Fork seal/oil question '99 M900S Monster

[jc]

My Haynes manual isn't exactly clear on which models it is referring to. I'm replacing the seals on my 99 M900S with fully adjustable stock Showas.

If someone could help me out I'm looking for info on the correct measurment from top of tube to oil, total CCs that I should be putting in, type of oil I should/can use and any special process that isn't outlined in the manuals for adding oil, purging air, rechecking oil and adding more.

Any other info I might not have asked for but should/need to know is appreciated also.

Thanks in advance.

JC

[burnticarus]

I have a 99 M900S too,  I haven't done any work on my forks yet,  but I do have a shop manual for M 900.

The Shop Manual I have states under Front suspension:

The front suspension is equipped with oleodynamic fork with reversed legs.
Bearing pipe diameter mm/in.............................41/1.614
Stroke mm/in.................................................120/4.72
Oil quantity (each leg) cc/cu.in.........................457/27.8
Oil level mm/in. ...........................................79,4/3.126

not sure if that really helps you or not

[burnticarus]

Also found this:

Oil should be filled (oil: SS8, volume: 27.87 cu.in.)

Says:

Remove the air in stroking inner rod more than 10 times.  Remove the air in stroking the outer tube slowly in several times.  Be careful not to pull the outer tube too high (about 100 mm/3.9 in. stroke).

After leaving it in a few minutes, the hight of the oil should be arranged in a condition of inner rod and outer tube, maximum compressed.  Oil level: 79,4 mm/ 3.12 in.

[scott_araujo]

Don't measure CCs of oil.  Measure distance from top of fork tube, it's more accurate.  Damper rod and outer tube should be fully compressed, everything except the spring installed.

Here's a YouTube video that demonstrates a fork rebuild including oil fill and air purge:
Fork seals, change on motorcycle part 1 (of 2), twin chamber

This is part 1, should be a link to part 2.

Scott

[dlearl476]

I have a 99 M900S too,  I haven't done any work on my forks yet,  but I do have a shop manual for M 900.

The Shop Manual I have states under Front suspension:

The front suspension is equipped with oleodynamic fork with reversed legs.
Bearing pipe diameter mm/in.............................41/1.614
Stroke mm/in.................................................120/4.72
Oil quantity (each leg) cc/cu.in.........................457/27.8
Oil level mm/in. ...........................................79,4/3.126

not sure if that really helps you or not

FWIW, the shop manual I have only describes the non-adjustable forks.  I used this info from mine as well, as it's all I had.  I don't know if the adjustable fork info came as a suppliment or what, my manual doesn't have it, nor could I find any info on the web.    One further note: in the reassembly part it describes "Oil Type SS8."  On advice from RaceTech (I installed Gold Valves as well) I used 7.5 weight and it's fine.

IMO, the video Scott posted is the best info I could find re: the process.  And I found two tools, RaceTechs fork spring compressor and rod extenders invaluable.  They're expensive, but worth every penny IMO.

[scott_araujo]

I have the non-adjustable Marzocchis.  I was ready to buy both those tools but ended up not needing either.  It was easy enough to do all by myself with no special tools.  I only did the spring install and oil change though.  When I rebuild and change the bushings I'm sure I'll need some tools.

Scott