INSTALLATION NOTES: SUZUKI GSX1300 HAYABUSA rear shock

[justplainbill]

I wasn't planning to post a report on changing my OEM FJ-09 shock for a used with 8400 miles, 2006 Hayabusa unit (and didn't take photos), but the project had so many surprises, listing those might be of value to someone else.  Starting with what I knew before starting the process:
 
1. Removing the tank is a PITA but of course essential to the exchange.
2. Physically, the Busa shock is quite different than the FJ-09 shock: the pre-load adjusting rings are at a the top of the shock and inaccessible on the FJ, there's a huge gas/oil reservoir above the top mount, the Busa spring (rated 13.1 Kg./mm, 733 lbs./in) is much stronger than the FJ spring, (10 Kg./mm, 545 lbs./inch), and finally, the Busa shock offers compression damping adjustment. Other than that...the eye to eye length is the same (13") and they can be interchanged.
 
Before starting, I replaced the stock spring with an Eibach spring having a rate better matched to my weight (200 pounds -- part number 0800.225.0650).
 
What I didn't know or expect:
 
1. The shock reservoir is slightly wider and higher than the channel formed by the plastic tray(holding the ABS module and various electrical connectors) it has to pass through to the front mount. It takes considerable effort to push the shock through the channel and requires sawing a cut in the channel sides back about three inches to allow the channel top to bend upward and outward to allow the reservoir/shock to emerge at the forward mount (think of an episiotomy at a birthing). It's also necessary to separate the three forward electrical connector ends during the process for the same reason. 
 
2. During removal or replacement, for the shock to clear the swingarm mount, you have remove the rear wheel or raise the motorcycle higher than the center stand by itself can. In the second case, having the front tire secured in a wheel chock with tie downs for stability and scissor jack to get the extra inch or so of height is helpful (or necessary if working alone).
 
3. If using an aftermarket spring, before installing the Busa shock, adjust the pre-load to take up approximately one third of the thread on the shock body. Eibach and RaceTech springs are eight inches long while the stock Busa spring is a quarter inch shorter and has a higher spring rate. So you need less take-up to get in the ball park. 
 
4. Consider the initial pre-load adjustment and installation as tentative and don't bother putting nuts on your mounting bolts before checking your sag. That's because there is no way to use a C spanner to adjust the rings with the shock in place and using a pry bar would likely do more damage than good. After checking the sag (static and race) be prepared to remove the shock and make adjustments off the bike. In my case, I found that one full turn tighter of the adjusting ring made a three mm change (reduction) in race sag. YMMV
 
5. A minor issue; on the Busa shock, both damping adjustment screws face the left side of the bike. While changing the spring, I managed to turn the shock shaft and lower mount 180 degrees so the rebound adjustment screw faces the right side of the bike. Not a big deal, but if I had it to do over, I would leave both adjustment screws facing the left side. 
 
Those are the important things I learned about the installation. As for any gains from replacing the stock shock with the Hayabusa unit and a higher (than FJ) rated spring, my first impressions (with very little testing and adjustment done) is that the back end handles small sharp bumps (cracks in the road, tar strips, etc.) very well now but pot holes are still harsh. (Race sag is 26 mm, both compression and rebound damping are opened up two clicks from center (toward softer). And, since the main advantage of the Busa shock over the FJ shock is adjustable compression damping, I can state that softening the compression damping made a noticeable improvement.  Hopefully there are more improvements to be found with more testing.
 
If I hadn't been planning to change the stock spring anyway, I'm not sure I could justify the time and work needed to install the Busa shock for the gains (so far). But, as long as I was going to R&R the OEM shock spring anyway, the extra work and expense of the Busa shock (just $60 on eBay) was probably worth it. Though how much of the gain is due to the spring and how much to the shock is uncertain.
 
 

[adjuster]

Bill, any updates on this shock?
I have just bought one myself, and thanks for the spring data,

[justplainbill]

Bill, any updates on this shock? I have just bought one myself, and thanks for the spring data,

I still think it's a worthwhile modification Adjuster.   The one memory I have of rides, is that I have no memory of the suspension, which means either it's working well or I'm used to it. Well, I'm still aware of those damn expansion joints on some roads but it's just that they are repetitive and that makes them annoying.  Good luck with your install.

[adjuster]

Thanks for the review. No memories in this case are good.
 
I found one slightly used, off a 2012, and it's so clean I can't imagine the bike it came off had more than a few thousand miles if that. Seriously it is like brand new.
 
I'm not happy to say it, but I'm on the larger side of riders, more like a continual two up riding load, and I think the Busa spring rate will be just about right for me. I was thinking of adding some pre-load prior to installing it, but am riding fully pre-load added right now on the stock FZ09 shock, and it's not that bad. (The FZ09 was terrible for my weight, it was a like riding a kid's spring suspended plastic pony/hobby horse.)
 
When I used to ride the KTM's, they were always too soft, but with the range of adjustment available, I never had to change out springs, only added all the pre-load and fiddled with the adjustments for compression or rebound and they were fine.
 
The 2006 FZ1 I had was the first bike I've ever changed out a shock on, and even then I went with an upside down R1 shock, and made my own custom 3 point link plates. Everyone griped about the 2006 stock spring being too high, but I wanted that rate, and changed the FZ spring over to the R1 shock, and that was a serious PITA, as the two are not the same static height at all. (Had to use spring compressors on the FZ spring to get it to engage on the R1 shock, but when it was done? Heaven! The high/low compression and rebound settings made it soft enough over bumps, while the spring rate handled way better than the stock setup. And on the forks? Just cranked then down to where the last ring was showing and left it there, and it worked fine.
 
I only had the 2014 FZ09 until the engine consumed it self due to the bad CCT, then traded that for a 2015 FJ09, and have not regretted it at all. Much better bike, much better setup for me as well. Don't get me wrong, the FZ09 was a hoot to ride, it felt like a pit bike, or medium sized supermoto when I rode it, and that was great fun, and had plenty of power, but the suspension was TERRIBLE>
 
I know the FJ09 is supposed to be the same basic bike, but the suspension is much better, and I like the HID's, windscreen and slightly more "Grown Up" attitude. (And my insurance rates went down by more than a thousand dollars a year.... no joke, I was shocked.)
 
One last question. Did you leave the "Flap" of cut plastic over the Busa shock remote bladder? It seems like it would just move slightly against it when the suspension moves, but should not wear out anything important. And it would keep anything you put under the seat. While just having it open and missing would allow stuff to drop out.