nc23 usd forks upgrade

[lloydiecbr]

has anyone fitted usd forks on a nc23 . i would like some advice as im thinking about doing it next winter to my nc23-600 that im building .any help will be great thanks :)

[firebeast]

got rc45 legs on my project.
you can make anything work provided you do your homework and measure it all up before buying anything.the rvf4 forks are gonna be too short as the 23 is longer than a 29 and they dont fit that.also the spacing/height for the calipers is important.
zxr4 has been done but a set of zx6 with radials or a similar suzy or honda would mean when you have centre'd the wheel,rather than make brackets(can look tacky sometimes) to mount the brakes,you space the discs to suit the caliper and shim the caliper up or down to suit.provided your discs are big enough.else its taking the mounts of the calipers which is a bit naughty.or get bigger discs
the 23 uses a long stem as well so expect to have to get someone to flypress it out and put it in the new yokes.unless you get some of those made as well!
they may also need new springs etc to work better for your bike.

[squirrel_hunter]

That is my NC23 with a ZXR400 front end.

It one of those long running project things so its not complete and this isn't a how to guide.

For reference I am using a ZXR CBR hybrid yoke. I got a local bike engineering firm to make me one using the bottom yoke of the ZXR with the stem of the CBR pressed into a collar and the bottom yoke. I opted for this in the hope to use the standard bearings and because IIRC the ZXR is a little short. From what I found the clipons will fowl the fairing or frame if you have them in the standard way. What I did was mount them on opposite sides as this also improves the angle on them, I just need to make a spacer for the bolt. And on the subject of spacers I need to make one for the front wheel spindle as having the ZXR speedo drive there is a little pointless. I think I might just smash the one I have apart, but that does seam a little bit of a waste as it is a working unit.

My bike is far from finished, the project has somewhat stalled. However this frontend swap still has a couple of outstanding issues. The first as shown in the pic below, the lock stops need to be built up. So I need to find myself a good ally welder to do that for me, the plan is to get them built up then drill and tap them to install a bolt to allow me to adjust them, alternatively I'll just get them over built and have fun with the Dremal.



The other problem is the geometry change. The forks are slightly shorter but they are offset further out, so by my calculations by having the fork top flush with the top yoke there shouldn't be much of a difference. But time will tell; I fear it will be a while yet before the bike makes it back on the road. Anyway not sure if thats of any help/ interest, but if theres any aspect of this that you need a hand with I'm happy to help.

FireBeast makes a valid point about the wheel. To over come this I am using a ZXR front wheel. That does mean that I will have a mismatch with the rear unless of course I can fit a ZXR to the rear...

However I started this long before I knew that the ZX6 could fit also. So in true "I've started so I'll finish" style I'm sticking with the ZXR400.

[lloydiecbr]

thank you all for all your advice . i think i will have to do alot of resurch and a lot of saving ! as this aint an easy thing to do . and i thought putting a 600 engine into a 400 frame was hard . but the day will come for usd forks ..

[squirrel_hunter]

Yeah the best thing to do is not to think of the cost. I'm not going to post what I've spent so far on it as I think that will make me cry.

[firebeast]

know what you mean,as i am useless for getting it started up again,i have got zx10 forks with blade radials sat around waiting(also spare set of gsxr radials if you know anyone),plus ap thumb brake and dual control rear caliper to fit.dont even ask.i will eventually try grafting on a r6 airbox onthe mota,to go with an r6 tank/subframe.
some time in the next decade!
want to put the rvf forks on my vfr750 with sp1 calipers.

[squirrel_hunter]

R6 airbox? Thats a new one on me, any performance benefit or is it required for the R6 tank?