Question for 1200s forks on rubbermount owners ?

[jrclark19]

I've got the 1200S Forks with SE Fork Brace and Progressive 418 in the rear. I'm 200# and run the SE fork oil and just about stock settings for the forks. I'm not sure if if there is any more brake dive than the stock. I think the SE fork oil helped, but the other benifits would out weigh it anyways. IMHO

[Skyhawk1]

Originally Posted by XLXR

I weigh 230 lbs, still with stock fork tubes on 06 Roadster. One secret to getting the forks to work is using progressive or dual rate springs. The more compliant the front end is, the better the shocks can work. The more compliant the shocks are, the less the bike pounds on your back. Anybody who thinks rubbermount Sportsters must ride stiff and rough, have yet to figure this out.

I have gone from Race Tech .95 kg straight rate fork springs to Works dual rate springs with .715 kg initial rate, 1.1 kg final rate. I do not use the cross over spacer that comes in the Works kit. I still have the Race Tech emulator, but have reduced the compression dampening and gone to 5 wgt fork oil. I replaced the preload spacer with a rebound spring. That gives me triple rate springs. The emulator provides a bit of preload, but I can put the fork caps on by hand. Minimal preload, if the spring rate is correct, also helps achieve a plush ride. I have 13 oz fork fluid, that and the 1.1 spring really fix the dive problem. I have ordered the next lighter initial rate spring from Works, and hope that spring and reducing the compression dampening of the emulator a bit more will be my final adjustments for the forks. I consider fork brace and better tires (Metzler ME 880's for now) mandatory for us heavy guys. I run 30 psi front, 35 rear.

I still have Road King air shocks, 33 psi for sport riding, 27 for more plush on the highway. I don't know if I will keep them or not.

How does it ride? It is a whole lot closer to a Road King than new. It is also a whole lot closer to sport bike.

Heavier guys must go with heavier springs. A heavier spring inherently resists compression travel, but has more rebound force. Therefore, the valving needs to be changed to have less compression dampening, but more rebound dampening. The farther away from 180 lbs you are the more likely you will need heavier springs. The question is how to change the valving in the forks. I don't know if the stock adjusters will be enough, or if the internal valving of the S forks can be changed to match the heavier spring.

Interesting stuff. I'm not really all that familiar with the how you have this set up. You're using a rebound spring(which one) instead of a pre load spacer but why no cross overs? How did you determine the the spring rates? Just looking at the application guides on their web site I can't figure out whats what there in the way of spring tensions or part # for an 06.

John

[XLXR]

The rebound spring, also called lowering spring, came in the Works dual rate fork spring kit. I don't know the actual spring rate. The Works kit comes with 3 different crossover spacers that you can use to limit the travel of the initial spring at 3 different points at which the light spring stops compressing and the heavier spring continues to compress. This creates a progressive rate fork spring. Being able to fine tune the overall spring rate is a major advantage of the Works Dual Rate fork spring kit over progressive springs from Progressive Suspension.

I also went from stock shocks, to Progressive 440's to Works Pro Racers, all garbage. I sent the 440's and Pro Racers back. I bought the Road King air shocks just to be able to ride the bike. Eventually, I decided to ignore what the experts from the aftermarket suspension companies recommended and started doing what I felt the bike needed. I noticed the rebound spring was about the right length, so I stuck it in there. I went from Race Tech recommendation of 20 wgt fork oil to 15, to 5 just to see the effect. I tried several different oil levels until I found 13 oz worked best with the springs and emulator I'm using. As to figuring out the spring rates, I just keep changing them until they feel right. The truth about the crossover spacer is that one time I forgot to put it back in, did a test ride and liked it better sitting on the bench.

But I'm not done yet, the new springs came in, give me a few days to get them in and do more test rides. I'll let you know how they work.

I am an old dirt biker. I have always had to do custom supensions. But never had so much trouble before. If this is all greek to you, read up on the web sites for the aftermarket suspension companies and on line motorcycle magazines, like Sport Rider. Get out in the garage, make changes and do test rides. Don't listen to guys who say the Sportster has to pound you.

[XLXR]

Just got back from installing the new lighter weight initial springs. Paper work says 80 lbs. Other than being a lighter spring rate, I don't know how that compares to .715 kg of the springs I took out. I also loosened up the Race Tech emulator compression dampening by 1/2 turn again. Both the front and rear of the bike ride softer. I was able to reduce the air pressure in the shocks to 17.5 lbs. The lowest I ever ran. This is the most comfortable ride I have ever attained. Feels like a real motorcycle.

With the lighter initial spring, the fork has more dive and rider sag to it. So what I have done is to find the heavier spring is a bit too heavy (stiff ride but less dive), and the lighter spring is bit too light (soft ride, but more dive). That's the compromise and I will need to decide what to do next.

Here's my options:
1. increase oil weight and / or compression dampening - nope - I want to keep the front wheel as compliant as possible.
2. take out that rebound spring out and replace it with regular preload spacer to add more preload - maybe
3. put in the shortest crossover spacer to limit dive from the soft initial spring - yep, because that will retain most of the initial travel plushness and get to the 1.1 kg final spring sooner in the fork travel to mininimze dive.
4. see if I can go even lower on the shock pressure and rebalance front and rear rider sag by lowering the triple clamps on the forks - absolutely.

8 months and 8,765 miles since I bought the Roadster, I finally have found what nobody could tell me. The perfect fork spring rates for me. Still some fine tuning left to do, but I seriously doubt I will change springs again.

I know the original question was about S forks. I don't know how much of the specifics will apply to you, but I hope this give you a better idea of the process you must go through to make it the best it can be.

[XLXR]

A few test rides left me feeling the initial fork travel was too soft and too much dive. I took out the one inch long rebound (lowering) spring and replaced it with one inch preload spacer. I still left out the crossover spacer. Much better. The front end stays up higher in corners and feels firm and well planted, but more commpliant with the road. Next step is to reduce compression dampening on emulator again, just to see what happens.

[whittlebeast]

XLXL

We need pics of how all this stacks together. I am still trying to fight that desire to take the front end apart. At this point the only thing I dont like is the ability bounce the forks on full compression OCATIONALLY. It takes a handfull of brakes and a bump at the same time to do it. Under normal riding my Low is right in the center of the available trravel.

AW

[XLXR]

Unless you feel a problem while riding, leave it alone.

... only thing I dont like is the ability bounce the forks on full compression OCATIONALLY.... - I don't quite understand what that means?

Do you mean the forks bottom out occassionally? A rare, but gentile bottoming out on the worst bump you hit is OK because that indicates you are using all the fork travel.

Do you mean that after all the compression travel is used up, then the fork rebounds (extends) too much. (I think you use the word bounce.) If that is the case, you need to add rebound dampening. Problem is there is no adjustment to add rebound dampening by itself, except weld up one or two of the rebound holes in the dampening rod. You can go to heavier weight oil, but that increases both compression and rebound dampening, but that is a common solution.

You might want to try to add a bit more oil to the forks to increase bottoming resistance. That does not affect the initial fork travel, keeps initial plushness. I have 13 oz in mine, 2 or 3 more the service manual says. Too much oil can cause hydro-locking.

Like I said, unless you have a big problem, leave it alone. On the other hand, the only way to try and improve it is to try different things.

Next time I take it apart I will try some pictures. I am to lazy to figure out how to post pictures. Maybe somebody will post pictures of the picture in the service manual. They have done it before.

[whittlebeast]

During hard braking when I hit a bump I hear a metalic "BANG". I have to go out of the way to get it to happen. The wife may never feel it at her size.

AW

[XLXR]

You're too heavy for the fork spring rate, too little compression dampening or too little fork oil. The easiest fix is to add 1-3 oz more fork oil, avoid hydro-locking. Your wife will never know.

You are not riding the bike the way it was supposed to be ridden. You are exceeding the design parameters of the bike. You are an unsafer rider. Do not tell your dealer, he will void all warranty coverage. Do not call HD, they will keep your name in the crazy file forever.

[whittlebeast]

I am so proud