Can't help exactly with spec but this I think is somewhere in our documents sections I do have the full transcript (not a lot more).
But this may give you some measurements to be going on with?
As you can see the springs are different and also come in various sizes by the look of it and to add to that you may have a part added that isn't actually shown in the parts breakdown manual!!!!!
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.
38mm tube models should have 160 mm of air distance from top
42mm tube models take 170mm of air distance from top.
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)
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.
