Fork sag

[Crusty Snippets]

I just replace the fork seals on Yami. Adjusted the steering head bearings as well. With the front end lifted off the ground I measured from the top of the rubber boot / cap to the bottom of the lower triple tree. Then I removed the jack and measure again. The forks sagged about an inch, but extended when I added air. Is this comparable to other bikes?

Was looking for the article here on front fork mods, but could not find it.
My current thinking is the springs have gone soft from carrying the weight of Yami since 1979.

Unkle Crusty

[motoman]

I just replace the fork seals on Yami. Adjusted the steering head bearings as well. With the front end lifted off the ground I measured from the top of the rubber boot / cap to the bottom of the lower triple tree. Then I removed the jack and measure again. The forks sagged about an inch, but extended when I added air. Is this comparable to other bikes?

Was looking for the article here on front fork mods, but could not find it.
My current thinking is the springs have gone soft from carrying the weight of Yami since 1979.

Unkle Crusty

That's gonna be considered normal 'sag' . My fronts on the fully dressed Venturer drop bout half that distance, no air. But it also was the ONLY model that had factory installed progressive springs that were also slightly larger wire diameter. Larger wire diameter was also used on the rear KYB's on that model ONLY also. #2 spring pre-load setting with my 175lb.weight and all the necessary gear for a LD ride is all that's needed and still give a pleasant ride.

[mack]

Sag

Not sure what you mean by sag. If it's fork comprssion then measuring the springs in their relaxed length will tell you what you need to know. It's not all bad though. PVC spacers will make up the difference and the bike will handle the same a new.
However if the sag you refer to is at the upper and lower leg , along the length then the bushings are the culprit. The uppers are easy to replace but the lowers are a bit different but can be done.
I always check the play in the bushings before i reasemble the forks. Usually the uppers are worn but the lowers are still ok, but enduro style forks use the same config and arte interchangeable. if you need I can run down and exact match (or several) if you like.

[Crusty Snippets]

Sag

Mack.
It is spring compression that I mean.
I have a spare set of springs, and can measure all of them. They poke up about an inch at the top when the cap is removed. I will compare lengths and maybe consider spacers as you suggest.

Unkle Crusty

[jetmechmarty]

You're saying you have about 25 mm of sag with no load on the bike? It's on the sidestand or centerstand? Either way, that is a lot. I have 35 mm laden sag with me on the bike and no centerstand or sidestand.

From what you're saying, your bike probably sucks up bumps pretty good, but I expect cornering is terrible.

[mack]

Caps

It can be a bitch to get those caps on after the springs and spacers are in. A neat trick is to scribe a mark on the cap and tube where the thread starts to engage before you insert the springs. I use a big cresent wrench to push down while lining up the marks, then a quick turn under pressure will engage the threads. Since you have it apart anyway, it's a good time to replace the seals in the caps etc. They are 30 + years old too.