rear wheel conversion.
The GPz900R has an 18" rear, and I am finding it hard to get
decent sticky rubber.
By this I mean Z-rated.
The rear wheel size is 18" diameter and 3.5" wide.
I had a Michelin MACADAM 150/70/ZR18 fitted.
No-one had these anymore. Not instore nor on the Web.
I just could not find an 18" tyre to suit nowdays.
I even spoke directly with Yokohama, Dunlop, and Michelin.
So, even though I am happy with the 18" and the 150 size
(the original GPz900R before A7 had a 130/18 rear), I decided
to do a rear wheel conversion to a 17".
This seems to be a commonly adopted size now, and of course
means plenty of available tyre choice.
Firstly to investigate the options.
How big is enough ?
Can I do just the wheel, or do I need a swingarm too ?
How costly ? And how much do I want to spend ?
And can I do the work at home ?
So, Check out the Web.
There doesn't seem to be any information that I can find
regarding 17" rear wheel conversions specific to my GPz900R.
Comments but no details.
Has nobody done this before ?
Doesn't anybody want to share information ?
Or is this the realm of the mechanic only ?
Well, after a bit of running around and speaking to the right
people, racers and wreckers.
I decided to settle on a pretty straight forward conversion.
It might not be perfect (yet) but it will suit me.
It is simple.
And I will share.
In the years of 1990/1991/1992 the Kawasaki ZZR600 came
out with a rear wheel that is 17"(dia) x 4.5"(wide).
And also most importantly it has the exact same axle diameter,
I think 17mm (I might need to confirm this), as the GPz900R.
The later model ZZR600 has a bigger diameter axle - known
as the 'big axle' ZZR600 wheel.
You can check the year of the wheel manufacture by looking
at the embossed markings on one of the 3 spokes.
On the ZZR600 wheel, the markings are on the right hand side.
The year of manufacture is on the spoke that has the "Kawasaki"
"MADE IN JAPAN" printed on it.
You will see a circle with a split number in it.
In my case it has 9|2 in the circle. ie: 1992.
The wheel is also a 3 spoke Enkei in exactly the same style,
apart from a very minor cosmetic difference with the spoke
hole shape in the hub being round instead of elongated.
So, I have sourced one.
A complete one. (axle, brake disc, cush drive,
sprocket carrier, sprocket, even a pretty good tyre)
Basically pulled out of a 'wrecking' bike.
Cost $500 Aud.
That seemed about right. But the trick is to get the whole deal.
The disc is a 230mm ZZR600 unit.
You will need to get yourself a ZZR1100 unit which is the
required 250mm, then you can use the original GPz900R
brake caliper and original mount - once modified.
- The GPz900R 250mm disk is a 6 bolt pattern and the
ZZR1100 250mm disk is a 4 bolt pattern.
- Note that the A7 has a 250mm rear disk in my example.
- The A1-A6 may be a 270mm (or 280mm) so you may need
to fiddle with the mounting bracket to align the caliper.
I paid about $50 for a very usable ZZR1100 rear disk.
You may wish to try the lower mounted ZZR600 single piston
rear brake caliper setup for the 230mm disc, but I wanted to
keep it simple, with sort of the original look, and also use
what I already had.
If so, buy the ZZR600 brake caliper and make sure you get
the axle spacer caliper mount.
Oh, and while you are sourcing parts, get yourself a Kawasaki
GTR1000 centre stand.
It fits exactly. Using the original centre stand mounting bolt.
It is wider at the base by about the same amount you are
increasing your tyre width. I assume the GTR had a wider tyre.
You will see that it is longer too.
I can get the bike up on the centre stand, but it really should be
shortened to cater for the lower 17" tyre profile. It's hard to lift.
Maybe shorten the base of the stand by about 1.5" and reweld
the slide plates. I have not done this yet.
And I had to prevent the stand from fully raising by about 1" to
give better tolerance between the stand centre bar and the tyre.
Next thing is to measure everything up.
as the 'big axle' ZZR600 wheel.
You can check the year of the wheel manufacture by looking
at the embossed markings on one of the 3 spokes.
On the ZZR600 wheel, the markings are on the right hand side.
The year of manufacture is on the spoke that has the "Kawasaki"
"MADE IN JAPAN" printed on it.
You will see a circle with a split number in it.
In my case it has 9|2 in the circle. ie: 1992.
 |
| Check out the Manufacture Date of the Wheel. |
The wheel is also a 3 spoke Enkei in exactly the same style,
apart from a very minor cosmetic difference with the spoke
hole shape in the hub being round instead of elongated.
So, I have sourced one.
A complete one. (axle, brake disc, cush drive,
sprocket carrier, sprocket, even a pretty good tyre)
Basically pulled out of a 'wrecking' bike.
Cost $500 Aud.
That seemed about right. But the trick is to get the whole deal.
 |
| The Old and The New. |
The disc is a 230mm ZZR600 unit.
You will need to get yourself a ZZR1100 unit which is the
required 250mm, then you can use the original GPz900R
brake caliper and original mount - once modified.
- The GPz900R 250mm disk is a 6 bolt pattern and the
ZZR1100 250mm disk is a 4 bolt pattern.
- Note that the A7 has a 250mm rear disk in my example.
- The A1-A6 may be a 270mm (or 280mm) so you may need
to fiddle with the mounting bracket to align the caliper.
I paid about $50 for a very usable ZZR1100 rear disk.
You may wish to try the lower mounted ZZR600 single piston
rear brake caliper setup for the 230mm disc, but I wanted to
keep it simple, with sort of the original look, and also use
what I already had.
If so, buy the ZZR600 brake caliper and make sure you get
the axle spacer caliper mount.
Oh, and while you are sourcing parts, get yourself a Kawasaki
GTR1000 centre stand.
It fits exactly. Using the original centre stand mounting bolt.
It is wider at the base by about the same amount you are
increasing your tyre width. I assume the GTR had a wider tyre.
You will see that it is longer too.
I can get the bike up on the centre stand, but it really should be
shortened to cater for the lower 17" tyre profile. It's hard to lift.
Maybe shorten the base of the stand by about 1.5" and reweld
the slide plates. I have not done this yet.
And I had to prevent the stand from fully raising by about 1" to
give better tolerance between the stand centre bar and the tyre.
Next thing is to measure everything up.
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