Skydork's ZX7/9R


Skydork aka Jeff has put a '96 ZX9R engine into his 2000 ZX7R

Here's his guide to the conversion

Well, here it is guys! For those of you who care about this topic, I think this is the definitive answer to this question. I have just recently completed putting a '96 ZX-9R engine into my '00 ZX-7R frame. Despite the advice from people wiser than myself (Ken in particular), I had to give it a shot and see if it was possible.

First, I located the ZX-9 parts in a salvage yard and picked them up for $1,300 USD, which included the engine, alternator, starter, 41mm carbs, airbox, wiring harness, fuel pump, pickup coils, and CDI box. I didn't know exactly what I needed to complete this effort, so I paid for it all. In addition to the ZX-9 stuff, I purchased a conversion kit from BRG Racing, Inc. who has just finished updating their kit to fit all year ZX-7's (www.brgracing.com, or contact K.C. at 925-672-5789). The kit cost me an additional $325, which included the front motor mount relocation brackets, the oil plate adaptor and oil line, and lower radiator brackets. I also purchased an airbox adaptor plate to reuse the ZX-7 airbox on the new carbs for another $125. The BRG kit worked great, although it is a tight fit. I looked at what it would take to do this mod without the kit (just enlarging the cylinder head holes), and I don't believe it is possible on the left side as the motor mounts are offset from each other too much and you'd be drilling into the cylinder head itself on the left side.

As for the specific differences between the two bikes…..here they are:

  1. The cooling system is different. The resevoir tank from the ZX-7 is different, so you need one specifically for the -9R. In addition, you have to plug the upper cooling hose supplying coolant to the oil cooler. The ZX-9 engine splits this source off of the cylinder head just like the '93 - '95 ZX-7's so you don't need to get the coolant from the thermostat anymore.
  2. The electrical system is identical, however, I remounted the ZX-9R CDI box the the same bracket where I removed the old CDI and although the wiring is a little tight there, the connectors plugged right in.
  3. I was worried about the exhaust system since I had a nice Muzzy pipe, but when I got the engine and looked at it, my Muzzy SS carbon pipe for the ZX-7R fit right on it with no clearance problems. This of course, was after I bought the Muzzy SS head pipe for the ZX-9R engine. It won't fit! The downpipes on the ZX-9 engine are all parallel in front and the ZX-7 radiator is curved. The Muzzy ZX-7 pipe accounts for this by shortening the 2 and 3 cylinder down pipes to
    4. allow the radiator to fit. Anyone need a new ZX-9R SS headpipe???
  4. The ZX-7R lower radiator bracket won't fit the ZX-9 engine. BRG supplied a new setup for this and it works good, but you do lose the lower fairing mounts. No big deal, lighter is better, right?
  5. The other big thing is the airbox. I removed the emissions crap, plugged the reed valves on the top of the cylinder head, and reused the ZX-7R airbox and filter. It is definitely tight, but the gas tank does NOT have to use spacers for it to fit.
  6. As far as cables go, the hydraulic clutch slave cylinder bolts right on and I chose to use the ZX-9R throttle cables and route them through the hole on the right of the steering stem. The stock cables didn't look like they would fit nicely, so this is just how I chose to do it.
  7. I also chose to use the stock ZX-9R chain size of '530' on the bike. I was worried about the increase in HP affecting the -7R '525' chain, so I went for street-ability vs. overall weight loss. The sprocket alignment is perfect and there is plenty of tire to chain clearance using the wider '530' chain. Again, this is just how I chose to do this.

Now, as for how the bike works……MUCH better! Initially the bike drove pretty crappy, as the combination of the ZX-7 airbox and Muzzy pipe left the bike running real lean. I took it to a local shop and had them install a Dyno-jet jet kit, and that was the key. The bike is now putting out just shy of 132 HP at the real wheel, and it pulls real hard in all gears. I know there are a few more ponies dying to get out, but I need to find someone competent to do some cylinder head rework for me, and I don't where to go for that - yet. The handling is, for the most part, unchanged. The stability is still there, but the heavier ZX-9 motor, combined with the fact that the cylinder head is farther forward, shifted the CG of the bike more onto the front wheel, so it turns a little quicker and is a little more flickable. I had already dropped the forks in the triple-tree by almost a centimeter, and now I think I'm going to put them back to the stock setting to help compensate for the CG shift. Overall, I think the bike is perfect now, but that's just my opinion. Yeah, I could've spent my money better and gotten a new GSXR1000, but that's not what I wanted. Doing this mod was more about a personal goal to see if it could be done, as well as if I could do it. I think I did a pretty good job, and I am very pleased with the results. Now all I need is a set of Marchesini wheels, a new Ohlins rear shock and front fork tubes, a competion valve job, a new..........

And now...The ultimate step by step guide to the ZX7/9R conversion!!!

Kawasaki ZX-79R Super Ninja Conversion
Specifications: Conversion Steps and Information:

Picture 1)
This picture shows just the bare ZX-7R frame, subframe, and fork assembly.
Picture 2)
These are the new aluminum motor mount relocators that are supplied with the BRG Racing conversion kit.
Picture 3)
The new BRG motor mount relocators are installed into the existing threaded ZX-7R engine alignment pins by cutting off the "mushroom" head of the pins to allow for frame/engine clearance using the new forward mounts. The 2 rear engine mounts are identical between the ZX-7R and the ZX-9R.
Picture 4)
With the BRG conversion kit, the oil passage way on the left side of the ZX-9R cylinder head also gets relocated to clear the left frame rail. This is done by fitting a custom made oil plate on the motor which moves the fitting.
Picture 5)
This shows the oil plate adapter location and clearance once the ZX-9R engine is installed into the ZX-7R frame.
Picture 6)
This picture shows the ZX-9R motor installed into the frame using the BRG kit. The coolant tank mounted to the engine is for the ZX-9R. Although the ZX-7R reservoir tank looks similar, it will not mount to the new engine and must be replaced with the ZX-9R tank.
Picture 7)
The ZX-9R cooling system is slightly different from the ZX-7R's system in that the coolant is routed to the oil cooler from the cylinder head inlet. The ZX-7R, however, provides the oil cooler with coolant from the thermostat housing.
Picture 8)
By plugging the existing ZX-7R coolant line to the oil cooler, and just running the return line from the ZX-9R oil cooler back to the ZX-7R radiator, the system will function normally.
Picture 9)
The water pump and radiator connections on the left side of the engine are unchanged.
Picture 10)
The ZX-7R and ZX-9R electrical systems are identical. All connections on the wiring harness are the same for all electrical components. The Computerized Digital Ignition (CDI) box is slightly different, however, in the inside.
The ZX-7R has a redline of 12,500rpm while the ZX-9R is limited to 12,000rpm. The ZX-9R CDI box was used in place of the ZX-7R unit for rev-limiter and ignition mapping control of the new engine. The ZX-9R CDI box was mounted to the existing ZX-7R mounting bracket.
Picture 11)
The ZX-9R engine uses frame down-tubes to both support the engine and mount the radiator to, unlike the ZX-7R. So to reuse the ZX-7R radiator, a lower radiator bracket must be fabricated. BRG supplied two aluminum pieces to connect and support the lower part of the ZX-7R radiator to the ZX-9R engine. The exhaust pipe is also visible and the minimal clearance between the radiator and the headpipe. The exhaust is a Muzzy stainless steel system for the ZX-7R, not a ZX-9R. Because of the curved ZX-7R radiator, the ZX-9 pipe just won't fit this setup (at least not a Muzzy pipe). Something else that was modified, but not visible in this picture, is the Muzzy 5-bladed aluminum cooling fan. This was done to prevent the stock nylon 4-bladed fan from melting due to its proximity to the headpipe.
Picture 12)
This picture shows the left side cooling system connections and radiator mount. (Note the radiator mount on this side with the curved metal sleeve for the cooling hose to ride in. This prevents the new radiator mounts from cutting through this rubber hose from the vibrations). You can also clearly see the new braided steel oil line that is installed with the BRG kit to transfer oil to the camshafts.
Picture 13)
These are the stock ZX-9R carburetors installed on the engine. Two things of interest when looking at this picture are the throttle cam and the reed block off plates. The throttle cables hook up to the cam on the right side of the carb bank on the ZX-9R, not a center cam like the ZX-7R. Because of this, the ZX-7R throttle cables are just too short to reach this new cam location. Re-routing them through the right hand opening of the frame will solve this problem.
The reed block of plates on top of the cylinder head were purchased from Muzzy and allow the stock ZX-7R emission gear to be removed (less weight, more power, and more room for the airbox!). A ZX-9R baffle plate was also used.
Picture 14)
Another picture of the ZX-9R carbs with the right hand throttle cam. This also gives a good view of the float bowl vent line connections that were used with this setup. Due to the re-use of the ZX-7R ram-air system and airbox, the carburetor float bowls must vented to the airbox for pressure equalization or fuel won't flow!
Picture 15)
The stock ZX-7R gauge cluster was retained and since all electrical connections are the same, everything works the same in the cockpit as the stock ZX-7R engine. The tachometer pickup and instrumentation are completely compatible, and no difference is noticed between two system other than the physical placement of the paint for redline.
Picture 16)
This shows the stock ZX-7R airbox fitted to the ZX-9R carbs. Because of the different spacing of the carbs between bikes, a custom adaptor plate is needed to attach the airbox to the carburetors. The fit is tight, and there is no longer any room between the gas tank and the airbox, but it does fit.
Picture 17)
Again, here is the carburetor float bowl vent line connection to the airbox. The other holes in the airbox from where the emissions equipment was removed are plugged. The air filter inside is the stock ZX-7R filter, but with the metal retaining screen removed to smooth out the air flowing through the system.
Picture 18)
The last step was to put a new chain and sprocket set on the bike. The ZX-7R 525-chain was replaced with a 530 size. The 530 is standard on the ZX-9R and was used to handle the increased power of the new engine. The sprockets were also resized to give the new bike better acceleration performance. The green on the chain is not mold! They are supposed to be that way and match the color scheme on the bike.
Picture 19)
The bike is done and ready to be Dynoed!!!
Picture 20)
This is the dyno chart of the stock ZX-9R engine in the ZX-7R frame. A Stage 1 jetkit from DynoJet was installed to provide more fuel to the motor, which was desperately needed!!! The bike is a joy to ride, and the extra 20Hp over the stock ZX-7R is very nice!!! This is what Kawasaki should have produced.


If you need more information you can contact Jeff via e-mail at:  Skydork2K@aol.com