Sigvart's ZX7/950R


Sigvart has put a bigbored '95 ZX9R engine into his 1996 ZX7R.
145.5bhp at the rear wheel was not enough for our man so he decided to tune it further

Here's the list of his mods (Phase 1 and 2) and the bike's spec

Ok then, just a few words about my little mod.

To start with my ZX7 was a 1997 with a Quill slip-on and a dynojet kit, then I got a Yoshimura RS3 Oval Competition system and bored it out 1mm with J&E HiComp pistons.

Phase 1
Then I bought a bigbored -95 ZX9 engine, 2mm overbore/HiComp Cosworth pistons, and installed it with 39mm FCR`s with blue velocity stacks, inside an AirTech Superbike style airbox (encloses the carbs inside the box) modified to fit the stock ZX7 air filter, fcr`s jetted after the Kawa kit manual and few Dyno runs. ZX9 CDI.
Puts out 146 bhp, but was running to rich due to too big mains.

Phase 2
I have just installed a Kawa kit camshaft with adjustable cam sprockets and single race valve springs, cams degreed to best top end.... Adjusting the squish (piston to head) clearance to a minimum by removing the cylinder decks lower gasket. Porting the inlets with epoxy to make them smaller, and roughing up the inlet surface at the same time.
I`ll also do minor modifications to the ignition chambers, and measure the compression ratio.

Other mods I`ve done:
Change brake pads to Ferodo 916* Racing pads, removed dust shields on the calipers, changed to steel braided brake hoses. Installed straight rate 9.5 kg/mm Ohlins springs and RaceTech GoldValve kit in the forks.
Ohlins shock with hydraulic preload and remote reservoir.
Raised the bike, front and rear, to jack up the CG.

I use a 15 tooth sprocket front and 44t rear (I think the ZX9 engine sprocket is a little bit further front biased than the ZX7), and I can just stretch the chain to fit. Using a 43t rear is no problem at all. I was only warned that decreasing the wheelbase could make the bike more wheelie prone, but that is not a problem. The ZX7 is so front heavy that it is not a problem.

Soon coming from the US; new rear sets, smaller/lighter rear brake caliper bracket who locates the caliper over the swingarm, not under. Crash pucks in aluminum. Kawa kit shock rocker and shorter "dog bones" for the rear suspension linkage, makes it more linear.
Going to buy a 98+ zx9 sidestand to accomodate the higher bike.
Maybe I`ll buy a 94-97 ZX9 swingarm (longer than the ZX7) to help with traction and prevent the wheelying.

Kawasaki ZX7/950R Conversion - Phase 1
Specifications at a glance: Phase 2
Specifications as above plus: Pictures and Information on the tuning done:

Phase 1
DynoChart)
Here's a picture of two of my dyno runs. And from what you can see of the graphs, the low down torque and hp is very good. You have to understand that the graph with best high end and worst low end is not really like that....It was one of the last runs so we didn`t bother to feed the trhrottle under 5000 rpm, thats why the graph is a little bit low compared to the other. So at the end, it was the best of two worlds, the best low end and the best high end of what you see on these two runs. 39mm fcr`s is 1mm down from the original cv carbs, so only that fact would help the low end response, if nothing else was tuned. But I also installed Kawa kit-manual carb setting (fuel and airjets, needles and float heights). The dyno runs showed I didn`t miss by much, but it showed a rich spot at the top. A leaner set of mainjets would have given me slightly more top end. We didn`t bother to change the main jets at that point, thought of the cold weather in the fall, but I bought a set of leaner jets to try in the summer. An example, in second gear, at 2500 rpm, I can jerk the trottle (not wide, but close to) open, and get instant pull. At 3000 rpm I can whack it full open, and it just takes off. Let me use wheelies to tell you; accelerate to 5000 in 1st, and whack the trottle open, UP fast!! 2nd gear, 6000 rpm, trottle on-off, UP slow. But the best feeling is throttling hard in 3rd over small hills on the road, and let the negative G lift the front. Let me tell you, I`m not a wheelie fan, but the way the fcr`s controls the engine makes me look good, haha.

Phase 2

Raising the compression
First I checked the cam timing of the stock cams, using a degree wheel on the crank pick-up mount and a travel indicator on the valve retainers I could find the cam duration's and lobe centres. And they where faaaaar from optimum......




Here's a better view from above and a homemade tool to find Top Dead Centre (Made using a long bolt and part of an old spark plug).


Then I removed the head and installed soldering wires (1.6mm thick) on top of the pistons to check the "piston to head" clearance. Kit manual says this clearance should be somewhere between 0.65-0.85mm on a ZX7, and mine was 1.02mm.

To reduce this clearance I removed the gasket between the cylinder rack and the lower part of the engine, this brought me down to 0.76mm, which is a little bit on the tight side for a ZX9, but I decided to try it out.

The pieces of soldering wire should be installed in the pistons in four "clock directions", 12-3-6-9....or in the pistons four "map directions", North-East-South-West.
Bolt on the head with the old head gasket, turn the engine one turn, and unbolt the head again (it`s easy, just the head, the cams do not have to be installed).

You`ll know that you have compressed the soldering wire, because you will feel the crank getting heavier to turn. Or you could just shine a flashlight down the sparkplug hole.
Now you can use a micrometer to measure the piston to head clearance by measuring the thickness of the pieces of soldering wires. If you find the clearance to be 1.00mm, then you can remove the cylinder decks base gasket which is 0.24mm, and you`ll have 0.76 clearance.

Cylinder Head Porting
First I gave the cylinder head a thorough wash before I started rubbing down the inlet ports, and drilled small notches for the epoxy to hold on to.
Nice and clean. Notice the notches in the inlet ports. Roughening up the ports with sandpaper will help the epoxy to take. Also (when the engine is running) slightly rougher ports create more turbulence for the fuel/air mixture hence giving a better burn.
A close up view of the notches drilled into the ports to give the epoxy something to hold on to.
After applying the the epoxy and waiting for about 24 hours I could start measuring the required inside diameters with an "inside caliper", and grind down the epoxy with my Dremel.
Had to be Really careful around the valve pockets, but I got away with it...

The finished items.

Racekit Camshaft & adjustable sprockets
After installing the valves and rocker arms I installed my new Kawa Race Kit intake cam with adjustable cam sprockets and the exhaust cam, which on I had pressed off the old sprocket and pressed on a new adjustable one.

Timed both inlet and exhaust cams to more optimised numbers (top end hp`s), and then re checked that I had done it right...three times...
Also checked that the increased lift didn`t cause the valve springs to go "coil-bound", but no worries there, they checked out ok. (I was supposed to use single race springs, but didn`t have the correct retainers...)

I finally got a chance to take the bike out for a ride yesterday, and it is MENTAL !!!! The increased compression and optimised squish (piston to valve clearance) makes it really "angry", the kit cams really takes off from 5.500-6.000 rpm and all the way to the top, and the epoxy porting works great all over the power curve. I think its the epoxy that now gives me the opportunity to open the throttle in fourth, up hill, at 3.500 rpm, and it still pulls cleanly and strong !!! I haven't bothered to write down in detail what I have done, but if any one ask, I`ll be more than happy to write more about the subject. Oh, and a BIG Thank you to my "On-line" mechanic John Steinar Vivelid, whom I called night and day, and who supplied me with parts and good advice. I would call him Norway's number one Kawa tuner, stroking ZX7`s to 1000cc`s, ZX9`s to who knows what cc`s and building Raptor engines...!!! That's all for now, (will of course run the bike on a Dyno as soon as possible),

Kawasaki Racekit camshaft (intake) with single race valve springs


Ride height to Preload Adjusters
These are my fork spring "ride-height to preload" adapters. They work backwards (wind the adjusters in to reduce preload and vice versa to increase it). The adaptors occupy 15 (or was it 17?)ccl of air, the air gap should be increased to compensate.

Homemade tool to adjust the fork oil level

Updated Dyno chart to follow soon