Hello guys, would somebody share oil viscosity and levels for club racing on F1 or TT ( with no exotic valves inside...)?

I think this has been posted before. I do not remember who wrote this:

Marzocchi M1R Specifications

The following information supplied by Marzocchi in Feb.1986
and should be use for the 1989-90 Ducati 851 and SP versions,
Bimota DB1, S, SR series motorcycles.

This what I have found and what actually worked well for me (170 lbs)
And my son (120lbs).

GENERAL INFORMATION
The right fork assembly controls rebound (knob at the bottom of the fork slider) and the left fork assembly controls compression (no control anywhere).

Different levels and different viscosities of oils can be used to suit conditions. This is the beauty of these forks. Adjustments on each leg will not effect the other. Only fork springs and oil levels need to remain the same. Oil viscosity can be varied on each leg if you are competent enough to judge and appreciate the differences.

Fork Springs
There seems to be misleading and inconsistant information on the springs for the M1R forks. There are 2 springs, one in each leg. Some parts breakdowns will only show one and even Marzocchi literature is misleading when it actually shows NO SPRING in the crossection of left fork tube. Trust me.......there ARE 2 springs.

Marzocchi has different fork springs for the 42mm M1R forks which are:
Light Spring-------30 inch/lbs---------Part # 18.0071
Medium Spring ---40 inch/lbs---------Part # 18.0072 (standard)
Heavy Spring-----50 inch/lbs---------Part # 18.0073 (standard)

Progressive Suspension has springs (Part # PS 1130). They work extremely well especially with the adjustable preload caps (no Part #) on pg. 7 of the Pro Italia, June 1994 catalog. These adjustable caps were made for the Ducati 750 Paso and the 907 Paso.


FORK TUBES
It appears that the right and left fork tubes are of different lengths as supplied on a motorcycle and there are different lengths available.

YOKES (Triple Trees)
Different offsets and stem diameters are available.

OIL LEVEL(s)
The oil level is measured from the top of the open fork tube (cap off) to the centerline (repeat: centerline) top of the oil inside the upper fork tube. Take the springs(s) out and compress the fork completely to
Make this measurement.

38mm tube models should have 160 mm of air distance from top
42mm tube models take 170mm of air distance from top.

I recommend you buy one of the many availble fork oil measuring tools that look like a very large medial syringe with a long tube where the needle would be. On that tube there is a sliding disc that will rest on the top of your fork tube. The idea is to put a large amount of oil in the tube and then(with the tool) you suck off the unwanted oil and then repeat for the second tube. Simple and very accurate.....IFthe forks are vertical.

Use 5 weight oil for temps 10-15 centigrade (30-50 F)
Use 10 weight oil for temps above 15c (50 degrees F )
Adjust the oil viscosity to suit temps. There is 2 wt oil for colder temps and you can "play" with mixtures as you desire and learn.

The right fork leg with the knob down on the bottom is for REBOUND and has 4 (yes only 4) positions. You can rotate past 4 and will go back to 1 after you get the oil and spring(s) installed you should be able to tell the 1 position from the 4 position.There are different springs in the REBOUND adjustment (knob area) to adjust the range of rebound dampening rates (not to mention you can play with oils).

Light rebound: Spring # 71.0050
Medium rebound: Spring # 71.0051 (nromal)
Heavy rebound: Spring # 71.0052 (normal)

Use no air in these forks. From time to time you will need to bleed off unwanted air that gets trapped in the forks.

MODIFICATIONS TO FORK LEGS (Tubes)

In March 1986 a Marzocchi service bulletin recommended:

Left tube: drilling a 6mm hole, 65mm from the bottom of the fork tube
Right tube: drilling a 6mm hole, 35mm from the bottom of the fork tube.

BE CERTAIN TO "DEBUR" THIS HOLE AND SMOOTH EDGES OF
DRILLED HOLE AS BEST POSSIBLE.

ricambi.spa@marzocchi.it has the Marzocchi service manual & parts book (one book) and spares.

Thanks, I know those specifications, I only want to know the experience and modifications from pilots.

Hi, I have an 851 with these forks , I have some notes of what I done to suit my riding. I will try them. Boucher.

Many thanks

Hi this is what I've done to my 89 851.
L/h fork, compression side I put the oil 160mm from top with fork collapsed and no spring and I used belray 10wt.
R/h rebound side I put the oil 160mm also from top but used 5wt oil.
I had the forks setup so there was 25mm out through the top triple clamp.
And finally I'd put two hardened washers each side under the fork caps (3.00mm) to increase spring preload. Hope this helps. Boucher.

Thanks Boucher

I’ve tried rhd/5w/170 and lhd/12,5w/175, I will try to fill more

some rambling.

i had my 851 done with gold valve emulators years ago. it had 0.85 springs fitted - race tech FRSP S353485 which were a bit too soft as it would bottom out under hard braking. oil height was 150mm i think. i then went to 0.90 springs, not sure if i raised the oil height or not. nowadays i would go after the oil height more aggressively.

raising the oil will increase the air spring effect, nothing else, so if it's not bottoming no need to go higher. don't recall what the oem spring was. i'd probably go lower on oil level if it's not bottoming out so you get to use more travel or have better absorption of bumps when loaded - ie, braking hard into a corner. when it starts bottoming out, go back up 10mm.

i did a couple of late 80's 750 sport recently where i cut the springs down from 40 to 32 coils to go from 0.72 to 0.90kg/mm and dropped the oil level to 200mm. at 150mm when bounced i couldn't get them anywhere near compressed, at 250mm they bottomed out easily. 200mm seemed like a good start.

a spring rate 0.85 or so is a good start on a light bike, the 0.90 better for a heavier road bike i'd think. 15mm of preload tends to give about 35mm sag on normal things.