FRONT WHEEL SWAP
When back in 1990 I traded my FJ 1100 and tested my 1st 1200 3CV, I noticed at once a great loss in agility, due to 1200´s 17 inch front wheel. Even dropping the yokes 1 cm (sliding fork tubes in the yokes up) I couldn't get the same feeling that with the 16 inch front wheel. Even today, riding my own 1986 model, the 16" front tyre gets a fantastic light handling, with a superb flickability on tight roads.
The 1200 front rim is a 3", not a usual 3,5". Fitting a 120/60/17 instead of the original 120/70/17 is a wrong way: not only the bike dropped in thigh bends but there were not confidence at all at the front wheel when braking, and with much faster front tyre wear.
On STD rims, 3x17 front FJ1200 88 on proper mount is 110/70/17, like it is exposed at the tyres section on this website. Even in a closed track, like the picture taken on May 2022 at Calafat Circuit, the front works fantastically : agility is improved without loss in stability or control on the front tyre. And the tyre has a proper life, with no bad wear, like 120 tyres on 3" rim.
Yamaha FZR 1000 Génesis 1987-1988 front rim
Anyway the easiest solution is to install a front wheel from a Yamaha FZR 1000 Genesis, 87-88 model. It is 3,5" wide and it is a bolt on item, and a modern 120/70/17 tyre fits right, without deforming its carcass. The difference in front feeling is awesome!. More stability when braking and much more feeling and confidence at the front wheel in all kinds of riding.
The original bearings are a couple of 15x42x13 6302 2RS2. It is recomemded fitting new and these are not expensive.
Yamaha FZR 1000 Exup 1989-1992 front rim, 17 mm axle
Exup OE bearings are 17x40x12, so to maintain the FJ original 15 axle, spacer and speedo the are 2 ways, or make wider 1 mm the rim bearing beds or fit 2 15x40x12 bearings, not 13, OE FJ bearing deep measure.
Next problem comes from the rim inner bushing: Exup rim needs 2 mm longer than FJ 15 mm inner bushing that has to be made. Or the bike will perform horrible thrilling shimmies when the axle and bearings start flexing when riding hard (tested. Not good).
So the easiest way is drilling the fork vases to 17 mm, using the Exup axle with its nut, Exup right spacer and speedo. The Exup axle must be cut a little because it is too long.
The original 298 mm discs fit straight on the Exup rim.
In Spain are forbidden brake calliper adapters to fit proper one in order to mount bigger than standard discs, so to fit the above rims with 298 mm discs it is necessary to change the front fork vases from a 3CV model . Proper callipers and discs are needed too.
Fork tubes & suspension springs are the same. You can see the conversion at the pic in one of my FJs.
It is recommended slid the fork tubes up 1 cm to gain agility.
GSXR SACS REAR WHEEL SWAP
It can be used any SACS 750 90 to 94 or 1100 91-92 rear rim. You need the complete rear wheel assy, with all the OE spacers, sprocket, rear disc and brake calliper. And 2 big 20mm. flats, that fit to each side of the axel, between the spacers and the swing arm. Ah!, and a longer rear brake hose.
It fits straight on, with a perfect rear sprocket alignment (laser measured). And it is a massive 3kg weight ligther than the EXUP rim!. Only be sure that the rear sprocket comes from a GSXR 750 90-94, because it is 530 chain size, vs. 1100´s 532 size. I keep the 17/40 front and rear even although the total drive is a little shorter than the OE, because of the shorter rear wheel diameter. I got the 40 th sprocket special-made by JT reference PN: JT 0816 CD40
A good idea is to replace the bearings in our purchased second-hand rim when installed. Bearing codes are 6204 RS (2 in the rim) & 6305 RS (1 in the sprocket carrier)
The only drawback is that you have to find a point to fix the rear brake calliper torque arm. As far as I know, there are 2 solutions:
1.- Fix a hand made torque arm to the main stand right fixing point (but you lost the main stand facility) or at one left rear footpeg support, drilling the hole and using a longer screw. The big problem is that it is a fixed point and dont move, so it limits the suspension movement.
2.- Dismantling the swing arm and built a point at the front where to fix a hand made torque arm. See the upper left photo and the photo at the right. Mine is professional welded on
The FZR 1000 torque arm fits near straight on. Only the brake calliper screw hole side must be enlarged to support the GSXR OE calliper attached screw. You can re-use the FJ front arm screw to fix it at the swing arm and the GSXR calliper OE arm screw at the back
The gearing gets longer around 3 km/h. With the 170/60, the wheel diameter is 1 cm shorter, not too much, and the gearing goes down 3 km/h. You could go back your OE gearing simply fitting a 1 tooth less rear sprocket.
And presto!. the chain is laser aligned. Job done!
It is adviced fitting a shorter rear suspension linkages to compensate the shorter rear wheel diameter. An easy task. This is not possible on the FJ first series and I recommend to purchase an YSS shock with adjustable length.
You must fit a 180/55 tyre (it fits) because of modern 170 tyres are designed to fit 5" rims, not 5,5", like this one. 170 fit flat, will waste faster, and for an expert rider is easy to pass the edge of the tyre in open roads, which is dangerous beause of the sliding (even fun).
With the new rims and the 170 the bike feels simply like a modern superbike: rigid, solid, planted and nimble, all at the same time, due to the modern tyres. Comparatively, it feels like a FJR1300, only more nimble and shorter. (the FJR 1300 feels like a FJ with an ice-trolley at the rear)
EXUP 1990-1994 RIM SWAP (my friend J. Carlos signs the followig text. You can see his face when he viewed first time my bike rear rim). He has adapted the mod to his new 3CV model too
conversion is not as difficult as it could be from a first view.
I remember that it was a brain-teaser when I got the wheel from
ebay. I thought that I was unable to follow others Fj owners
instructions like Barry Edwards’s (http://www.fjmods.btinternet.co.uk/Wheels.htm).
But once meditated and thought over it I had to do it because I already had the wheel. So I went for it making some changes on Barry instructions in the process
1 year from being a proud FJ owner, and with a lot of
holes in my pockets …due
to my brainless fitting of all improvements that I could and with a few frustrations and a couple of
completely-nutter errors, I had fitted all the good mods that
you could dream in my FJ: GSXR 1000 brake master cilinder,R1
callipers, metallic hoses all around, new OE fork springs (3XW Hagon
springs are too hard for my taste, these are one of my errors
K&N air filter, Hagon shock (another of my errors) and FZR 1000 front rim.
Then, plenty of envy to see Alf's FJ rim and after our travel to Portugal where I had a lot of juicy dreams about the Alf's FJ BIG tyre, I decided to try my last FJ owner frontier: the rear rim swap. With the rim in my hands I started the job with the Barry ideas and with Raul Coll instructions, another FJ owner... and my own measures, that I got to find a couple of details to solve the equation
necessary mods are as follows:
1.- Cush drive hub/sprocket carrier lugs reduced 7 mm (photos
1, 2,3) and Cush drive rubbers 7 mm shaved (photo 4)
2.- 7 mm shaved from the inner sprocket carrier, its
spacer and the inner metal o-ring (photo 5)
3.- Remove 2,5 mm of the Cush drive hub outer diameter (photo 6)
4.- Remove 10 mm from the swing arm face of the FJ
mounting bracket (photo 7)
5.- Shave 1 mm from the right FJ collar spacer, the
one between the sprocket carrier and the swing arm (photo 8)
I cut the cushdrive rubbers with a handsaw and I kept the little
studs, even although it is not necessary maintain them (photos
9,10). In fact, you only shave 9 mm because you have to
sum the little stop at the inner rubber (photo9)
must force a little bit the caliper bracket, but it fits.
you take detailed measures, all that work is to shave 10 mm by
each side to fit the rim straight in the swingarm.
With all done, I fitted the rim and checked that the sprocket carrier weaved. It was due to a cushdrive rubber that was badly trimmed. Take the rubbers to a professional and don't use a handsaw like me!
The chain and the brake disc are perfectly aligned. The difference with the new rim fitted is awesome!. The bike feels more stable on straight line and more flickable on curvy roads. The perfect mode!
My bike has evolved from a little antiquated bike to a true modern superbike that it has nothing to envy on more modern hardware. With a planted and firm feel on the motorway and armchair comfort you can do 600 km diary like myself & Alf past summer. The brakes are superb, the handling is fantastic on tight curves, with a grunt ultra-reliable engine and with fantastic mechanical accessibility, far superior on today bikes
…you can't avoid feel in love with!!!!!!!
Update August 2.017: RPM sell an 6,5 mm. offset front sprocket. Fitting it with this Exup swap make unnecessary the rear sprocket carrier modification, just being only the rear brake adapt the job to perform. The chain would be correct inline without any other mod only fitting this sprocket
FZR 1000 87-88 REAR RIM SWAP
The appropriate tyre size is 160/60/18, with a wide selection of modern radial tyres. I think this is the best solution to the FJ 1100 & 1200 86-87 series becuase the rear wheel diameter is in fact a little longer than original, there are no necessity to compensate the geometry, like with the 17" conversion.
Only the rim, 2 bearings an 1 oil seal are needed to make the conversion, machining an inner spacer like is specified at the graphics and modifying a couple of parts as is described, all of them original FJ items..
YZF 600 THUNDERCAT REAR RIM 1.997-2.006 (créditos a Phill, from Fjowners.com)
The complete YZF600 rear wheel, including sprocket carrier, caliper mounting bracket, rotor, and the 2 wheel spacers is needed.
You may/will also need to take 3mm off the sprocket carrier face, where the sprocket sits ,so the chain is inline, but just buy a rear FJ1200 sprocket that has a 2 or 3 mm recessed step in it. Most sprockets have a step one side and are flat the other. Simply, mount it reversed.
I think this is the simplest swap of all. The Thundercat rim is 5" wide, so the tyre size recommended is 170/60/17. A 180 mm. tyre would physically fit, but most of the modern 180 tyres are designed for 5,5" wide rims, so It would be forced and I can't recommended it.
With a 170 the bike go perfect and it doesn't need a 180 in open road, so the rim size would not be a handicap, to my knowledge.