XS front end swap

[Rev D]

Wow, that's a lot to take in.
Hmmm, tempted to hit the scrap yard with a tape measure and see what legnths different forks are. I imagine most sport bike front ends are shorter (drmatically), but I reeeeeeally like the idea of how it would look and how much beefer it would be stoping and handling wise.
I know a guy getting his engineering design degree at BCIT, he's into mountain bikes but I wonder if I could con, I mean ask, him to machine some trees for me.....

 

[Rev D]

Anyone know the legnth of a stock xs front end unloaded?

 

[inxs]

- if by unloaded you mean mounted in frame with wheel off the ground...from axle centre to tube top my original is about 760mm

 

[Rev D]

Thanks , yah that's what I meant.

So at 760 mm it is 40mm longer than a gsxr front end. Hmmmmmm, that is only 4 cm, I wonder if that's a huge loss in trail....

Hey Lunatic, if you read this, do you know the trail figures on your bike?

 

[Lunatic]

Sorry, I don't. If someone can tell me how to measure it properly I can check though.

 

[inxs]

- trail

 

[Lunatic]

I'll see what I can do about the measurements.

 

[Sundie]

I'll see what I can do about the measurements.

I bet it's under 2.

 

[Yamaha_chop]

Wow, sorry I didn't jump in on this thread earlier.

The trail on my current sportbike project is at just over 3" so it's fine. Of course I'm also running about 23 degrees of rake, so pretty steep for sure. This is with 2007 GSXR600 forks and stock triples, no offset.

Another thing to remember when switching forks is that if you're looking to use the sportbike wheel with it, you're stepping down from a 19" wheel to a 17" wheel, so you're losing about 1" of ground clearance that way.

 

[Lunatic]

Ok, a little difficult to measure by myself but it looks to be between 3" and 3.5".

 

[Teebs]

As long as that is right, it's not bad at all. I would have expected it to be closer to 2 than 4.

To measure, just follow the angle of neck at center-line to the ground and mark it. Then mark the center of the axle bolt on the ground (on a flat surface like your garage floor, use a square) and measure the distance between the two. Pretty simple.

 

[tms325i]

I have used 2000-2003 GSXR750 USD forks on my cafe/race styled XS. As far as modification to make the forks fit:


Removed about 5mm of the lower neck (The rest is just a bearing swap with the gsxr stem).

Used an aftermarket 6061 top triple (machined about 8-10mm cutout of the stem area to maximize the fork length).

Machined about 1mm off of the lower gsxr lock nut as well to make everything fit nicely.

The triple tree offset for the gsxr is 32mm.

I had a custom front axle made to fit the stock xs hub (17mm) and use the stock speedo gear.

I also used a FZR400 aluminum swingarm with 4 different shock mounts so the rake ranges from 24.5 deg - 26 deg with 12" shocks.

I will check on the rake again but it worked out quite well.

Also picked up well over an inch on the ground clearance.

 

[Rev D]

Once again, wow.

Thanks a ton for check that out you guys, as I think I'm getting a clear picture of what to do, I just wanted to check the trail situation on a shorter front end.

Tms, I saw a xs that had a gsxr front end on it and the owner had lsited the only real mods as shaving the bottome neck cup down so it didn't bind on the lower triple. I think I'll still try to run the stock tire though, getting attached to the spokes! Wait..... would that mean no gsxr brakes and therefore render my swap mostly useless? Hrmmm.....

I may seem a little overly concerned about it being measured out and all but well......this is my first bike, and I'm unable to drive it until I fix it up, so my first trip down the road will be on a chopped up xs!


Thanks again, always thirsty for more info on this!

 

[tms325i]

With the stock front hub I am using a 320mm aprilia sunstar disc/rotor (basically the same as the ducati monster, etc.) with a single brembo 2 piston sliding caliper from a ducati sport classic. Plenty of clearance from the spokes (over 6mm), however, I had to make the caliper mounting bracket.

 

[Rev D]

Hmmm, I'm thinking I might be able to keep the brakes then and just have to machine an axle........as long as the disc will bolt up to the xs rim (seems unlikely). Hrmmm, this is getting complicated....

 

[tms325i]

If anyone needs a custom front axle, etc. contact Cheney Engineering (Jim) http://www.flattrackaccessories.com/

I believe my axle for the gsxr front end was $55. He also laced my excel wheels - he is a Buchanan spoke/rim dealer, prices are fantastic and the work is awesome. Go through him and your wheels will be cheaper.

 

[Rev D]

Thanks for the link Tms!
Might go look at a gsxr front end, I've heard pre 94 is the least headaches.

 

[hooktool]

That's a good link-thanks.

John

 

[Rev D]

Sooooo, how about at 2007 gsxr? Tanyone think that would work too? It's all the wrecker here has...

 

[Rev D]

Soo I used an online trail calculator and it put my trail, using an 07 gsxr front end at 3.43 inches. Not bad, not bad.

Tms, the bearings really just swapped over? I check sizes and they seem like they have a different outside diameter, but yours slid in and fit tight?