Marzocchi suspension help?

[Big Mac]

Anyone have details on the recommended amount of fork oil for 35mm Marzocchi forks on my '77 Penton/KTM?

How about oil level or rebuild tips for Marzocchi shocks on same bike? Appreciate any help from someone who's been down the road on dialing in old Zokes! thanks, Mac

[tomale]

Jon, and to others who might find this interesting,
I believe the amount of oil is 260cc's but that is only a place to start. once that it is in place double check it by removing the springs and compressing the fork until it hits the stop and then check  to see how high the oil comes up in the fork tube. You can use a wood dowl or any thing long and skinny enough to measure the differance between the height of the oil in the fork tube and the top of the fork tube where the cap screws in.
The reason this is important is because, as others have said there is a good chance that the actual capacity of each fork leg and tube could be and usually is different. IF the oil level does not come up to the same place in each fork leg the spring rate will not match. Part of the spring rate or rather the amount of pressure required to compress the fork is effected by the amount of oil, since part of that compression rate is aquired by the compressing of the air in each fork leg. The more that these are off the more the it will effect the compression rate the more it is compressed. It might seem minimal when the forks are at full extension but becomes much more significance the more they are compressed. The compression of air is progressive in nature. this is why Air shocks work the way they do and why they seemed so stiff even when you were sitting on the bike. They had almost no sag rate because it required so much air so that they would not bottom out under a heavy load such as landing off that double.
The other day I rebuilt my sons XR200R forks and discovered just how much of a difference each side could require in order to match each fork leg. It was about 20cc's difference.
So what is the fork oil level? well according to some of the other guys here who are much better than I at this,or at least much more experienced,  the level should be about 6 inches. My sons bike was suppose to be 51/2 so incles, 6 sounds reasonable to me and is what I am using. If you need them from bottoming out add alittle more oil and see what happens. too harsh remove alittle.


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

[Big Mac]

Thanks Thom. 260cc's adjusted to 6" from the top for the forks...Will use that as the 250lb rider baseline for now---and probably go to heavier springs later!

Do you or anyone else with Marzocchi shocks (Kip Kern?) have any manuals or reference info the sheds light on amount of oil recommended in the '77 shocks? Thanks, Mac

[rob w]

This was written by Dane in the # 25, Sept 76 issue of "Keeping Track"

"Rebuilding Marzocchi Gas/oil shocks"

-first install the inner steel tube in the shock and fill it with oil.

-Partially install the dampening rod assembly in the steel inner tube and begin filling the remainder of the shock body with oil. The shock body should be positioned in a vise so that the top bleed screw hole in the reservoir is the highest point of the reservoir. This will be about a 60 or 70 degree angle to the ground. This ensures that no air will be in the reservoir. When filling, the oil should come to about 1/4" up on the shock top threads.

-Screw in the bleed screw and tighten down the dampening rod assembly into the shock body with the dampening rod fully extended out. As the dampening assembly cap is tightened down into the shock body, oil will be displaced and seep out at the threads. This is how it should be done, because the object is to have no air mixed with the oil inside the shock.

So, I guess the answer is..fill it to the top, with no air inside.

I should probably just get a copy of this to you.

John Glover just sent me a bunch of Marzocchi shock info he received from "Cosmopolitan Motors", I guess they have all the parts and rebuild info as well.

Bob

[Big Mac]

Bob- That's the info I was looking for! Thanks a lot.[^] Hopefully there's some info on suggested gas pressure settings too? A copy of the Keeping Track article would be great if it sheds any more light-- a fax to Jon McLean, 503-684-7440 would be greatly appreciated. I assume Cosmopolitan Motors are the Moped guys, at //www.cosmotor.com? Didn't see anything on their site about Marzokes. If otherwise, a contact name and number is appreciated too. Thanks for all the help! Mac