fork revisited

[tomale]

Ok, I feel silly. I discovered the noise or what ever that was.... I had not checked my fork oil. the left side had no oil in it at all. I saw no signs of leakage. I guess I must have had a senior moment. I think I will blame it on the gray hair. Or maybe too many get off's when I was young. I went to look for the right oil and weight and amount and discovered that the only manual that I have are for earlier bikes. It does not cover my 76 MC5 250 I have tried to get on the other site but I have been unable to get the membership thing to work for me. Any one know what is the right amount for my Marzokes? Over the years there is the debate about what to use. What would be better than ATF in the forks I am a big guy and it would probably be a good idea to have a bit more dampening than what ATF provides.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[Rick/calif]

Thom, I own a variety of vintage bikes with betors, marzochis, honda,husky, etc. forks. To make it easy on myself I use the oil height method with name-brand fork oil, say 15wt. for starters, at 6-61/2 inches of air gap from the top with the springs removed and the forks collapsed. This way the level is always even between the two tubes and can be checked between rides should a slight leak appear. A suction tool is easy to make with a squeese bulb and clear tubing. Good luck.

 

[tomale]

Thanks Rick,
I put some ATF it and it was too soft of dapening I thought. I will try the 15wt and the measuring idea, thanks.
ATF may not be the best but it is better than nothing and I will change the oil before I take it out on the trail again. Besides putting ATF will work like a rinse so that what ever maybe in there will be more likely to come out when I change it out for better oil. No use wasteing the good stuff. I use to use ATF on my Buls and Montesa's but that was long ago and I was alot lighter of a rider then.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[tomale]

I do want to try what rick suggested but does anybody know what the factory suggests is the right amount of fork oil? I would like to try Ricks suggestion and then check it against the factory specs. I am sure what Rick suggested will work but I like to be sure. I know I am strange.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[john durrill]

Thom,
 if they are 35 mm forks  , we used 190 cc
( the book says 185 to 200 cc in each leg)
 we pulled the springs , let the bike rest on the floor with forks compressed. then measured down from the top of the tube to see which leg had the lowest oil level.  added oil to that leg to get the same oil height in each leg. it works great. we went with 7 and 1/2 weight oil for our use . the forks are very smooth over their entire travel. its the height in each leg being equal that makes the difference i think.
 we had 3/8 of an inch difference between the legs. first time i ever did it by measuring the height of the oil. Man was i missing a good thing all those years
John D.

 

[JNOYES]

The specs I have for a '76 with Marzocchi's indicates 260 cc per leg.  This is the spec sheet from Al Buener.

Jon

 

[john durrill]

We are running 75 0r 74 35mm . i think they only have 7.2 or so inches of travel.
 thats why we were using the 185 t0 200 cc's of oil. thats specs for our forks

 

[DKWRACER]

For 35mm M-zokes, have had good results with the oil height at 5 to 5.5 in.
Tom...

 

[Blue_Dog]

John:
Are you running rib forks?
B-D

 

[john durrill]

No B_D just a stock set of 35's off a 250 , a 74 i think Larry said when he sold them to me.
 Why? Something i need to know about them?
  John The curious :>P



Edited by - john durrill on 03/17/2003  10:24:49 PM

[Blue_Dog]

John:
Just wondering about a comment Larry made about the 75 mod forks as being over 7" in travel. I emailed him about the comment and a spacer he mentioned.
My concern was legality with ARMHA sportsman 250 class and a like-design 75 DOM bike. As I interpret the "Like-design" rule, if needed changes are made to the 75 to fall within guidelines any bike would be legal.(as noted one exception 1975 Maicos)


 

[john durrill]

B_D we took the springs out and bottomed the forks. they bottom out right at 7.5 inches with no springs.
 We were told knock off about 1/2 inch and thats the travel your forks have. guess you could do the same with any forks . If you had to add a spacer to limit travel, add the spacer length to the 1/2 inch and that would be what you have for travel.
 from pulling them down on a trailer with the tiedowns it looks like its a good rule of thumb.
 John

 

[tomale]

thanks everyone for the imput.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.