2001 900ie Suspension setup

[Gimpy]

After riding this bike for the last 2 years I've decided I hate the suspension.  I figure I better get to work fast while its raining.  I went out and got a Penske rear shock, and a set of adjustable 900S  Showa forks.  I know the forks are not much of an upgrade but I didn't want to go through the whole thing of modifying the triples. 

I have been doing a bunch of research, and I figured I would get everyone's opinions from here. I am 200lbs in gear, not setting up for track use, and need to find a compromise between feeling planted in the twisties and smoothing out the ride on some pretty awful road conditions. I think a smooth ride is more important to me if I have to choose.

For the rear shock can you just exchange the spring to get one with the proper specs or do you buy the one you need.  Penske says I need one that is 7in long and rated for 600lbs, which makes sense.

On the front forks I had previously changed the fork oil down to a 5 weight to try to smooth out the bumps.  It seemed to make the ride better, but still divy and harsh.  On the new set I am going to get the correct rated springs.  Should I get them from Racetech? Are there any other suggestions? Does .90kg from the calculator sound about right? What weight of oil should I put in? Should I maybe try adjusting the amount of oil in the forks?

Thanks in advance for all the suggestions

[Slide Panda]

Well 5 wt might be part of the problem.  Stock is 10 wt... if the oils too light that gives you too little damping, which makes for harsh ride.  More of the hits the forks take is transferred to you and not absorbed by the oil.  The divy nature of the forks was attributable to your springs being too light for you... harsh too little damping. 

I'd give race tech a call.  They have done M 900S in the past for someone about your size.  They keep notes on just about everything so they can suggest the right spring rate for your weight + the bike. 

[EEL]

Are you sure stock is 10wt? Dont quote me on this but the 2001 900's had an adjustable showa similar to the newer bikes. I believe those took 7.5 wt stock..

All in all, I agree with the previous statement. Its divy because you're running too light an oil. Lighter weight oil will screw with your rebound as well, making your suspension hop back up really fast adding to the harshness.

Confirm oil weight and stick with stock setup. Unless you're a hard core suspension guru or you race, you should only change your oil weight if you revalve.

[txduc]

+1 on the oil wt.  My 99' 900s w/ the adjustable Showa calls for 7.5.  If you have a tough time finding 7.5 check out a local BMW shop.

[Gimpy]

Well I'm not a hard core suspension guru, but I have to do something. Pretty sure the oil in the non-adjustable Showas  was 7.5. I cannot be sure cause I bought the bike used.  I switched to 5 because the front forks felt wooden and stiff.  The 5 weight helped but it wasn't enough. Now I have the adjustable Showas and I'm thinking of going back to 7.5, but I'm open to suggestions. 

Another question is how much oil to put in the forks? I don't really want to rely on putting the amount of oil that was in the forks back cause I  bought those used.  Does anyone know the stock level or volume? And what effect does raising or lowering the oil level have?

[2001cromo]

Stock oil is 7.5 in the forks. <-- I just confirmed this with my 2001 M900 shop manual.
And in terms of spring rates the 9 is right in the range of what you're looking for. The higher the # the firmer it gets, but you already knew that from what you're describing. I'm about 215 without gear and I've got 9.5/10 front/rear and it feels great. And I beat the snot outta my bike. 

Make notes of everything you do so you know where you are and can make adjustments easier (instead of blind).

The racetech springs are more tightly wound at one end and will not go over the plastic guide that's between the damper rod and the cartridge body. So you have to remove this plastic guide to make them fit. (I've NEVER seen a set of racetech's that didn't) And besides that little plastic guide always ends up breaking into little bits in there anyway so just remove them. <-- I wouldn't be surprised if you find plastic bits in there when you take em apart...

Or send your forks out and have someone do them for you cause you need a few more tools to do the job that you hopefully will not be doing again... same cost for tools as to have someone do the work who knows exactly WTF they're doing and will change the valve stacks to something that actually works in both crap conditions and pushing it... <-- just my 2 cents here

Also if I were you I'd get a steering damper if you dont' have one already. (it's cheap insurance)

In terms of front and rear ride height, that's very personal and it really depends on what you want the bike to do... Most will say "keep it stock" and that's fine if that's what you like/know.

But before I did anything I'd measure where the bike sits now so you know where you want to go or at least get that back to the same place once you've got the spring rates and valving setup.
And remember "Make notes of everything you do so you know where you are and can make knowledgeable adjustments easier."

Good luck!

[ducpainter]

Stock forks are under sprung and over damped.

Correct springs will help you a lot.

Or you could send them to someone to have them re-worked. It will transform the bike.

2001cromo and I are thinking along the same lines.

ducvet would be a good choice.

[Slide Panda]

Hmm ok.  My forks were re done w/ race tech valves and 10 wt.  - so there's a couple things that got monkeyed with in my case.  But consensus is factory is 7.5

Another question is how much oil to put in the forks? I don't really want to rely on putting the amount of oil that was in the forks back cause I  bought those used.  Does anyone know the stock level or volume? And what effect does raising or lowering the oil level have?

For a 2000 S (adjustable Showas) the oil level is 108mm from the top of the tube.  I just did the oil in my forks so that # is fresh in my head.  I'm not sure if it varies if you have different forks though.