Dannyvirk wrote:If you use a u.s.d ZXR front end try if possible to go for the 'R' model for the 750 or 'SP' for the 400. As they have an additional adjustment in the form of a dial located on the same casting the axle goes through and face backwards. On the standard fork there is just an unmachined plug in the casting.
On older ZXR750 front ends i've seen, sometimes the chrome worn through, so i'd check that before buying it as some of these front ends are over 20 years old. Not sure why the chrome fails, it may just be natural wear.
The spring rates will be completely wrong, regardless of playing with the dampening.
I'd be interested in the weight difference between ZXR and NSR forks, both in terms of sprung and unsprung mass.
I think at the time (early 90's, or 89 onwards for the 400) these fork represented a major leap forward, and this contributed to ZXR's reputation of being planted at the front.
Still for the amount of time it takes to change the front end over i'd spend the extra money and get later model front end with radial brake calipers even if it is mainly for aesthetics reasons and also i suspect the later the model year the easier you may be able to find something off the shelf to resolve the spring issues.
I agree with everything you just said, no doubt a newer model front end would be much smarter.
However, the bike came with the Kawasaki forks and triples, which cost me nothing to keep. A little bit of work on the caliper brackets was required, but in all it was a lot cheaper to keep it on. Plus surprisingly the offset/trail etc can be kept pretty much as standard (slicks notwithstanding). I also keep the NSR brakes running on a 3.5 inch RVF wheel with the 296mm rotors. Ok they are not super modern, but it keeps the 'time piece' look while still being much better than standard. I think maybe I have spent about $400. Not too bad but it would have been much more to do it from scratch. No doubt a newer front end would be much smarter there.
Thanks for the good ZXR specific advice about the forks. Mine are pretty much mint on the chrome so I am lucky there, but I must have the base model ones as there is no dial adjustment where you say. What did this adjust specifically?
The forks have been resprung (again not by me) but I suspect that they are still too hard. Even so, I've been amazed at the stability and response from these forks when really pushing the bike hard. A test day is what I need to see what my next move is with the spring rate. The ZXR forks have a heap of available travel (which is maybe best not fully used) so it will be a case of adapting the setup to the lighter weight