fork oil fo /5

[yappo]

i'm about to install a set of progressive springs.what weight oil?they also say the amount of oil should be 51/2" from top without spring in place and fork in collapsed position.should i get specific oil for forks or what?regards,brian.

[20774]

Yes, you should get oil that is recommended for forks. There are substitutes, but best to use the "right tool for the job". I'd say use 7.5wt oil...that's what BMW recommends. However, it's a personal thing and people do a lot of experimenting...different weights, more or less volume, internals spaces to compress the springs...

I've never done the measurement from the top thing...I just fill with the recommended amount. For /5/6/7 up to 1980, the later recommendation was 250cc after a complete rebuild; 235cc if it's just a drain and refill.

Start with something and see if it works for you. If not, change things around...

[tommcgee]

Yeah, get fork oil. Any motorcycle dealer carries it. If you thought the old springs were too soft, in addition to the progressive rate springs, go for some heavier oil than the OEM recommendation. 10W is common, or mix a quart of 10W and 15W to get 12.5W.

Personally, I'd rather have heavier straight rate springs but have had trouble finding any off the shelf for a K75. For now, I'm going to use the progressive rate springs and send an old spring to Sonic Springs in Oklahoma to see what he can do for me. The 1Kg/mm straight rate fork springs transformed my Vstrom and the K75 needs the same treatment.

[yappo]

your info about fork oil was just what i needed.best regards,brian.