Kawasaki Ninja ZX Forum banner

DUB's Bitza ZXR750 J1/K1

24K views 63 replies 18 participants last post by  THEDON 
#1 · (Edited)
DUB's ZXR750 J1 rebuild.

Hi all from Perth, Western Australia. I've been having a look around at dedicated Kawasaki forums and yours looks pretty cool.

I've been mocking up parts I've accumulated over the years to build a custom ZXR750, or as you guys call them a ZX7R. Going to do things like lower the front suspension drag-bike style, slightly lengthen and widen the rear end to something like a 240-300 rear tyre. Maybe put a later model rear subframe on it.

I'm missing a top triple clamp and motor/box and this is where I was thinking maybe a ZX9 motor might go well in this frame. I haven't seen anyone do it but was wondering if anyone knows of a similar conversion, or if they even fit? There's been a couple of times I've seen a loose reference to using the 900 motor but I haven't seen any threads specifically for this yet. The frame is a ZX7RR K1. I was going to use this frame on my old J1 (after I polished it) but as it was never registered (race frame, never even had sidestand bolt holes) the rego authorities here wouldn't let me register it. Something stupid about it not having enough VIN numbers! Might as well make a mind blowing custom/show bike then!

A few pics>>




I've dropped the forks through the bottom clamp to get it sitting where I want it, but was just going to reset the springs to suit once it was loaded with motor etc.


Any advice would be very much appreciated. Cheers!
 
See less See more
4
#2 ·
#5 ·
Yeah it's the stock colour the J1 came with. Liked it from the moment I first saw one when I pulled in the driveway of the guy selling the first bike I ever bought :)

The frame was the OEM gloss black but thinking an anodized silver or brushed black might be the way to go this time.

Was thinking of upgrading the forks to a much later model so I can fit radial Brembo brakes. These forks have a little rust and pitting in the hard chrome and the front ends now-a-days just make the older fronts feel ancient.

Really like the 96 ZX7R front fender too, it suits the bike so much better than the original.
 
#9 ·
Well it's all happening now!

Got a lead on a '92 ZXR750 that had been sitting for at least 4 years in a blokes shed collecting dust. Got in touch and came up with a complete bike he had intended to make into a track bike but just never got around to it. Laid down the cash then and there and had it home in an hour, and stripped in another 2. Carbs look clean, a little sediment in the bowls. Should be only needing a carby clean spray and a balance.

Battery is stuffed as you'd expect, so new one tomorrow.

Will degrease, wash, scrub, detail the chassis/motor in the morning, and get new coolant, oil, filter, brake fluids, spark plugs, fork seals/oil too.

Pull all the little brackets off and send them off to the powdercoater to be sandblasted and refreshed.

Hopefully have it running and heading towards rego by the arvo, then let all the fun stuff begin :D

Should have taken a 'before' stripping shot but it just looks like another stock ZXR with a custom paint job on it.







 
#11 · (Edited)
She runs :)

Gave it a good degrease this morning and had a better look at what was in need of attention. Left a nice oil slick heading out the driveway, especially after nearly 9 cans of degreaser.



Found one very heavily welded piston block. Never seen anything like this before. Looked like it had been cracked, welded, machined and re-installed so continued on.



Continued on and changed the oil, filter, new battery, replaced fuel lines and filter, re-installed carbs and tank. Started it up :) In need of a good tune, revs ok but short on fuel. Might replace the fuel pump tomorrow with a spare and see what happens. Getting a fast clicking sound from this pump every now and then. Symptom of a failing pump?

Electric fan works, stays under 1/3 temp, but carbs are all over the place.

Found an oil leak coming out the clutch slave area. Looks like there should be some kind of seal where the clutch rod passes through the motor and over to the clutch itself. Anyone confirm this?



Lowered the front about 1 3/4" and put a ZX7R front fender on it. Just mocking it all up at the moment. Then once it's all running complete I'll tear it back down and paint/polish/powdercoat/detail :)



 
#12 ·
She runs :)



Found an oil leak coming out the clutch slave area. Looks like there should be some kind of seal where the clutch rod passes through the motor and over to the clutch itself. Anyone confirm this?

Yes, you are missing the clutch rod oil seal... its about $10
 
#13 ·
Looks like who ever fixed that cracked block knew what they were doing... thats some nice tig work and not for the faint of heart to repair that
 
#16 ·
As I've mentioned before I would like to widen up the rear end of this ZXR for a fatter look. Ultimately a stupid wide rear like a 300 for shows would be great, but that's a long term engineering project. In the mean time I'm going to see what I can achieve with later model Kawasaki stuff.

Took an original 5 1/2" rim off to the wreckers to see what a late model 6" ZX7R rim looked like next to it, and came away with a stella deal on a whole swingarm/wheel assembly! Ultimately this is a far better set-up as it has the wider rim, wider swingarm to suit, and the rear caliper mounting is a lot cleaner too as it does away with the caliper torque arm. Something I really wanted to do as I want to put in a shorter exhaust muffler in the forward area the arm mounts to. The big question being does the swingarm fit in the frame?






Short answer, YES!!!:D (apologies in advance if this is a well known mod. It's all new to me!) I trial fitted it all up to my spare K1 frame with no issues at all.







I had to use the older swingarm main bolt, but the internal sleeve on the new swingarm is the same diametre, and the outer spacers are the exact same width as the old swingarm too. Looking at the shock it looks the same, but will have to mount it up to confirm this. I might try a later ZX7R shock to suit, but I'll have to move the battery to allow clearance for the gas cylinder.

Next is polishing and painting :D:D:D

Also found some Harris Engineering billet 6 pot calipers. Should add just the right amount of bling to the front end I reckon :)



 
#17 ·
That swingarm looks great on there. Very nice factory mod. Is it the same length? How about the pickup point for the rear shock? My only concern would be throwing the rake and trail too far off, but it might be dead nuts.
 
#19 ·
Cheers, I was pretty stoked to see it all fitting in there too.

I'll be disassembling it to send off to the polishers shortly, but before I do I'll put the two swingarms together and see how they compare and report it back here.

The rear shock pickup looks dead-on. Don't think there'll be any issues there either.
 
#23 ·
Some more progress today>>

Shortened adjustable levers arrived.



Pulled the '03 ZX7R swingarm apart and sent it off for paint and polishing along with the rim.

Here is the original and the new swingarm next to each other>>









The shock linkage is identical, along with the main pivot point width/diameter too. Comes with the rear caliper slide welded into the inside leg for a cleaner look (no caliper torque arm needed) as well as no rear hugger and a revised chain guard.

Looking at ordering a new radiator along with some other new parts too. Once it's registered it'll all be coming apart for the full chassis polish and paint, as well as a shed-load of ProBolts and detailed other things. Chasing a carb rebuild kit at the moment. Got some Aluminate solution to soak them in to bring them up to concourse condition in the mean time. Really enjoying ripping into a bike build again :)
 
#24 ·
Nice project.

..so now you can register the bike if you use the frame from the 2nd bike you bought, right?


The car is nice too. If I had to drive on the right side of the car man that would just mess me up bad. :crackup
 
#25 ·
Going to just go ahead with the second bike and mod that instead. Use the race frame and spare bits for refurbishment and mock-ups for things like the 300 rear end etc.

Driving on the opposite side of the road isn't that hard. Went to Germany a couple of years ago and hit the 'bahn in a manual Audi. Went all over the country and it was sweet.
 
#28 ·
Reassembled the carbs tonight after soaking and cleaning them. The Aluminate solution I soaked them in formed a kind of gel-like paste on the slides which took ages to clean off. Didn't really leave anything made of mild steel looking too good either. Might give it a soak in some Evaporust to clean the surface rust off those parts only. Only really the choke slide and the sync screw brackets.



Ordered a big box of parts from Babbits today too, including a brand new radiator and a whole bunch of other new/shiny bits and pieces. Looking forward to that arriving :D
 
#29 ·
Got a sweet delivery today when this big box arrived from Babbitts. Right within the estimated delivery time too, so was most impressed. This was even after the order was put on hold because some parts weren't available anymore, or on back-order. I told them to just send what was available and here it all is.



Assorted seals, filters, gasket, as well as the carb mounts that I recently found out were leaking. Added these into the order while it was on hold so had a little win there as no extra charge for freight.





Brand new radiator :) Even when everything else is redone (paint/powder-coating etc) a manky radiator always stands out to me. Was just happy to be able to still source a new one.





Can't wait to get the frame back and start putting it all together.
 
#30 ·
BASTARD!!!... i am looking for a new RAD!!!
 
#34 ·
wow look great might have to add a rad to mine list too cuz that looks way better then mine lol
 
#35 · (Edited)
Got it rego'd on Monday. Let the fun begin!!! :clap

I think I'm getting pretty close with the carb tuning. It's starting a lot better cold and also smooth for most of the rev range, however when the weather is warmer its stuttering in the higher rev range. Rode it on a cold night and it revved clean all the way through the rev range although seemed down on power still. Pulled the plugs on getting home and they all look like they're burning even. Opinions?





Stock main and pilot jets, mixture screws out 2 turns, must be stock needles as there's no sign of any washers on them or notches as mentioned in other threads on carb tuning. Float heights set to 13.5mm. Usually returns to idle when revved but seems a tad slow to get back there (is this a sign of lean mixture screw setting?) but will sometimes idle high at the lights until I reduce the idle adjustment and it drops to 1100 again. I suspect this might be a sync issue but I have yet to sync as don't have a tool to do this yet. Anyone confirm it might be the cause of the sometimes high idle?
 
#36 · (Edited)
Hi
Your ZXR looks to be coming along nicely, Do you have anymore pics with the new swingarm on?
I have a 94 ZXR 750 L that I am doing a bit of a streetfighter build with & I have just changed the forks over to ZX7 using the ZX7 6 piston calipers, A rather easy conversion & the original ZXR front wheel & axle is now used on the ZX7 forks

I am looking into changing the swingarm over to ZX7 also like you have, Im guessing /hoping the chain & rear sprocket line up nicely, Do you have any pics from the rear showing this?

Not sure of the jetting for the earlier models but I pasted this from my build thread>

"CARBY JETTING

I have read that taking the pilot jets up from #38 to #40 & the main jets from 170 (outers) & 190 (inners) to 180 & 200 is pretty much a standard upgrade to make sure it is not running too lean which I think is the case, The same with just about any stock bike usually

I did not want to (Or refuse to) pay $10 - almost $20 as I was quoted for a single jet here in OZ & I am happy to wait for some jets to arrive from any part of the world (preferably USA) so I have been searching around for pilot & main jets that are reasonably priced, We all know that something so tiny is not worth what we pay here in Australia, We pay too much for way too many things here

With other bikes I have shopped around before & found various jets for around $5ea (+ postage) but did a little bit better again this time

I have ordered a total of 8 genuine Keihin jets ( 4x #40 N242-25B pilot jets & 2x 180 & 2x 200 99101-393 main jets ) all for just under $40 incl postage which is pretty damn good considering I would be paying around $80 for the same thing here"

Cheap jets here>
http://www.power-barn.com/servlet/the-Intake-and-Fuel-cln-Jetting/s/1/Categories

I am going to give the CR9EK plugs a try next time I need a set>
The spark should be more exposed & run horizontal rather than vertical & more hidden from the chamber behind the plug tip


This is my L before I did the fork conversion + the tank & tail have been repainted gloss black

(more pics here too> http://s1250.photobucket.com/albums/hh540/NINJAINOZ/ZXR750 FIGHTER BUILD/#!cpZZ1QQtppZZ24 )

 
#37 · (Edited)
Thanks for the info on the jets and plugs mate. I'll be looking at mucking around with all the jets more once I have the custom exhaust sorted. It's going to be located in the belly pan and just kick out the side in front of the tyre. Lots of custom mandrel bends to buy and tig welding to do yet though.

I've just got the new swingarm, frame, and wheels back from the polisher. I have to remove all the headstock bearing shells as well as any other bits of steel etc (anything that's not aluminium) before dropping it all off to the anodizers. It's getting all clear anodized so I don't have to keep polishing it all the time and can just enjoy it more once it's back on the road. If I can get hold of a full ZX7R front end with the 6 pot calipers I'll be doing that conversion as well. Did you need the later model triple clamps or can you just use the originally supplied ones?
 
#38 ·
I would like to put a muffler down under the motor too, Would make it all look a bit tidier but it may be hard to keep it quiet?

I bought a set of forks with the lower triple clamp , You can use your original ZXR top clamp, The lower section of the ZX7 forks are larger so the later lower triple clamp is all you need & just use the stock bearings which are the same for ZXR 750 & ZX7

All my goodies>
http://s1250.photobucket.com/albums/hh540/NINJAINOZ/ZXR750 FIGHTER BUILD/

I sold the old forks & calipers for just a bit less than I paid for the ZX7 forks & calipers so it was a cheap upgrade>

 
#39 ·
I just received a ZX7RR (Race model) shock for $42US around $90 including postage from the USA





I got hold of a ZX7 rear caliper, Master cylinder & swingarm bracket mount, I gave the caliper a tidy up with some black paint & fitted some new EBC FA161HH pads I had laying round so it is almost ready for the conversion when I get a ZX7 swingarm

How are you going getting yours all back together? How much did the anodizing set you back?
 
#41 ·
Holy shit that's cheap! Where do I get one for myself?!!! I take it you're modifying the battery box cos there's no way that will fit in there without doing some cutting to the plastics.

I have been a bit slack as of late. Trying to track down a ZX7R front end but also I have to remove the bearing shells and other steel bits from the frame/swingarm before I can send it off for powdercoating. The process is great for ally, but destroys anything that's not ally. Have been quoted around $50 for the frame, and similar for the swingarm. The polishing of both those parts cost WAAAYY more than that. Including the wheels and painting the spokes it was over a grand.

Will let you know what I pay for the anodizing when it's done. Hopefully soon.
 
#42 ·
Haven't done that but the airbox was modded when I got it. Put on a stock one and things got a lot better. Will be leaving the jetting until I sort out the underbelly exhaust system.

I'm wondering if a later (ie 1996) model ZX7R motor will fit in my frame now. Would ultimately like to hollow out a spare fuel tank I have and fit up the pressurized airbox to it too.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top