FJ1100 fork conversion

[cywelchjr]

If the lower FJ tree is aluminum and the stem is steel... how exactly do you weld them to prevent the pressed in XS stem from backing out?

I've got my FJ trees apart and it looks like there is enough room on the fork to move both lower and upper trees closer together to make up for the spacer Phill used... Anyone know what the distance is between the XS upper and lower trees? Also, which direction does the stem come out of the FJ lower? Looks like there is a c-clip but I can't get to it, the lower bearing doesn't want to move...

Might end up machining my own stem to fit...

I think he means you need a good strong high lip welded onto the XS stem to catch on the FJ tree when you press it on so it doesn't pull through when you tighten it up. As you tighten things up the stem it going to try and pull out the top of the frame tube, and the only thing that would stop it would be some sort of lip on the bottom that won't let it pull through the bottom tree, which it sounds like would be a problem without welding a strong bead onto the bottom of the stem.

[snowdog51]

fj conversion

when i first did this, i made it a simple ,cheap , and easy to do .
i'm blown away how it's change from that, all that work for a very average fork.



keep the shiny side up

[bikerphil]

After 20K miles, front end holding up beautifully, much more solid feel than my Special with stock forks. Running high bars now...

[crazy steve]

If the lower FJ tree is aluminum and the stem is steel... how exactly do you weld them to prevent the pressed in XS stem from backing out?

I've got my FJ trees apart and it looks like there is enough room on the fork to move both lower and upper trees closer together to make up for the spacer Phil used... Anyone know what the distance is between the XS upper and lower trees? Also, which direction does the stem come out of the FJ lower? Looks like there is a c-clip but I can't get to it, the lower bearing doesn't want to move...

Might end up machining my own stem to fit...

The stock trees are about 7.75" apart at the neck. One problem you'll run into by moving them closer together is that will limit where you can position the fork tubes due to that 'taper' machined into them between the trees. The best way to do this IMO is to weld/remachine the FJ stem shorter rather than trying to use the XS stem, which may prove to be too short. Between that taper and the 'upside down' clamps on the lower FJ tree, it makes it a bit tough to get the fork length you might want. You'll also end up with quite a bit of fork tube sticking above the top tree and that may cause problems fitting handlebars. The FJ stem presses out the bottom of the tree by the way...

If you have access to machine tools, IMO the best solution would be to make a spacer to press onto the stem (making the FJ stem the same 'effective' length as the XS stem without shortening it). The challenge here is incorporating the steering stops into the spacer. This will require welding/remachining the FJ stem lower bearing area so the bearing will still be tight. This is similar to what I did; this gives you the most options in positioning the forks for final height.

Phil went the way he did because that's the 'no machining' way; any other method will require some machine work.

[WMarshy]

Got the lower race off the stem, some heat and a heavy hammer drove'r home. Still trying to get the stem out of the lower tree. Been trying to pound on the bottom side of the tree and force the stem through the bottom of the tree. Got some movement but not much, let me know if there's an easier way. Thanks.

[bikerphil]

Wade, you'll probably need a hydraulic press to get that sucker out. I tried taking the stem out of an FZR lower TT (same c-clip set-up) that I was going to originally use and no way I could get it out.

[WMarshy]

The stock trees are about 7.75" apart at the neck. One problem you'll run into by moving them closer together is that will limit where you can position the fork tubes due to that 'taper' machined into them between the trees. The best way to do this IMO is to weld/remachine the FJ stem shorter rather than trying to use the XS stem, which may prove to be too short. Between that taper and the 'upside down' clamps on the lower FJ tree, it makes it a bit tough to get the fork length you might want. You'll also end up with quite a bit of fork tube sticking above the top tree and that may cause problems fitting handlebars. The FJ stem presses out the bottom of the tree by the way...

If you have access to machine tools, IMO the best solution would be to make a spacer to press onto the stem (making the FJ stem the same 'effective' length as the XS stem without shortening it). The challenge here is incorporating the steering stops into the spacer. This will require welding/remachining the FJ stem lower bearing area so the bearing will still be tight. This is similar to what I did; this gives you the most options in positioning the forks for final height.

Phil went the way he did because that's the 'no machining' way; any other method will require some machine work.

Thanks for the tips Phil and Steve. I guess my plan is going to include modifying the FJ stem to accomidate my needs. I plan to move the lower tree up as far as reasonably possible, minimizing the size of the spacer that Phill used for the lower bearing. I still think I will need a spacer but I might be able to retain the stock ride height that Phil lost. It might prove easier to maching a custom stem rather then weld and re-machine the old one. I see the original FJ stem is tapered on the ID and I dont want to thin the stem wall too much by moving the upper bearing race down... hmmm, might have access to a CNC as long as the stem is 20mm or less in OD. Seems like it was at least 24mm at the largest end...

[crazy steve]

...I still think I will need a spacer but I might be able to retain the stock ride height that Phil lost...

That's the main issue; retaining ride height. Phil lost about 1.5" of height the way he did his swap, all due to the limitations caused by the fork tube taper and not using a spacer at the bottom of the stem. In order to retain stock height, you need to move the lower tree down with a spacer on the stem, as well as 'flipping' the lower tree over. Something like this....
[IMG][/IMG]
(If you go to post #95, that details what I did) What's important to note here is those 'left over' tube clamps on the top half of my 'finished' tree don't fully clamp on the straight part of the tube. If you don't 'flip' the lower tree, you'll still find that taper going into the clamp if you want stock ride height.

I spent a lot of time messing with this, trying to find the easiest combo to keep stock ride height, and this is what I came up with. You wouldn't need a second lower tree to do this, but you do need a spacer and a 'flipped' lower tree to get a 'full' clamp on the tube at the lower tree. The critical stem measurement you're looking for is 7.5" from the bearing shoulder at the lower tree to the top of the threads for the stem locknuts, same as the XS stem.

I've sent you a PM....

[bikerphil]

If you choose to go the easy way as I did, the loss of ride height doesn't really come into play unless you are running some sort of fairing. Use custom heavier springs correct for your weight and you shouldn't have any problem. Running the handlebar setup instead of clip-on's, I was able to drop the forks down in the TT's some more raising the ride height a bit. Lower center of gravity is a good thing.

[WMarshy]

...As for the clip-on's below the upper TT, I guess that would work, but the headlight ears would have to be cut down about 3/4" to be out of the way.

The stock FJ clip-on bars will not work like that. The post that comes off the clamp part interferes with the fork tube and will not allow you to slide them down the tube. I can take a picture later... That got me thinking if there are aftermarket clip-ons that will allow that configuration. Newer sport bikes have the clip-ons under the upper TT, so I'm going to look online to see if there are and that might work for the 41mm forks. Otherwise I might have to make my own..

[bikerphil]

There are tons of 41MM clip-on's out there ranging from $50-$150 after doing a quick search. I guess it's not possible to trim the extra metal off the stock FJ clip-on's so they'll fit. Another option would be to drill the top TT for regular bars.

[WMarshy]

Any tips on disassembling the fork cartridge? This is my first time, the seals look good so I don't want to ruin them... and I want to know the proper way. Im going to check the FJ site but, if you already have a "how to" link please let me know! Thanks.

[bikerphil]

If you need the service manual you can check ebscohost. Careful not to snap off the small indexing screw on the back of the fork lower. You'll need a 27MM holding tool for the damper rod. 27MM hex for the fork caps too. 10MM allen on an impact is helpful. The upper bushing and seal will come out easily as you remove the upper stanchion unlike the XS fork.

[WMarshy]

If you need the service manual you can check ebscohost. Careful not to snap off the small indexing screw on the back of the fork lower. You'll need a 27MM holding tool for the damper rod. 27MM hex for the fork caps too. 10MM allen on an impact is helpful. The upper bushing and seal will come out easily as you remove the upper stanchion unlike the XS fork.

Looks like this is where I stop... I torqued off the bottom 10 mm cap screw without removing that anti rotation screw in the back of the fork. Read your post then removed the little guy, now its bent slightly. Just glad it didn't snap off! Better wait to get the manual and I need a 27 mm allen... perfect, I get to go buy tools.

[bikerphil]

You will probably have to use a 27MM nut on a threaded rod with a split pin thru the center or weld it to an old extention. An allen that large may be hard to find. Lowe's or Ace will have them, 1 1/16" will work and be much cheaper. Just straighten out that bent screw or make a new one. Next time take the screw all the way out first.