ZX10r Fork Swap onto Virago Help

[jthompson9134]

Hey everyone, I just bought a 1983 XV750 and am trying to retrofit the forks from a Kawasaki ZX10r. All balls bearing doesn't list this conversion on their website, but I've seen that Cognito Moto has a conversion steering stem kit with bearings for a custom stem to fit the forks from a ZX6r onto the neck of the virago. I've measured the diameter of the stem from my ZX10r forks and it's about 35mm. If the stem from Cognito moto is the same diameter at the base, couldn't I theoretically use this stem with bearing and press it into the lower tree? I've been trying to find out the diameter of the stock stem from the ZX6r but haven't found anything definitive. I assume the threads at the top are the same, and if they're not it wouldn't be hard to source new nuts to secure it. I would just rather spend half the money on a prefabbed stem instead of having to spend the extra cash on getting it "custom fit" from cognito since I'm a broke college kid! Anything helps!

Here's the link to the cognito moto stem: https://cognitomoto.com/products/zx-6r-fork-on-yamaha-xv750-xj750-virago-frame-conversion-stem

 

[irk miller]

Are the stems the same length? A shorter stem will move the clamping location for your fork legs. If they're tapered, or stepped, you won't be able to use the ZX6r stem with the ZX10r front end. What is the ZX10r stem length compared to the Virago? You may need spacers to make it work. Also, the All Balls kits are just taking existing bearings and races and putting them together for conversion kits. You can measure your ZX10r stem and your Virago neck tube and make your own kit, if the lengths jive.

 

[jthompson9134]

After taking all of the old bearings off and measuring everything, it looks like the stem from my ZX10r front has a diameter of 35mm at the top and the bottom, while the neck of my virago has a diameter of 48mm. I don't think anyone really makes any bearings that are that thin, so it looks like I'm going to have to have a new stem machined to size (probably 30mm stem). It looks like the stem and the triple on the virago are welded together, which is a bummer since I was hoping to try and fit that into the new lower tree and have a bushing to fit it correctly.

 

[Streetfighterkz]

If you do some looking and measuring, you may only need a small lower bushing. When I swapped a set of Zx11 triples onto my Gpz, I was able to cut the Zx stem flush, insert the Gpz stem in what was left of the old stem and weld it up. The Zx stem was steel and so was the Gpz stem. Maybe having a small steel bushing with the ID of the Virago stem but the OD and profile of the Zx10 would be easier than turning up a completely new stem.

Later, Doug

 

[Streetfighterkz]

Oh yeah, the Gpz stem was welded in from the factory. Throw up a pic of yours and maybe we can help further.

Later, Doug

 

[irk miller]

I did a similar thing to put a TL1000r front end on my BMW R100/7, but machined the two pieces of stem to be press fit, then welded them up.

 

[jthompson9134]

Here is the old stem vs the new stem. The old stem is 30mm OD while the new is 35mm OD with an ID of 15mm. It looks as well like the old stem is steel and the new is machined aluminum. That being said, if I ground out the old weld and tried to press them both out, I could just fit a bushing and weld it onto the old to fit to size? Since it's steel I don't think I would need to worry about the stress on the joint at the weld or the fit. Do you think this will work? I'll try it either way and see what I come up with! If this works I'll probably save 3 weeks of time from the machinist and $200.

 

[chickenStripCharlie]

as the original stem is steel it should be easy to rework the bottom part to fit the aluminum clamp ... however what is the length? You dont want to fit it in the new, thicker, clamp and run out of room if you are not able to slide the lower triple up the tubes enough.

 

[jthompson9134]

I ended up grinding the old weld off and removing the old stem from the lower trees. After having the new stem pressed out, I found out that it had a small step in it. I was going to try to fit a bushing in there to weld it all together and press it in, but I don't have the tools for proper tolerancing, and machine shops around me didn't want to waste their time unless I paid at least $500. So off to cognito moto it goes! Thanks for all the tips and pointers guys