I am rebuilding my '79 V50 as quite a modified bike. I am looking at options in case my preferred option of a front end does not work. What other forks may fit that are either USD or larger diameter that use the standard stem of my V50? Thanks.
Let me use not related set of yokes as an example for you. Most of modern bikes tend to use the sort of yoke at the bottom of this picture. This means, your turning radius will be limited, but also it may mean at full lock you may hit fuel tank with the fork. Just keep it in mind when choosing more modern forks.
Actually, I found a picture when I tried to fit sort of Ducati Monster front end to Imola 350. Actually, thats single-disc Cagiva River. I am quite sure V50’s headstock is shorter than Imola, but on the other hand you would need to fit it with proper tapered bearing cup, what will extend the total length of what you need to poke through top yoke. I did it, but I had to machine the bottom yoke stem.
the yoke i am hoping to use is this one. it does have some angle to it and not totally flat/straight. i haven’t tried the tank on yet as i am still not certain i can use these forks if i cannot get the brake calipers to fit.
as it is today without the brake calipers i need to mock up fitment…they’re on their way to me…this is how we are looking with the front end.
That’s all OK, now you must find out what is the offset , I mean, disc-caliper relation. I can only imagine modern, powerful brakes will tend to keep disc very close to leg, to cancel/minimise twisting forces during braking, while here I can see quite a massive gap. I also bet your fork would work with at least 260, but rather 285-up disc, even 320. So, you will need to choose whether you relocate the caliper towards Guzzi disc, or maybe leave the caliper in place, fitting matching disc with hub-disc adapter. I went that way once with success. It is fortunate in case you use four pot caliper, that you may find matching master cylinder quite easy. Tell us something about the fork and what caliper it uses normally. What I want to say, you may easily “downgrade” to one 285+ disc, as with four pot caliper braking will be still more efficient than with factory layout.
After a quick mess about with the ZXR caliper I have used some washers to work out what spacers I might need for the discs, if that is the right way to go about it. I have 4.8mm worth so far and tomorrow I will try adding one more and see if that helps with centering the caliper on the V50 disc…more pics to follow. I still might need to make an adapter of some sort for the caliper bolts to the fork bottoms.
The “only” problem I now can see, is how are you going to push caliper closer to the axle, to let it cover the disc with pads. At the moment it doesn’t look very convincing.
I am expecting to have to fashion an adapter to get the disc/pad set up correctly. I am hopeful but accept that this may not work which is the case with most special builds. An alternative might be a slimmer caliper perhaps.
We may have here a “visual” issue, when you want above all to keep both wheels from same parish, as we say. Simplest solution would be to use the wheel dedicated to this fork - job done. But if you want to stay “visually” true, mind, Guzzi disc has quite a substantial offset, while most of modern ones are more or less flat. To make a “shim” in between Guzzi hub and chosen disc, you will need to know Guzzi disc/hub PCD and number of holes(six, I think), and the same for new disc. Then, if they are quite close, it may make some problems as you need to drill both sets of holes in one billet. Still doable, but you see, matching wheel solves everything in one go. Your choice. And your expense!
Where are you based, BTW? Interesting topic, worth to talk about with a beer in the hand. And - I did it couple of times, with more or less success.
Ideally I would have liked to use the wheel that goes with the forks, however it is too wide in relation to the Guzzi rear wheel. Off the top of my head the ZXR front tyre width is 120 and the Guzzi rear wheel is 110, hence needing to use the Guzzi front wheel.
I am going to add another washer to the stack today, hopefully which, fingers crossed, will push the disc out sufficiently to meet the caliper. Otherwise my plan for this front end will come to an end.
I am based in Lincoln. I use a guy from ebay of all things to make spacers etc so may ask him to do some for the disc once I have got dimensions to know for certain whether this is doable.
The beefiest tyre I fitted to the rear was 5.10, which is 120+. Then you could probably find 110 fitting well to your front jap rim. Anyway, I am pretty sure I had 120 tyres on the rear. They cannot be “tall”, like 120/100, but 120/90 will fit.
That’s interesting…I will double check the tyre sizes today. The internet says that a ZXR front tyre is 120/70/17. I will get in touch with a tyre fitters and ask if it could go down to 110 at the front. Using a ZXR wheel would eliminate all problems. Worst case scenario would be front and rear tyre sizes the same.
so the tyres on my guzzi are 90/90/18 front and100/90/18. i wonder if i can go down to a 110 on the ZXR front but i imagine that the sidewall height would have to go down to 60? i would like some differential between front and rear tyre widths as i suspect that the handling would be less nimble with 120 front and rear or even 110 front and rear. the other point to note is that the guzzi wheels/tyres are 18" whereas the ZXR front wheel/tyre is 17" to complicate matters.
Guzzi designed 16" front wheels in mid-80’s, apparently along with the general trends of those times. Lario, V35III - I had one with 16" front and 18" rear. Hated the look and fitted longer ratio gearbox with 16" rear to balance it:)
I had a FireBlade that had a god awful 16" front wheel with 17" rear. Someone is pointing me in the direction of V50 or V65C rear wheel which was wider than the non custom bikes.
But you have to be aware, there is a big chance their swingarm was already an inch longer - and this gives that bit of space towards the gearbox, where fatter tyre can also become taller. With V50II you got a swingarm shortest of three. There’s no problem with swapping the swingarms, you know, but you then need to find matching longer driveshaft, then adapt UJ, as V50 has 10 splines and others use 12 splines, then rear mudguard looks a bit not in the right place - and shocks, they need to be longer:) So… In three days time I am gonna see my V50, I’ll check what tyre is there.
thank you for checking what you have. i have been made aware of the spline issue, longer v50c drive shaft needed, etc…too big a headache. think i will go to a 110 if i can and accept that the front tyre will likely have to be a 110 also. cheers
Yeah, just checked, C models use longest swingarm and accept 130/90 tyre, and the rim is 16" 2.5 wide, vs 2.15 in standard bike.
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the only other option would be to shoe horn a v65c engine, gearbox, swingarm, etc into the v50 frame perhaps.