FJ1100 fork conversion

[bikerphil]

Yep. that HF small lathe would be nice. They're having a big sale now too.

I'm doin' some damping rod drilling mods on my forks at the moment. Another experiment... I'll post some pics later.

[SteadyT120]

Hi guys been reading your thread with interest. I have a 1984 FJ1100 and found the standard fork springs far too soft. A set of aftermarket Progressive springs really sharpened it up. If you are going to all the trouble of fitting FJ forks to your XS I would recommend replacing the springs too.
My XS11 is set up as a sidecar outfit and has leading link suspension so I have never experienced the standard XS forks. Cheers Steady

[crazy steve]

Ok, another update (a day late, but I got sidetracked yesterday). Here's some pretty close (+/- 1/8") measurements comparing distances from the axle centerline to the top of the fork neck, depending on whether you put a spacer on the top of the FJ stem or the bottom and if you're going to use clip-on bars or conventional bars. If going with clip-ons, I'm figuring 1" of tube protruding above the top tree.

Stock forks: 30.5"

FJ forks, spacer at top: Clip-ons, 28.5", standard bars 29.5". With clip-ons, you're losing 2" of front end height.

FJ forks, spacer at bottom: add 1" to the above measurements.

So by using standard bars and the bottom spacer I can retain full front end height, but there's two caveats; one, I have to either fabricate/buy/modify some risers for the bars, and this also requires 'cheating' the fork taper into the lower tree by about 5/8". Plus come up with the lower spacer and new steering stops. But I've found a way....

A spacer under the bearing isn't a big deal, but the steering stops are. And I don't like not having full 'clamping force' on the tubes with that taper cheated into the lower clamp, although I don't think this would cause any problems. My solution? Luckily, I bought two full sets of forks/trees, so...

Press the stems out of both FJ lower trees. Take one FJ stem, build up/remachine the bottom bearing surface so the bearing can be higher on the stem. Next, take one FJ lower tree and 'surface' the bottom of it just until it's flat. Flip it over, machine off the stops and bearing boss. Cut in the 'recess' for the stem retaining clip. This one is done. Now, take the other tree, and machine the bottom of until you have your 'spacer' thickness (measured at the stem boss). Machine the top of the clamps down flush with the tree. Press the modified FJ stem into both lower trees with the 'bottoms' of each facing each other and there it is; full clamping on the tubes, your bearing spacer and the stops. The lower tree is going to look a bit bulky, but no worries about strength. I know, I know, a picture is worth etc, so I'll take pics and post them, along with actual dimensions, as this progresses.

One question for Phil; was there any issues with rerouting the wiring harnesses that passed under the forks? Do you think there would be an issue if it had to go 1" lower?

One last observation; if you want to reuse the FJ clip-on bars and retain full height, it may be possible to put the bars under the top tree. Phil could answer this better than me. May put them a bit low, so I wonder if could you swap some parts with the XJ bars (aren't they similar?) to get them higher? Food for thought...

'78E original owner

[bikerphil]

One question for Phil; was there any issues with rerouting the wiring harnesses that passed under the forks? Do you think there would be an issue if it had to go 1" lower?

There's no issue with that harness. You should be able to go 1" lower I think. The brake line junction and the wire bracket for the harness are even a direct bolt up. The lower headlight adjuster needs to be fabricated, but it was pretty easy.

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.

[crazy steve]

Ok, I've got all the major machine work done on the lower tree(s). Seeing how I have yet to manage to post the actual pics here, I think I'll just post a link to the album....






Of course, the pics are in back-asswards, so starting from the 'end' you have:

Before and after of the FJ stem. The top one is stock, the lower as modified. I've built-up/remachined the area where the bearing presses on 7/8" higher. I also altered the top to use the XS stem nut, but that's entirely optional.

The 'bottoms' of the FJ trees. These will actually face each other when assembled. Basically, I just cut enought off to give a flat surface and remove the rolled edge; more on this further down. The 'tubes' sticking up are homemade 'tooling'.

The 'tops' of the FJ trees. These are actually the new 'top' and 'bottom' when assembled. The bottom tree has had the stops and bearing boss milled off, and the recess cut for the stem c-clip. The top tree had the top part of the tube clamps milled off as there won't be anything to clamp to on the tube due to the taper. Finished thickness of the trees (measured at the stem hole) are .920" for the bottom tree and 1.08" for the top tree for an assembled thickness of 2". I milled about .100" off the bottom of both trees; you need to check this as you go.

The 'assembled' tree. At this point, you could press the stem back in, knock the sharp edges off and install it. I'm going to 'blend'/polish this further for appearance, so I have a lot of hours of hand labor in front of me yet.

More later as I get further along.

'78E original owner

[bikerphil]

Damn, that's pretty slick, glad I didn't try that one with my hack saw.

[snowdog51]

fj fork

amazing you all took this basic simple mod and really ran with it i had no idea it would go this far i made the bottom spacer cause i thought i need ed all the height i could get but the fjxs1100g is happy to be lower would be nice to up grade the fork to 88 or newer get the monoblock calipers
by the way the springs are totally unusable ps springs do the job



by the way i have a complete fj fork with 7/8 bar risers gives about 3 inches up 2 inches closer stock standard bars are good for me and i have the worlds shortest arms anyway if anyone wants it pm with an offer

time to do the swing arm if you all haven't done the r1 mono shock thats an awesome mod i'll post some pics of the sa

[snowdog51]

swing arm

try this

[snowdog51]

fjxs1100g

photo of bike

[WMarshy]

Check it.

I bought some FJ1200 forks! They are nice looking too. Im going with the clip-on handle bars and a FJ front break master cylinder, maybe hydraulic clutch too! More to come later.

[bikerphil]

Nice! You got them for a good price there. Good luck with your build. Are you going to put them on your F or your SF?

[WMarshy]

They will go on my F, eventually I will do a frame off rebuild of the SF and might get another pair for it in the future. Of course I need to get a titled frame to build on for the SF, or go through the International Title Service. At some point I want to make a "super-XS" so I need to decide which one that will be, Im thinking of using the E that my Dad has in storage.

[crazy steve]

The more the merrier!

I'm waiting on my new axle and front calipers to show up from ebay. I bought HD 4-pot units as I know they're not very 'deep' and I won't have any issues with wheel clearance. Plus I think they'll be fairly easy to mount. Not as much braking power as some of the late sport bikes, but an improvement nonetheless. As I went in a somewhat different direction from Phil, you'll have choices on the mods!

I finished up the mods on the fork sliders, the fork internals, and the fork caps today. I'm going to go with RaceTech emulators; I already had a spare pair for 39mm Harley forks and with just minor machine work these fit right into the dampers (they're a PITA to tune, but oh well...). For springs, I'm going with Progressive front springs and see if I can keep that 'boulevard' ride rather than the 'racier' straight-rate that Phil used.

As per my usual over-the-top methods, I'm massaging everything until it's as pretty as I can make it; I'm going to start polishing parts tomorrow....

More pics and details soon.

'78E original owner

[WMarshy]

The more the merrier!

I'm waiting on my new axle and front calipers to show up from ebay. I bought HD 4-pot units as I know they're not very 'deep' and I won't have any issues with wheel clearance. Plus I think they'll be fairly easy to mount. Not as much braking power as some of the late sport bikes, but an improvement nonetheless. As I went in a somewhat different direction from Phil, you'll have choices on the mods!

I finished up the mods on the fork sliders, the fork internals, and the fork caps today. I'm going to go with RaceTech emulators; I already had a spare pair for 39mm Harley forks and with just minor machine work these fit right into the dampers (they're a PITA to tune, but oh well...). For springs, I'm going with Progressive front springs and see if I can keep that 'boulevard' ride rather than the 'racier' straight-rate that Phil used.

As per my usual over-the-top methods, I'm massaging everything until it's as pretty as I can make it; I'm going to start polishing parts tomorrow....

More pics and details soon.

'78E original owner

COOL Keep us informed about the breaks. Maybe by the time I have my forks all mod'ed you'll have posted the tech tip for the HD breaks and I will be ready to assemble mine with them. I want to try the FJ clip-on's and if I dont like them will go back to the stock bars or equivalent. Im definitely going with the spacer under the neck but not a double bottom clamp like you lol. Im just not too keen on the look. Im thinking about using the straight wount springs vs. progressive, in either case the emulator is a must. What are you doing to the fork caps, is there something Im forgetting about? I will end up having to re-read this whole thread when I get mine.

PS. I think Phil still has the progressive springs in, not straight wound... Phil, what is that front break master cylinder off??? I LIKE IT

[bikerphil]

Phil, what is that front break master cylinder off??? I LIKE IT

It's the XS11 stock unit with shiny aluminum where the original metal info. plate was.

Right now, I'm running Sonic straight wound springs 0.90kg/mm.