1991 to 1992 Kawasaki ZXR750 J Specs and Info

Kawasaki Used Motorcycle Parts

Kawasaki ZXR750 J1 Parts….

Kawasaki ZXR 750 J

The Kawasaki ZXR 750 J (J1 and J2 models) was a 749cc sports bike released in the UK between January 1991 and November 1992.
The ZXR750 J was an updated version of the Kawasaki ZXR750 H1 and H2 models and featured 43mm upside down (USD) forks, lighter, diamond section alloy chassis, new short stroke engine and 38mm CVKD carbs (aka constant velocity carb).

Kawasaki ZXR750J

A little bit about the Kwak ZXR750 J specs………

Model information
Bike model: Kawasaki ZXR 750 J
Years (in the UK): January 1991 to November 1992
Kawasaki model code: ZX750J
Frame number: Started – ZX750J—-

Model and updates…..
ZXR750 J1 (ZX750J1): January 1991 to December 1991. Frame number started: ZX750J-000001-.
Available in green/blue/white or blue gitane.
Cost new (in the UK): £6379

ZXR750 J2 (ZX750J2): January 1992 to November 1992. Frame number started: ZX750J-013901-.
Same as the ZXR750 J1 model but with minor suspension modifications and a softer rear shock.
Available in green/blue/white or wine red
Cost new (in the UK): £6379 (price was reduced to £6249 for a new ‘K’ reg bike)

ZXR 750 J engine

Engine and gearbox
Displacement: 749cc (71 x 47.3mm)
Engine type: In-line four cylinder
Compression: 10.8:1
Power: 100 BHP
Top speed: 143.5 mph
Stroke: 4 Stroke
Oil type: 10w40 Semi synthetic
(ZXR750 J Oil filter kit – Rock Oil / ZXR 750 J Oil filter kit – Silkolene)
Oil filter: Filtrex OIF006 / Hiflo HF303 / Champion F301
Engine oil capacity: 3.2 litres
Valves per cylinder: 4 (16 valves in total)
Cam shafts: Double overhead cams (DOHC)
Cooling system: Rock Oil Water cooled
Cooling system capacity: 2 litres
Clutch: Multi plate wet (oil submerged) hydraulic ‘slipper’ clutch
Gearbox: 6 speed
Gearbox lubrication: From engine (no separate gearbox oil)
Carburetors: 38mm CVKD Carbs
Air filter: Kawasaki part no: 11013-1210
Service kits: Silkolene / Rock Oil

Chain n’ Sprockets
Final drive: Chain (530 pitch chain with 110 links)
Front sprocket teeth: 14
Rear sprocket teeth: 46

ZXR750 J Radiator

Servicing intervals
Oil change: 10,000km (approx 6200 miles) or every 12 months
Cooling system change: Every 24 months (2 years)
Hydraulic brake fluid change: 20,000km (approx 12,400 miles) or every 24 months (2 years)
Fork oil change: 30,000km (approx 18,600 miles) or every 36 months (3 years)
Swing arm pivot and uni-track grease points: Grease every 10,000km (approx 6200 miles) or every 12 months
Other grease points: Grease every 20,000km (approx 12,400 miles) or every 24 months (2 years)

ZXR750 J race brakes

Brakes ‘n wheels
Front brakes: Twin (dual) discs with 4 pot calipers (4 pistons per caliper)
Front disc part numbers: EBC MD4022LS and MD4022RS
Front brake pad part numbers: EBC FA158
Rear brake: Single disc with 2 pot caliper (2 pistons)
Rear disc part number: MD4013
Rear brake pads part number: FA161
Brake systems: Front and rear hydraulic brakes
Front tyre size: 120/70-17 (3 spoke wheel)
Rear tyre size: 180/55-17 (3 spoke wheel)

ZXR750 J Carbs

Suspension stuff….
Front suspension: 43mm USD (upside down) Telescopic Forks
Front fork oil: 445ml of 5w (light weight) fork oil per fork
Rear suspension: Unitrack Monoshock

Weights ‘n measures
Dry weight: 195kg (dry weight)
Wheelbase: 1420mm
Fuel tank capacity: 18 litres
Fuel type: Unleaded petrol

Electrics ‘n stuff
Ignition system: Electronic CDI
Electrical system: 12 volts
Battery: YTX12-BS / CTX12-BS
Spark plugs: NGK CR9E

Other stuff…….
Starter: Electric starter motor
Clutch: Hydraulic operated clutch (no cable)

1991 ZXR 750 J1

Useless stuff…….
Launched in 1991 the Kawasaki ZXR750 J was based on the 1989 to 1990 ZXR 750 H1 and H2 race replica supersports bikes and there are still plenty of these beasties around today.
The ZXR750 was a good bike in it’s day and was used for some racing series and although the ZXR out handled rivals like the GSXR750 and 1100 it was blown away a few years later (along with the FZR’s and GSXR’s) by the Honda Fireblade.

The ZXR750 J was restricted to 100bhp due to an upcoming European 100bhp ban supposedly coming to Europe around the time the J model was launched, but, as with most European laws the BHP ban was scrapped and never came into force.
Although the J model had less BHP then the earlier H models (107bhp) and the later K models (121bhp), the J model had good mid range power due to the lower brake horse power!

Although the ZXR750 J model was based on the earlier H1 and H2 models, unfortunately there aren’t many parts that are interchangeable between the 2 bikes as there were numerous changes between the H and J models (including different forks, engine and bodywork).

Buying advice…….
There are a fair few of these bikes around and you can pick up a good example with MOT for under £1000 privately.
Because of the racing history behind these bikes there are LOADS of ex-racers around (and racing mods like Harrison Billet 6 race calipers can be picked up for these bikes as well!).
These bikes were built to take a knock on the track (with beefed up yokes and spindles etc) so lightly crashed bikes can often easily be repaired.
Obviously, the youngest of these beasts will be around 20 years old now so the bikes do look a bit ‘long in the tooth’ and will have a few age related gremlins and they DON’T handle like more modern counterparts…….
Parts to watch out for when buying…..
Only parts to really check on the ZXR750 is the electrics (alternator, CDI etc) as these can be difficult to source.
The radiators, which due to the racing design of the rad (curved) alot of the ZXR750 radiators were used on other racing bikes and good examples are difficult to get hold of now!
And the upside down forks….
Unfortunately, upside down forks don’t fair well in the UK weather and, unless they’ve been rebuilt and the stanchions replaced they are likely to need work and parts.

Performance mods…….
Apart from the usual Dynojet and K and N filter type stuff there is a relatively simple engine mod if you want a bit more from your ZXR750.
If you put ZX7 pistons in a ZXR750 (it will need a rebore though as of ZX7’s are a couple of mm’s bigger bore) will increase the CC to around 790cc.

Kawasaki ZXR750 J1 Spares….

Sources:
WhiteDogBikes
Bikez ZXR750 J Page
Silkolene.co.uk

Disclaimer: The Kawasaki ZXR750 J specs and information on this page are correct to the best of our knowledge. But the info should NOT be taken as 100% accurate as we can, occasionally make mistakes!

If you think we’ve missed any important info out or have something to add, please feel free to leave a comment below…..

49 thoughts on “1991 to 1992 Kawasaki ZXR750 J Specs and Info”

      1. Hi, Jus bought a J1, having the carbs sorted as its over revving when you open the throttle at stand still. It still has the standard can on it, what increase from 100hp can i expect if i pop a straight through end can on it? many thanks.

        1. Depending on the make and quality of the can, you can get up to a 5% power increase using a race can on most bikes. It should also help to smooth any flat spots in the rev range as well.
          If your getting the carbs sorted, you might want think of getting a Dynojet set fitted and fitting a K&N air filter to the bike as the bike will be set up to run on the standard can, a Dynojet kit and filter will set the bike up better for running on a race can (it’s also advisable as some race systems can cause problems with the exhaust valves if the bikes not set up to run on it?).

    1. All the ZXR750 J’s we’ve had in have been 6 gear (they even show 6 gears on the front sprocket covers)? Not sure where you got you info from, unless Kawasaki made different gearboxes for some continents/areas?

      1. Hi, my info is from my bike ZXR 750 J which stands in my garage
        ;-). I have the version for the europe with 100hp and i have ONLY 5 gears…

        1. What does the frame number on your bike start with (e.g. ZX750—–)?

          I’ve just checked the official Kawasaki service manual we have for the ZXR750 J and it states the bike has 6 gears (both the European and US/Canadian models had 6 gears)?

          1. The frame number start with ZX750J. I know the service manual as well (Haynes)… But when i read that the ZXR has 6 gears i think this is nonsense, my bike has only 5 :-D…

          2. Hmmmmm, very strange!

            We have a genuine Kawasaki service manual (not the Haynes) and it say’s 6 gears. The spec books we have all list 6 gears for both the European and US models (even the race ‘K’ version had 6 gears) and we have dismantled 2 of them and they both had 6 gears?

            I’ve never come across one that has only 5 gears? Are you sure the engine hasn’t been changed in your ZXR?

    2. Wats happening ? I’ve just bought zxr750j(91)import(UK regd 97)n I’ve only 5 gears.Says 6 on casing,engine number zx750jE00.

  1. Well , thanks for respond …I read some said 16/43 …I just not which is right.
    I know them high rpm , it run me 41.6 mpg.

  2. Early comment …the road was dry and no hill.
    I checked the sprocket, it was stamp # 45 on the rear and I don’t the front yet??

  3. Hello. I have just completed the restoration of a 1992 ZXR750R(K2) ZX7R here in Canada. and am trying to confirm the production total for this bike. Can you help me or point me in the direction of someone who can? Thanks in advance. Sincerely, Brent

    1. Sorry, I don’t know how many were manufactured. The only thing I could suggest is possibly try contacting Kawasaki directly and asking or ask a Kawasaki dealer if they have any info on frame numbers (it may be possible to work out approx how many there were based on the frame numbers?)

  4. hello i have a 91 j1 is there any other interchangable parts that will fit this motor to increase hp like you have written the 99 pistons will work with a rebore but can you use late model cams on the j motor or can you run the whole cyclinder head andbarrels or do they not interchange
    thanks for your help

    1. You can use the ZX7R barrel and pistons which should go straight on. As far as I know the cams from later models aren’t interchangeably. Also, the flat slide carbs that were on the ZX7R P models will make go a bit faster (the P models were the race version of the ZX7R at that time).

  5. Hi… Got a 91 and d cards is making the motor unbalance and most times go off… U got any idea where i could get a new card unit and for how much…

  6. HI can you tell me please what is the right hight of fuel level in carburators of a zx7 1991 ? I thank you sincerely.
    MIKE

    1. The float height on a 1991 ZXR750 should be 13mm (+/- 2mm). The height should be the same for the same years ZX-7, ZX-7R. The ZXR750 K1 model (race version of the ZXR750) had a float height of 9mm (+/- 2mm).
      Hope this helps.

  7. I have a fully original ZXR750 J2 in mint condition. It has 6 gears – like all of the ZXR’s do.
    To increase the HP I’ve put the ZX9R motorn in my ZXR750 K2, 41mm flatslides, airtech’s race airbox in carbon, ported, bored to 950cc, lighted crank and other parts. This gives me 157RWHP and together with a fully carbon fiber race fairings, öhlins front back and steering damper and BST carbon wheels this is the most astonishing motorcycle I have ever ridden =)

    It has been my absolute favorite the last 15 years now and I hope I can keep it the next 15 years as well.

    I’m working on a carbon fiber frame to it now to get under 180kg fully fueled up. It is doable.

  8. Good bit of info, I’m building up one of these old girls to replace my ZXR 400 race bike. I’ve ordered a workshop manual but it hasn’t arrived yet and needed to know how much fork,oils to put in. Cheers Pickles.173.

  9. I av zxr750j1 and sometimes wen i turn ignition on the fuel pump clicks continuously for about 10-15secs b4 stopping. Is this normal(doesn’t always do it)or is an early warning of imminent failure ? If so how much are fuel pumps ? Thanks.

    1. No, it’s not normal for your fuel pump to click that much.
      Best bet would be to check the wires from the fuel pump for damage or excessive corrosion. It could also be a fault with the fuel relay?

  10. Thnks 4 reply,appreciated. This is a really helpful site. Also as i like the J1 so much (it feels taught, goes where u point it albeit a bit heavy and only 100bhp,or it did av wen it left Kwak heavy industries)i was wondering hw much a complete pro engine rebuild/renovation costs ? Ne idea ? I’d wanna ride it in and pick it up after everything done.Thnks again n I’ll get wiring etc checked out.

    1. It’s very difficult to say how much a rebuild would cost without actually looking at and striping your engine to find out which parts need replacing (and if you want it back as standard or tuned?).

      The ZXR750’s were used for racing so there are a few ex race mechanics around who worked extensively on the engines (back in the day!), might be worth asking on a Kawasaki few forums to see if you can get in contact with any?

      1. Once again thnks so much and Ur advice is appreciated.An obvious choice 4 more power wud b a zxr9 engine conversion but these engines seem few n far between and wud prob require work/parts ne way ? It’d seem easier just buying a 9 altogether than avin the hassle ?!?! Wen u said back in the day it raised a smile(was it that long ago :-) ).I’ll seek out the forums and mechanics of yesteryear. I love it.Thnks again.

  11. Hi. I am in the middle of a project rebuilding a 1991 ZXR750 J1. Having a problem with an engine fault that could cost more than a second hand engine change. What are the possible engines that would fit into this frame and a rough cost please?

    Many thanks

  12. I was wondering does a 180/55 rear fit on a ZX750-J1 with the rear fender? I was told yes and no from different mechanics, and I know it runs a 180/50, but I kinda want more bang for my buck since most q3s,pilot 3s, and pirelli’s wear fast.

  13. my ZXR 750j1 has an electrical issue.Was Streetfightered b4 I bought it wiv usual aftermarket twin headlights/digital speedo/clip-ons/Arrow pipe.All of a sudden headlights and tail-light stopped working(both front/rear brake light still worked).After fiddling around with block connector from back light that came back on and still works but headlights don,t.I,ve changed headlight bulbs as old ones cheap n nasty and checked wiring for breaks/connections etc to no avail.The handlebar switch wen all was relatively ok still only used to put the tail-light on wen switch moved to side-lights then obviously headlights wud come on at next flick of switch.The high/low beam worked too.As of now the bike fires up fine/indicators/horn/kill switch/brake/tail-light works but no headlights.All fuses ok.Surely it has to be a bad connection ? Thnks in advance

    1. I know ur a zxr750j site forum but I av zx9r(2000) and wondered if u cud help ?I av a rumbling noise coming from wat seems to be clutch(noise quietens a bit wen u pull clutch lever in)on tickover.It vibrates a bit through seat too.You can hear it quiet clearly from inside clutch casing(ear to it).Bike has 26,000mls and has had shims,compression test,carbs balanced,oil changed professionally at 24,000mls.Engine oil looks a little milky on top(through window)but bike has been sat a while.Engages gear ok without any major clunks.Was told new camchain was fitted by competent,experienced mechanic who races Kwaks(but no paperwork proof-there is for shims etc).Any ideas as I,ve heard of head gasket issues,cogs,water pump,alternator drivechain prob.Thanks in advance.

      1. If the waters milky it could be a blown head gasket or leaking water pump. Rumbling noise is probably a bearing either gone or on it’s way out (if water has leaked into the oil, this could be why the bearing has failed?).

        1. Thanks for reply,appreciated so much.Am I looking at a complete engine strip,although it’s hard to pinpoint(rumbling sounds like inside clutch casing)is it possibly a clutch issue and if head gasket is shot what’s cost roughly(professional work)? Thanks again.

          1. Sorry, I don’t know the cost mainly because it depends on what extra parts and work are required (e.g. does the head need skimming and if something caused the head gasket to fail that may need fixing/replacing).

            Will probably be fairly costly as it does require removing the engine and partly stripping it down (you’ll need someone good doing it so it’s put back together correctly!).

  14. Hi, I have a ZXR 750R K1, the switch on top of the flatslides has two wires black & green which disappear into the loom. The Haynes manual doesn’t mention it and I think it is shown on the circuit diagram as the Throttle Switch. What does it do ?
    The bike is being a pig to start and runs on choke for ages before I dare run it without. I use it for classic events.

    I have cleaned the flatslides twice, checked tappets, none tight. Plugs and coils are fine, the pump seems okay with a good flow. Compression is about 130psi, I know it could be better ! It will fire with Easi-start but not on petrol ??

    Any suggestions ?

    Thanks Barry

    1. You compression should be around 180 psi,
      what main jet size,needle number and slot,piolet jet size and air cleaner are you running?

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