I have been using a VFR400 front end on my '21 for about a year and it works well apart from being a little soft. I have a ZXR400H with USD forks with a blown engine as a donor. Is it an easy conversion and is it worth it?
Why don't you consider a more modern front end from say a ZX6r? if you are going to go to the trouble of a stem swap or yoke conversion it makes sense to take advantage of the developments that have taken place.
Are you looking at the ZXR400 because they are a straight swap?
I would imagine the ZXR is being considered because it's already in his posession, so there is no initial outlay for the forks themselves.
I too would say that a more modern front-end would be a better choice though. ZXR400H forks would be after all, 80's technology, and possibly a step backwards even though "looking" better than a RWU setup. _________________ Andy.
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Ah missed the point of the got them already bit, that makes a difference. However ZXR400 stuff is pretty saught after by racers so part it out and buy a set of more modern forks.
If you go for the ZX6r ones I can help with caliper types that will fit (loads) and a few other bits and bobs. Cheap if you buy from the states.
As far as I am aware, there's nothing really "wrong" with a ZXR400H front-end, but I don't think it's particularly sophisticated either. If you have the forks and just want the look of the USD setup, then I can't seen any harm in it, but if it's being considered from a performance point of view, then Barry's suggestion is much better but inevitably much more expensive.
I would imagine that ZXR400H forks will still need to be re-valved and/or resprung which is going to add to the cost though. _________________ Andy.
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Not trying to push you down the ZX6r route! but Maxton have already re-valved a few sets for RGV's and I would imagine the spring weight etc wouldn't be too different.
I have to say though that I really like the RWU look of the NSR forks and only went for the ZX forks as the RGV already had USD ones. Have you thought about a maxton re-build of the forks and shock? it would probably transform things.
barryj wrote:Are you looking at the ZXR400 because they are a straight swap?
If the ZXR front end bolts straight on without any machining or mods, I will try it. I already have a fully adjustable rear shock from a VFR on the bike, so no probs there. I should look at having Maxton or similar upgrade to the USD's. Thanks Guys
Nothing bolts on without modification unless it's Honda, and even a lot of Honda stuff needs a little modification somewhere. _________________ Andy.
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Yes, I see this. The ZXR front end is on now with the only mod being an adaptor collar to fit the bottom bearing into the NSR frame. Now that's done I have just picked up some ZXR636 forks that very happily fit into the ZXR400 clamps. Whichever way I go, I believe that USD forks are staying on. It changes the whole look of the bike. I like it a LOT!!!
Deon wrote:Yes, I see this. The ZXR front end is on now with the only mod being an adaptor collar to fit the bottom bearing into the NSR frame. Now that's done I have just picked up some ZXR636 forks that very happily fit into the ZXR400 clamps. Whichever way I go, I believe that USD forks are staying on. It changes the whole look of the bike. I like it a LOT!!!
You'll need to enlighten me here !
ZXR H USD's are 40mm
ZX636 USD's are 41mm
Did you just open them up and hammer them in ?
What wheel you running on the ZX forks?
The H yolkes are about 3mm different pitch to the ZX's which is the same as the ZXR L model.
I ask, cause I am in the process of doing a ZX636 conversion too. Just now I have an L & H bottom yolk away getting the pins pressed out, sleeved and set back into the opposite yolk.
The L yolk with H pin will allow me to fit the ZX636 USD's with an '05 wheel and petal discs on using the standard axle pin, spacers (using a digital speedo) and front muddy.
This is getting fitted on a 400 which is about 10Kg less than the 636 so the set-up should be a very good match, however your 250 will be a damn site less in weight so hope your VFR shock can compensate.
I also don't get how the VFR400 forks were soft as again the bike is heavier than the NSR and the sag on them would not of been right with out re-springing them It may be that the initial geometry of the bike was wrong and that's what made you think they were soft either that or your flippin huge
H forks were/are very well made (SP version's are fully adjustable) , modern ones now are fully adjustable as standard and until you leap to Ohlins there is very little improvement over the years.
anyhoo, you've got it all sorted so that is a result _________________ Resistance is futile!
Moriwaki-man wrote:
You'll need to enlighten me here !
ZXR H USD's are 40mm
ZX636 USD's are 41mm
Did you just open them up and hammer them in ?
40mm/41mm is only the stanchion (chrome part) size... the NSR is 41mm too!
The OD of the USD fork legs is often similar across a wide range of makes and models though, around 50~52mm. For example, I have RVF400 clipons on my RS250 forks, and RGV250 forks, heaven forbid, would slot straigt into my HRC triples if I wanted to use them. _________________ Andy.
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Moriwaki-man wrote:Did you just open them up and hammer them in ?
What wheel you running on the ZX forks?
It's a complete ZXR400 front end including wheel, yokes - everything. I will do some measurements on the week-end and post the dimensions when I have the 636 yokes to hand.
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It may be that the initial geometry of the bike was wrong and that's what made you think they were soft either that or your flippin huge 
