fork oil

[Dale Sonnenschein]

I got my forks together last night on my 75 250 penton. What weight oil should I use and how much? Or should I go by the manual? I have the ribbed ceriani's. I'm in the northeast and plan on riding CC and MX.

74 puch 175 SD
73 Husky 360 WR/RT
75 Penton 250
10 ktm 250xc
02 bmw r1150r

[chicagojerry]

here's what i do on my personal race bike and i race both cc and mx. forks out of triple trees, verticle. springs out,  fork compressed. fluid six inches from the top of the upper tube edge. i usually just use a couple of tie wraps measured out to six inches.  the wt fork fluid that i use is 15 wt.  thats in "suspension/fork fluid" weight.. remember to exercise the forks to work all the air out before your final measurement.  chi jer

[Dale Sonnenschein]

I seem to remember the 6 inch thing from years ago. I wasn't sure about it though. Thanks jerry

74 puch 175 SD
73 Husky 360 WR/RT
75 Penton 250
10 ktm 250xc
02 bmw r1150r

[tomale]

Dale, Jerry is right, at least that is a good place to start. Here is the thing, asking how to set up your suspension is like asking which pair of shoes do I need to wear. That is a personal thing. What works for me or jerry may not be a perfect fit for you.  For many years I used ATF in all of my forks but last year I started using 10 wt oil and adding a bit more fluid in each fork leg.. Here is why I did it, I found that the forks were a bit stiff in mid stroke and I wanted the front wheel to track a little better. but  this caused a problem. All of a sudden my fork springs felt too soft and they wanted to bottom out. I solved it by adding schader valves to the fork caps and adding a little more oil in each leg until the forks no longer bottomed so often. What I would recommend is to do what Jerry says and then play with it until you get what you want. you can add air to the forks but I don't think it is a good idea. it tends to make the forks too stiff at the beginning of the stroke and that will tend to make your front wheel lose traction.


Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki

[Dale Sonnenschein]

THanks Tom. I really needed a place to start as your right about each persons preference of feel. Who ever owned this bike before me had some sort of air valves in the caps ( actually in 1 cap??).In the early 80's I ran air in my forks but it was minimal, like 5 lbs or so. But that was MX only. I know that adding some oil will help stop bottoming out. On my modern bike I like my suspension a little soft. So maybe I should start with a lighter oil?

74 puch 175 SD
73 Husky 360 WR/RT
75 Penton 250
10 ktm 250xc
02 bmw r1150r

[tomale]

That's great, good luck on getting it sorted out.. I believe the difference between a fast rider and a slow one is in the details. A fast rider knows that there is no such thing as "good enough"

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki

[brian kirby]

I set all my forks just like Jerry but I use ATF which is a little lighter than 15wt, but I weigh less too. ATF or 15w 6" from the top will get you in the ballpark then adjust from there. You can run as much as 5" from the top if you want more bottoming resistance (less air volume=more bottoming resistance). I prefer not to run any air, if you have the proper spring rate and oil weight/level additional air is not needed.

Brian

[dirtbike]

I also use ATF but I think my fork is a little underdamped. It doesn't bottom and seem alright but it feels to lively. I have heard others claim that 20wt fork oil is better. So that was what I was planning to use.

[dirtbike]

brian kirby, I have noticed that the seals seem to seal and last longer when there is some air in the fork. It seem to help keeping the dirt out and the seal lip tighter around the tube.

Does anybody have the same experience, or am I imagining things?

[Tim Brown]

Depends upon rider weight and ability. I weigh 215 and like 20 wt. at
5 1/2 down and a bunch of preload on the springs. My dad weighs the same, but at 70 years young likes 10 weight.

[tomale]

I weigh in at 250  and I use 10 wt. in my maico's and 6 inches from the top with no preload. For the Mc5 I am still using ATF, a 1/2 inch of preload and 6 inches from the top. I do not use air in any of my forks but they do have air caps so that I can make use of the Hydralic benifits of more oil in the forks. If your caps are vented then no amount of oil will change how often the forks will bottom.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki