using 10W fork oil and the springs are original stock items.
Thanks,
Alan.

[EVguru]

Welcome to the world of damper rod forks.

This explains the underlying problem http://racetech.com/html_files/DampingRodForks.HTML

The rebound check valves leak badly and 10W means almost nothing. One 5 weight oil can be thinner (less viscous) than another brands 10 weight. Any decent fork oil will have a datasheet available telling you what the actual viscocity range is in centistrokes.

[Bison]

Thanks for that Paul, what an interesting article. Unfortunately no Emulators listed for our bikes. Did you ever get them working on your valentini project?, care to divulge which ones you used?, bearing in mind I have a lovely machine shop at my work!. Sounds to me it would be a worthwhile modification.
Alan.

[unreal]

This may not be your problem but I was experiencing undue stiction and final pinned it down to the fender bridge (which was a replacement stainless one from NML). After a bit of extra bending to get a perfect loose fit it felt a lot better.
I first found this by slackening the bolts and trying it around the block.

Simon