I finished working on the forks from my GSX-R750 K8 this Sunday. I was able to take a short ride on the bike that afternoon and a longer ride on the way to work this morning. The results are simply awesome. Not just in the functioning of the forks themselves but completing the whole bike and how that works now. I can honestly say that I am a few clicks away from being finished with the basic tuning of an incredible motorcycle.
I went back and put the OEM 50mm negative springs back into the dampers. This was the right thing to do as the 75mm springs were too long and I couldn’t acquire any 60mm springs. The 25mm springs were not the direction that I really should have gone and I had to undo that.
I also decided to use the Ohlins .95 kg/mm springs that I had. They are just a little softer than the OEM springs and will be better for street. They are 5mm shorter than stock resulting in 10mm of internal preload with the spacers that I cut. The external preload is set at 0mm and doesn’t need adjustment right now.
Correcting the forks length issue was done with some Traxxion Dynamics top caps with 20mm of extension from OEM. They look great with the black forks. More importantly they put the front end in the proper position.
The bike really holds a line now with the very slightest of over-steer. It is so much easier to ride, is super comfortable, and just as solid as a rock on even the most twisty and bumpy roads. Riding to work this morning on Bolinas/Fairfax Road and Route 1 north of San Francisco tested the bike in some of the most challenging conditions you can find anywhere. I was constantly tempted to go faster, push harder, and trust the bike more and more. It’s a great feeling when a bike is set up at this level. Really, I just need to get back in the groove of riding and get my flow back. It’s been a while since I really was in good riding shape. This upcoming weekend is going to be pretty fun!
One detail that will have to be resolved at some point, the rebound adjuster is set at just 1/3 of a turn out. That’s not very good for adjustment range. I may have to replace the ISO 16 oil with something thicker, like ISO 20. It’s just a small detail but worth working out next time I have the forks apart.
Valving. I didn’t make any internal valving adjustments to these forks. Given that the forks damping seems to work well enough and that it came stock with such a heavy spring, I decided that I would just leave things as they are. It may be that the rebound needle needs some reshaping or that an additional shim is needed on the rebound stack to give the fork some adjustment range. I’ll look into this later. I’m just happy to ride things as they are now.
Another detail is that the oil height (OEM 115mm) may be a bit too high. It’s a little early to tell and I’ll know more after this weekend but it does seem like there is room for improvement here.