XJ650 to R6 Front End Conversion Step by Step

Hey guys, I have been lurking on here for a while now with minimal activity so I thought I would share my latest success with you.

To start out I am turning my 1980 XJ650 into a cafe racer type of machine. While not your average cafe bike I have seen some pretty nice ones. So on to the pictures and how I did mine.

First off you need to source a front end to use. I went with an ebay special, its a 2006 Yamaha R6 front end. I got it complete minus the levers and the front wheel and tire. If I am correct the '03-'12 stems should all be the same with only minor differences in the '05 braking system.

Ok moving forward.... this is what I received in the mail.


After taking both the 650 and the R6 stems apart I measured the bearing surfaces. The top bearing surface for the R6 stem in 30mm while the lower bearing surface is 31mm. Once that was established I moved back to the neck of the 650 to find that both the upper and lower bearing race diameters were 48mm.

From there I went to Allballsracing.com to see if they had a direct conversion kit. They did not. While they offered the 30mm I.D. X 48mm O.D. bearing(PN: 99-3506-5) they do not make a 31mm I.D. version.

So armed with that I went back to the R6 stem and measured more and determined that there was enough meat at the lower bearing surface to actually turn down the 31mm bearing surface to the required 30mm diameter needed.

With that settled I had to determine the height of the bearings that I need the clear the lower portion of the neck and still fit the stem through the top. So the lower bearing seat is about 19mm up into the neck, with that I went back to Allballsracing.com and saw that they offer the needed bearing diameters in 3 different thicknesses, 15mm, 14mm and 12mm. So since the distance needed to clear the neck was 19mm, I decided to get the 15mm thick bearing and just make a spacer for the lower bearing. The dimensions of the needed spacer are as follows, 48mm O.D. X 30mm I.D X 4mm thick.

After that I measured the top to be at about 11mm, so naturally the 12mm bearing(PN:99-3515-5) was needed there.

So back to more pictures....

Her you can see the 4mm spacer, seal, and the bearing (PN: 99-3506-5) on the lower bearing surface of the R6 stem.


With that ready for the bike it was time to install the female portion in the 650. (PN:99-3506-5)


With that in the top female section was installed. (PN:99-3515-5)


Once they are installed it is time to slap it all together right? Wrong!!! With the first complete test fit it was clear that that the hole for the upper dust cover would need to be bigger and the thickness would need a trim as well. also needing attention was the booger weld on the neck. So after cleaning that up and trimming the cover it went together without a hitch.


Checking the lower clearance yielded more space than I first imagined, plenty of clearance and no need to grind down the neck.


With both the lower and upper triple in place it was time for a fitting of the forks, wheel and the clipons to see if they cleared the tank.


I still need to modify the turning stops a bit but I should be able to get it pretty close to stock steering with the clipons flared out just a bit from the stock R6 positions. Clearance is a bit tight but it will be all good once the new stop is welded in.



And finally step back to admire... (just the stock light sitting in there)


For those that hate reading here is a "Quick and Dirty Recap"
'03-'12 R6 Front end complete assembly
Turn lower R6 stem bearing surface to 30mm
Make 4mm spacer for lower bearing
Lower bearing PN:99-3506-5
Upper bearing PN:99-3515-5
Trim upper dust cover, grind weld
Install all parts and enjoy.

V/R
Chris

 

sa-weeeeet! cant wait to see more!!

 

NICE write-up (with pics even) and work! Those bars do look close...

skillet

 

Awesome how-to, detailed and concise.

 

Looks nice. Did you notice if this ended up raising or lowering the front end significantly?

 

Nice! This is the kind of work and Mods that inspire me to want to pickup another XJ and do something like this.

 

Those handlebars really do look dangerously unusable.

Looks good, though. Great work.

 

Thanks everyone, once I get it a bit further along I will probably start a build blog. As for the clip on to tank clearance, I think it is just the picture, I have been on numerous sports bikes that have way worse clearance issues than this thing.

In regards to the lowering issue, I think it lowed it about 2 inches. I am also running a 750 18" rear tire to get the look im after so it will have a slight rake forward, it will also help clear the exhaust that I will be running under the bike (2 into 2 exiting just in front of the rear wheel)

 

That RC51 is a dream bike of mine

 

What type of exhaust are ya' talkin' about? "Store bought" or fab your own?

skillet
btw lookin' for ideas

 

I like what I'm seeing here. My questions are... Does this leave you with rims that no longer match? If you're still using the seca rims how are the brakes aligning for you?

If you have time can you narrate that a bit and post more pics about how that's going for you?

 

For the exhaust, I will be doing a custom setup, two 12" reverse cones under the center of the bike ending just before the rear tire.

For the wheels yea they will be mismatched. I am using the 750 rear wheel and the r6 front wheel. I will be making aluminum insets that will fill the slots in the 750 wheel to make it look like large spokes rather than just thin slivers. Once they are both repainted the proper color I feel it you should not be able to tell that much of a difference front to rear. I would love to put full spoke wheel on it front and rear though.

I will be starting a build blog soon once I get a bit of time from flight school stuff.

-Chris

 

What is the difference in axle diameters between the XJ and the R6?

 

huge.

nice swap though.

it looks like you cant turn the wheel much? how about moving the tank back a bit?

 

The wheel movement is about 5* less than my roommates RC51. Not a huge difference but yea parking lots may be a challenge but everyday riding should be fine. Moving the tank back would require me moving the forward mounts, and the rear mount. Trying to get it all lined up perfectly again would be a pain in the ass, not really feeling like playing with that. If it is to much of a problem once test riding comes around, I will just pound the tank in a touch with a rubber hammer.

 

Looks great want to do this to my 750 someday.

 

5 deg less doesnt sound that bad.. if it tuns out tight you can always just keep it in mind and steer away from small spots

anyways it looks fffffffin cool!

 

Hi

Thank you for this info.
I would like to know if there are heavy vibrations from the front while riding
fast?
It looks very good but is it safe?
I will appritiare any comment..

 

Yoni, I have not ridden it yet, still waiting on a few more parts. Hopefully it will be rideable in a few weeks, Ill let ya know then. I am also planning on installing a steering stabilizer as well to take care of any slight vibrations.

 

The pics are gone. Any chance to reupload them?