Monoshock Spring Question

[QCRider]

Ok, can anybody tell me which of the following list of springs from Yamaha website is the stock spring for the '05 RX-1's?

1 8FU-47489-00-00 SPRING 1 (K=44.1N/MM) UR 1
1 8FU-47489-10-00 SPRING 1 (K=63.7N/MM) UR 1
1 8FU-47489-20-00 SPRING 1 (K=29.4N/MM) UR 1


I am looking to purchase a heavier spring, but I don't know which is the standard, or what weight rating they would apply to for the rider(s) of the sled. Any help out there?

 

[type787x]

QC, the -00-00 spring is stock, -10-00 is heavier, and -20-00 is softer.
Just FYI, my dealer rode one last year at a Yam dealer demo. He's a big guy, about 275 lbs with gear and he rides pretty fast. He said he wouldn't need a differrent spring, they purposley rode some pretty rough trail and used the remote adjuster on the tunel to dial the sus in. Said it definitley works. He also said something about being able to move the preload adjuster on the shock for way more or less preload but he wasn't sure how. Maybe you should test ride and see before you spend time and money on a different spring?
Just a thougth.

 

[Snorover]

There is a CD that comes with the sled that explains the adjustments that can be made to the suspension.

I adjusted the main spring one notch for me and my gear. There is an adjusting wrench in the tool box to make the adjustment.

If the dealer didn't give you the CD, ask him for it.

 

[QCRider]

I got the CD, and I also am about 275 all dressed out, and if it stopped there I would probably stay with the stock spring. The problem is that occasionally my 9 year old son will riding wih me on a Seat Jack on the back of the sled. He weighs another 80-90 pounds dressed out in gear. I guess I could try it and see how the stock spring works, but I was just looking for a little insurance to deal with 350 - 360 pounds of combined rider weight.

 

[type787x]

QC, I see your point. FYI, the stock spring is a 4.5 kg, the stiffer one is a 6.5 kg. Kg is the more common spec, not sure why they used the n/mm spec on the website.
Anyway, I'd still try the stock spring. Because I'm guessing your speed doesn't increase when your son is riding, and probably actually decreases, you should be able to adjust the stock suspension to keep your ride height up and get good results. Here's my suggestion:
1. Measure your rear bumper height with just you on the sled.
2. When your son is riding, increase your spring preload until the bumper height is the same as when you're solo. That way, your suspension is at the same position and angles as when you're solo and reacts the same. The ride will be softer because your son is helping to compress the spring but you can adjust that with the next step.
3. Use the shock damping adjuster on the side of the tunnel to make the shock action stiffer and keep it from bottoming.

If you end up with both the preload and the damping adjuster on full stiff and you still bottom, then you'll need a stiffer spring. But I'm thinking you won't. It's worth a try.

 

[tcona-AGT]

On the CD you got (no cd in Canada & the Yamaha rep doesn't know if or when one will be for sale here. )is there a scale or chart showing the relation to weight & the preload position on the shock?
Thanks for any setup info given for the monoshock.
Bill