R6 (-99) front forks on xj900(-83)

So I got me a striped down xj900 and a friend of mine are willing to donate a set of front forks from his desembled R6. Sounds good considering the look of the forks on my xj900. Although, how much headache will this result in? Are they in any way plug and play in a way that it can be done without custom triples or use of any other heavy machinery?

Br
Robert

 

The XJ900 steering head/stem dimensions are't exactly the same as on the XJ650, but the process is.
xj650-to-r6-front-end-conversion-step-by-step.40332

The forks will likely be under-sprung. The xj900 is a tad heavier than an R6 (around 150 pounds heavier).

 

Amazing.
Thank you. This will work using my 1999 R1 forks also. I see you are using a bit more fancy ones

 

I have a set of forks if you need it or would rather keep the stock configuration. For that matter I have a 900 in a box almost

 

Thanks. I live in Norway so would be a bit easier to take the R1 forks Think I will try to put them on the bike using k-moe recipe always fun to learn new stuff.
Hopefully with the skilful people at this forum it will be doable.

 

I got this out of All balls racing. Do this mean the forks will fit as they are?

 

Are you planning to keep the XJ900 front rim or use the R6 rim? The easy way out is to install the entire R6 forks, wheel and brakes.
This however mates a 3.50" wide front rim mated with a 2.50" rear. Some have installed 900 Diversion rear wheels but this is not plug & play.
Running a wide radial tire up front and a skinny bias ply in the rear is not a good idea.

 

I have the same era R1 forks mine are 2000 with Race Tech .9kgm springs for my '82 XJ750. my bike has a listed weight of 524# and the R1/R6 about 100# less OEM springs for the R1/R6 is .73kgm if I recall correctly? In my opinion the front end is the best mod to make on virtually any older bike, better braking, better damping, often lighter weight, stiffer, and better tire selection (radials) You can buy a set of USD forks for about the same as emulators and springs however the XJ bikes are heavy and my spring upgrade was $90.00 for the springs. Two cents.
Cheers, 50gary

 

Thanx for all the info.
I have the R6 forks (I sees that I wrote R1, sorry bout that) in the garage and will order the bearings. I will keep the xj front wheel. Possible to use the R6 breaks with them? Or will that just be stupid?

 

The rotor spacing is critical, the width of the R6 forks and brake caliper mounts must be on the same center as your XJ parts.
Cheers, 50gary

 

Ok. Anything that can be fixed otherwise?

 

Interesting mod, please let us know how it went when it's on!

 

Everything can be fixed with the right skills, materials and tools, but once again this shows that fork swaps are not as trivial as some people believe...

 

No fun when it's easy Then everyone would be riding smoooth looking bikes.

Any idea what needs to be done?

 

You haven't made clear what your intentions for this bike are Mysk but since you're considering a fork swap I'm assuming it will not have the XJ900 fairing and instruments. You'll need to compare the steering stem of the stock 900 to the R6 to see if you can simply install the R6 fork crowns with a bearing swap, with any luck it might just fit being all Yamaha. Then you'll need to find out if the R6 clip-ons foul the fuel tank at full lock, you might need mods to limit the steering lock to lock.
Now you need to figure out a way to mount your instruments to the R6 top crown.
Then you need to see if the forks are shorter, perhaps install stiffer springs also.
Adapting the 900 wheel to the R6 forks, compare the axles, are they the same diameter?
In all likelihood the forks are wider spaced which will require custom wheel spacers, your speedo drive likely won't fit. Magnetic pick-ups with electronic speedos are available today.
You will probably need custom adapters to mount whatever calipers to the forks to line up with the rotors on the 900 wheel.
You'll need custom mounts for the fender.

 

I am amazed over all the knowledge at this forum. Thank you so much. The bike will be a gift for my newly born baby girl when she is old enough to ride it. So time is on my side and knowledge about the bike are something I will pass on to her.
Again thank you!

 

If you're determined and have that much time then hey give it a go. It only really makes sense to swap the entire front end. you could start by buying a set of R6 yokes/triple trees to see if the stem fitsinto the 900 heastock , if not then you might be able to use the stem from the XJ900 Often these are pressed in and you might get lucky if the 900 stem can be pressed out of it's yoke and pressed into R6. If not you could be in line for a custom made stem, but since it's round its something a local shop can run up. after that it's relatively plain sailing with adapters spacers etc.. and remember that spindle diameters can sometime be adapted to fit using different sized wheel bearings...

 

Sounds good.
I see now that a front wheel with breaks are about 250 dollars so maybe it's better to go with that. Not as fun but hey

 

agreed, however @Mysk then has an unbalanced bike with a wide radial upfront and a skinny bias in the rear.
I like the streetfighter look of an old UJM with modern radial tires like @LarryMc has accomplished with his 550.
Chain driven bikes are a good starting point, the shaft driven XJ's are a bigger challenge.
A wider 17" rim can only be sourced using a wire wheel Virago hub and lacing it up with custom spokes or a 900 Diversion wheel with some machining.
Then you still have the issue of clearing the swing arm on the driveshaft side. A 180/55-17 will never fit, maybe a 150/60-17 with slight swing arm mod???

This video illustrates the 17" conversion of a monoshock Virago, should be similar to an XJ.

 

That isn't my writeup, nor did I come up with the methodology.

 

Ooooo....I might have a need for that.

 

Thank u. Unbalanced as in looking all wierd or as in crappy riding experience?

 

I read that the handling could be a bit tricky with a wider front tire. Any possibility to fit a wider rim in the back. At least as wide to make the handling better.

 

The thing is, wider tires are no advantage unless the frame geometry (side to side) allows more ground clearance for leaning over further.
All a wider tire does is allow for a larger radius before you encounter the sidewall (excluding drag tires). You don't get more grip (compounds do that, and there are several modern compound tires available in stock sizes). You don't get a larger contact patch.

 

Not sure I understood all of that
How bad would the handling be if I deside to put a R6 front wheel on and keep the stock rear one. Is it a big no no? I see other bikes with that set up.

 

Steering will be slower.
I see people driving without their seatbelt all the time; doesn't mean that it's a good idea.
Accident avoidance is the motorcyclist's seatbelt. Slower steering is a not-good thing IMO.

You are also likely to run into a situation where you can't find the tire you want in both sizes.

 

I would never mix tires, radial in front, bias in rear. I would never have offset wheels front to rear. I would never have a smaller width tire in rear. Slower steering with the wider R6 forks would (in my guess) still be quicker than the stock geometry of the XJ bikes due to much greater rake angle of the stock XJ . The shorter forks without the leading axle and smaller diameter wheel/tire of the R6 will likely de-rake the chassis quite bit yielding quicker steering. I might be tempted to try a bias tire 110/70/17" on the 3.5" wide R6 wheel? With a 130 bias in back. Shaft driven bikes are more difficult to modify for sure.
Cheers, 50gary

 

Update!

So I got the forks mounted with the help of All Balls racing (Amazing people over there, just amazing) Next up will be to mount the R6 breaks that just arrived.
I decided to run the full front from the R6 with rims and wheels

 

Bearings is the easy part. You will have to worry more about length of steering stem.

 

I'm pretty sure the OP already tackled that part. See the writeup I linked on the first page for how.

 

Yeah. Got it all done with the forks. Not the easiest task but got some propper help The original one fitted

 

Come on then - let's see the finished article!

 

Yes will do