The FJR's Stock Suspension SUCKS!

[Fred W]

Hello Fred,
How reliable are your numbers on the preload of the springs for the Gen II?

Quoting Fred:

"The spring free lengths are almost the same (261 - 262mm), and the spacers are the exact same length (149.5mm) but the installed spring lengths are a tad different (due to the fork internal dimensions) at 246mm 1st gen vs 251mm 2nd gen.

In the case of the 1st gen fork, the spring is pre-compressed by 15mm when installed (difference between spring free length and installed length), so the spring pre-load will be 15mm x .8kg/mm x 2 forks = 24 kg. Second gen preload will be 11mm x .85 x 2 = 18.7 kg."

I am in the process of installing RaceTech springs - longer than stock - and want to use your numbers to calculate how much of the spacer I need to cut and achieve the correct preload. I am using .95kg/mm springs and shooting for a preload - adjusters completely backed off - of 13 to 14 mm

Thanks

My numbers were all taken directly from the Factory Service Manual, so they are accurate for the stock springs.

However, the amount of pre-load that will be required for a set of replacement springs will definitely be different than what was used on the softer stock fork springs. That is kind of the point of replacing them.

You best bet on determining the preload, so you can calculate the correct spacer length, is to contact the manufacturer or seller of the springs to get that information. They should be able to calculate the preload spacer length based on the spring length, weight of the bike, your weight, and your anticipated riding style.

Otherwise it will probably be an iterative process of starting with the spacer too long (too high of a spring pre-load) and incrementally reduce the spacer lengths until you get your loaded sag right to get it correctly dialed in.

 

[Klunkshift]

Thank you Fred.

The numbers are a good starting point as you mention. Suspension tuning is an art and a personal issue - what I like may be harsh or mushy depending of the user.

RaceTech recommends preloads etc through an online calculator. These initial RaceTech numbers may be a good start, but need to be fine tuned with user input.

This is why I ordered a few extra OEM spacers. They are a cheap investment for a possibly long process of tuning the front suspension to my liking.

 

[RiderX]

Race Tech calculator produced something like .97 kg/mm for me. Once on site, Installer Tony told me for a Gen2 they like to use 1.1 (for my 200#) and ended up with 1.2 for my dash shelf extravaganza. Almost as if the sales guys tout the calculator and the installers have another opinion. The stock spring rates were not correct either (online).

 

[RPrice]

I've read every post in this thread, and I don't think anybody mentioned servicing the front fork occasionally to improve the performance. Last Fall, I "bit the bullet", bought all the parts, purchased and fabricated the tools with the information I gathered on the subject from this forum. I replaced all the bushings, the fork seals, dust covers, etc. and replaced the OEM fork oil with Motul Light 5w.

I'd always had my fork set via the Warchild recommendation and after servicing returned to the same settings. Wow, the difference in performance was very apparent. Much more planted in the corners now. A much "tighter" feel to the front end.

The fluid I drained from the tubes was kind of a grayish sludgy mess, and I did this work at 24k miles. I'm not sure what the fork oil would look like at say 50 k miles, but I'd bet it would not be pretty!

Just saying that this service, though not recommended maintenance in the manual, really can help. Surely not as much as an aftermarket suspension, but it does help considerably. At least in my experience.

 

[str8]

I've read every post in this thread, and I don't think anybody mentioned servicing the front fork occasionally to improve the performance. Last Fall, I "bit the bullet", bought all the parts, purchased and fabricated the tools with the information I gathered on the subject from this forum. I replaced all the bushings, the fork seals, dust covers, etc. and replaced the OEM fork oil with Motul Light 5w.
I'd always had my fork set via the Warchild recommendation and after servicing returned to the same settings. Wow, the difference in performance was very apparent. Much more planted in the corners now. A much "tighter" feel to the front end.

The fluid I drained from the tubes was kind of a grayish sludgy mess, and I did this work at 24k miles. I'm not sure what the fork oil would look like at say 50 k miles, but I'd bet it would not be pretty!

Just saying that this service, though not recommended maintenance in the manual, really can help. Surely not as much as an aftermarket suspension, but it does help considerably. At least in my experience.

+1
Did mine at 40k miles. Too long!

Before dumping the old oil I checked the level in the forks. Both sides were low, right side over an inch low. I knew the seals were seeping, but I didn't think that much!

 

[AKjitsu]

The fluid I drained from the tubes was kind of a grayish sludgy mess, and I did this work at 24k miles. I'm not sure what the fork oil would look like at say 50 k miles, but I'd bet it would not be pretty!

Hmmmm...... Kinda makes ya wonder if Skooter found a new place to plant boogers.......