HomeFeatures & ColumnsKawasaki's ZX12R Turbo: The Big Sexy

Kawasaki’s ZX12R Turbo: The Big Sexy

Fans of Kawasaki sportbikes have largely had to sit on the sidelines lately when it came to super high-performance, ultimate streetbikes. While Suzuki tuners were cranking out 220, 240 and even 260hp all motor versions of the ubiquitous Hayabusa, ZX-12R fans had to be content with around 200hp for big bore bikes, while a little more was available with the popular Muzzys stroker crank. Not to mention the steady stream of turbo Busas’ that seem to be everywhere, including the pages of Dragbike.com

Supporters of the great handling ZX-12R don’t have to wait any longer to have serious power just like their Suzuki riding buddies. Early in 2003 Velocity Racing announced they would soon be releasing a street version of their turbo system. This was intended to be a bolt-on system that would produce a nice street bike that is both ride-able as well as delivering a solid 275hp.

Nice we thought, but (yawn) we had already reviewed the 299hp Hayabusa by Velocity in 2002 so this time we wanted something different, something a bit more radical. We called Barry Henson (Owner of Velocity Racing and AMA ProStar rider and asked if he was interested in building the fastest ZX-12R streetbike in existence. His answer was, as we figured a resounding yes.

This project started with a trip to White’s Cycle and Marine and Chattanooga, TN where we purchased the donor bike for this story, a nice new 2003 ZX-12R Kawasaki. We have dealt with White’s for years now with this being the fifth bike purchased there in as many years. Their sales staff actually rides motorcycles and the parts manager Tim Holder (FTP-Timbo) is a fellow land speed racer at Maxton. So they know motorcycles.

It seems a shame to take a brand new bike and promptly drop the motor and start the turbo process so the bike was actually ridden a few times to get some break-in miles on the tranny. Since the whole top-end would be replaced anyway there was not much use in following the Kawasaki break-in so right off the bat this one was hammered. Don’t tell me you haven’t always wanted to get a brand new bike and redline it right off the showroom floor.

Just so we would not forget what she looked like stock we made this photo on its maiden ride.

After dropping the bike off with Velocity at one of the ProStar events we told Barry to pull out all the stops this time and shoot for the outer reaches of the performance of the 12 and still maintain some semblance of a street bike. From the outset the goal was to reach over 215mph top speed and make this the fastest Kawasaki ZX-12R.

As expected, to get this kind of power a trip inside the engine would be needed. No more simple bolt-on spacer plates and stock con-rods for this bike. So the motor was yanked and promptly send to Kevin at Total Kaos Performance. Kevin is a distributor for Velocity Racing turbo systems and does all of the motor prep work as well for Barry. In this case we needed just about everything beefed-up. Crank work, new con-rods, lower compression pistons, adjustable cam sprockets, better valve springs and a locker clutch.

Kevin has 24 years of engine building experience including 19 years working on turbo diesel engines. He estimates that he has built about 35 turbo bikes using the ultra reliable Velocity turbo system in the last year alone. After spending some time with him we get the feeling that he is the type that would argue over .0001” clearance. While there is not one major secret to building a good reliable turbo motor, Kevin feels like it is a summation of numerous little details that make the difference in a good one and one done in your buddy’s basement. This is where Kevin spends his time. While he was not willing to share all his secrets with us, I think it is safe to say that he knows what he is talking about, so we left the engine work to him and did not try to play professional engine builder.

As soon as the engine was pulled apart the first thing we did was to send the crankshaft to APE. Since the Kawasaki we used is the 2003 model it is the new motor configuration with the heavier crank which Barry felt was ideal for this project. So instead of severe lightening, we simply had a good balancing done on it.

Before balancing the crank APE flutes the rod journals to keep more oil on the bearing surface as shown below. This work must be done prior to balancing to ensure that the metal removed in the stage does not affect the final balancing.

APE uses dynamic balancing as opposed to static balancing. The difference is quite a bit more involved than we imagined. For example if you had a crank that was 30 grams heavy at a certain radial location on one end, and 30 grams heavy 180 degrees around on the other end, that crank would be in perfect static balance. Since each of the 30 gram overages would cancel each other out. However, if you attempted to spin that crank at high rpms, it would then act like two out of balance wheels connected by a common shaft.

A dynamic balancer measures the out of balance through an X plane throughout the crankshaft. It would show this crank as being 30 grams heavy on each end and require a correction to be made. It takes a very sophisticated machine to measure this imbalance but to the pros at APE it is commonplace. They would then take this reading and make corrections down to a forth of a gram. That’s .25g which is pretty amazing.

After running our crank on the dynamic balancer it was found to be .86 grams heavy on the left side and 1.62 grams on the right side. The numbers beside the weights represent the radial location of the heavy section. Jay reports that this is actually very good for a factory crank and they get them as much as 4 grams out of balance at times.

After the balancing was done the irregularities are down to only .14g on the left end and .18g on the right end.

We also had Jay set us up with some new valve springs. After checking the factory seat pressure we were shocked to find that they only had about 38lbs. With the new springs from APE this was boosted to a respectable 63lbs. This will allow our engine to close the valves against the high boost we anticipated and prevent them from floating at high rpms.

The spring on the left is the Kawasaki oem part. Notice that this spring is progressively wound for almost half its height. A spring with this construction will not respond to shimming due to the design. The only option is to replace it with a high performance spring like the APE spring on the right. Not only does it raise seat pressure, but it also has .120” more travel before coil bind allowing the most extreme high lift cams to be used. APE also has TI retainers available for an additional $199.

Lastly from APE we picked up some billet adjustable cam sprockets. These are needed to get the cam timing dialed in to optimize the power of the turbo. Since cam timing is quite often different from stock, these sprockets allow the engine builder to make these changes very easily.

One of the keys to any good turbo engine is the proper compression ratio and pistons that can handle the boost. For our pistons we turned to JE Pistons. Our contact at JE is John Noonan and as a land speed record holder at Bonneville John knows lot about high performance engines. JE made us a set of custom turbo pistons specially designed for the ZX-12R. Of course they are forged pistons, and have the ideal compression ratio for making big boost. These along with the Cometic Gasket supplied spacer plate and high strength base gasket, results in a compression ratio of about 8.3-1. JE sells the pistons for $658.

After receipt of the pistons Kevin (our engine builder) insists on polishing the edges of them as a trick to prevent pre-ignition. Even a microscopic burr will result in a hot spot under the extreme boost pressures we intend on running. These hot spots will pre-ignite the fuel and ultimately result in detonation or engine failure.

To connect the new pistons to our balanced crank we selected Falicon con-rods. Barry uses them in his AMI dyno shootout winning bike (505hp) therefore he knows they will stand up to a ZX-12R street bike. Falicon now uses the ARP multi-phase bolts which offer the best connection available anywhere. These bolts cost $152 for the set of eight. For those of you interested Falicon also offers cryogenic treatment as well as an isotropic finish to reduce friction. The rods retail for $876 for a set of four.

In order to get all this power to the back tire we would need a locker-clutch. For that we turned to Muzzys. After-all, who knows more about making power and putting it to the ground on a twelve than Muzzys? We bought their entire locker clutch package which consists of a new billet basket, the lock-up clutch assembly and the clutch plate kit. It also includes a spacer plate needed to extend the side cover of the engine to fit all these trick parts inside. As compared to a normal clutch the locker offers 100% positive lock up and assures you that all of your power is getting transferred to ground instead of slipping the clutch plates. The entire kit retails for $1287 assuming you return your stock clutch basket as a core. Otherwise add an additional $195.

Now that we told you all the details required to harness the 20 + PSI of boost we plan to throw at the engine, lets talk about the turbo system itself. We were so happy with the performance of the Velocity Racing turbo that we used on the 2002 Hayabusa that we did not even have to think about where to turn for this Kawasaki project bike. While the turbo busa was a tried and true system, the Kawasaki presents it’s own set of challenges not present on the Suzuki. First is the airbox. Since the ZX-12 uses its frame as an airbox it would have to be airtight enough to hold the boost of the turbo. So the first order of business was to weld up all the little holes and ram air tubes etc etc. Even after that was completed there was still significant leakage around the area that the throttle bodies mount on the engine, so additional modification was required.
We also had to select a slightly smaller turbo than our original plans called for. Barry had hoped to fit a larger unit from Garrett but space limitations dictated otherwise. Even with the removal of the stock oil cooler there just is not enough room, thus we used a GT-25R, which is a dual ball bearing design and an optional upgrade that adds $650. But after you hear that turbo spinning as only a dual ball bearing unit does, you will know it was money well spent.

Once that was taken care of, the next challenge was space for mounting the turbo. Originally we had intended to fit an intercooler to this bike but due to space restrictions and lack of an aftermarket raked triple-tree Barry was forced to scuttle the idea and go with the tried and true water injection as we had used before.

Speaking of Barry, I had the chance to spend a few days at his Davie, Florida race shop as part of this article and I think it is important for you to understand what makes him tick. I arrived in S. Florida at about 10:30pm and was greeted at the airport by his brother (and Velocity staff) Frankie. Expecting to be taken to the hotel due to the time, I was instead taken straight to the shop. Once I arrived there on a Friday night I was shocked to see a flurry of activity going on. Several mechanics were working on various customer bikes and a fabricator was welding up pieces for the bikes in progress, all this in addition to Barry trying his best to sing along to the 80’s music that was playing in the background. Without being too critical I will just say that it is a good thing that Barry can ride and build some of the fastest motorcycles in the world because if Simon from American Idol heard what I did, he may not be as kind as I am going to be regarding his harmony.

There was a Street Stage II turbo ZX-12 that was just being finalized for a customer pickup in addition to some full on race kits being put on the Busas in the shop. There were also several R&D bikes around such as a Harley V-Rod, a Honda VTX1800, which I had a chance to ride later on. As well as the normal compliment of GSXR1000s and Hayabusas.

By 1:00 am I was crashing hard but Barry was still running wide open just like his world record setting Honda Turbo-Blackbird that he pilots in the AMA ProStar Super Streetbike shootout class. While talking about the state of tune I wanted the Kawasaki in when it left the shop I stated that while I wanted a really fast bike I would be happy with a reliable 300-325hp and that would be more important to me than making a few extra ponies that I am not likely to use on the street anyway just to say it has 375hp. He smiled and called me a “bitch”, meaning that he prefers to run as much power as he can and is not really into tuning a bike “down ”.

Other than the peculiarities of the Kawasaki, the turbo system is very similar to the kit we installed on the Busa last year. It uses piggyback injectors that are controlled by Velocity’s own black box that can be mapped with a laptop using their own software. The software is actually quite friendly and is very similar to other fuel injection mapping systems on the market. It allows for fuel curve throughout the rev range as well as at various boost levels. This insures that the fuel curve does not go lean and hole a piston at peak boost.

We also used a DynoJet Power Commander PC-IIIR to map the non-boosted portion of the fuel curve and to remove a few degrees of timing to ensure we don’t run into problems during long, high speed runs. It retails for $403 and is a wise investment for a street rider or racer to properly tune your bike.

The water injection system is activated with a pressure switch that turns it on at a predetermined boost level. Barry sets this up to activate at 8 psi. This very sophisticated water system adds just the right amount of spray to cool the intake charge at these elevated boost levels. When a turbo starts making a lot of boost the temperature naturally raises due to the pressurization of the charge. The use of cool water reduces this temperature and allows the engine to manage the heat without the need for an intercooler which is a good thing since we were unable to find room for one. Cars commonly use air-to-air intercoolers but they have more space to house one that is large enough not to be restrictive to the airflow. This is often not the case on motorcycles so compromises have to be made. Typical temperature drops using a water injection system are in the range of 100-110 degrees.

Velocity offers two basic kits for the ZX-12R with the first being the bolt on kit. This means the engine is dropped and compression is lowered with a base gasket then the turbo is bolted up with the modifications mentioned above. It uses the same two stage Tial wastegate shown in this system. On low boost 6 psi that system produces a nice rideable 210hp. Then at the touch of the horn button the boost is then jumped up through the vacuum system to about 12 psi. The bike I saw dynoed actually made over 300 hp but it also had turbo pistons fitted from JE. Barry says that is not typical and he usually promises about 285hp from that state of tune. The impressive thing to me about that kit was how easily it starts and idles. It can be had with a full exhaust or a dump pipe. Or both can be made for an extra charge.

The cost of that bolt on system is $5995. If you choose to upgrade to the turbo pistons it adds another $700 and the water injection adds another $700. Due to the complexity of the ZX-12R installation Barry is not selling the kit only and instead only sells it installed. Either from him or one of his dealers like Total Kaoss Performance. The install fee for this one is $2000. After watching a lot of this work being performed it is well worth it to get it installed and professionally mapped. That is a complicated bike to deal with.

As you would expect the power is very impressive. The turbo spools up well on the road without a lot of lag that often goes along with high horsepower bikes. What is it like to ride you ask? Well I am afraid my ability to convey the feelings I get while riding this beast will be the limiting factor as I try to give you a glimpse of what it is like. Even with gearing for the 220+mph the bike’s manners on the street are pretty normal, that is until you really twist it. Then the symphony of mechanical sounds below you start to stir emotions and sensations I have never felt before. While running with the dump pipe you can really hear the whine of the turbo which is as it should be. Who wants to ride a turbo and not hear that incredible high pitched whine right?

In the first gear it is best to stay away from the horn button or else risk SFS (sudden flip-over syndrome) SFS is a common problem that plagues many of Velocity’s turbo bikes. Especially those that keep the stock arm length.

Now buckle in as we take you on a narrated ride that this bike actually took place at the ECTA, March 2004 meet. With the 18-38 gearing (stock is 18-46) first gear is good for 95 mph and second ups the ante to 127mph at 11,000rpms. Once you hit third it is safe to make a stab at the horn button and uncork the turbo. This brings the boost up to about 20psi and before you have time to realize that the front end is still skimming the tarmac you are already at redline in third which comes at a 168mph. All the fooling around is over as you realize this bike plays for keeps. So now its time to tuck in hard and keep everything out of the jet-stream you are fighting against. Another tap on the shifter gets you into forth gear.

Now your brain reminds you that you are over 185mph as you knick another gear into territory that most people will never know. We are talking two hundred miles per hour. At this clip you are covering the length of a football field in .977 seconds, a full mile flashes by in a mere 18 seconds at this speed. The rider braves on and decides all bets are off and make one more stab at the gearbox as the speeds sneak past 205mph at the end of fifth gear. In sixth now the wind noise is deafening and everything is a blur except the tunnel that the pilot sees as he heads for the timed section of the one mile course. In another flash the bike is now pulling hard towards it’s redline. Running out of runway the throttle is finally released as the bike passes through the timing lights.

Knowing better than to lift out of the tuck he instead grabs a big hand full of the AP Racing brakes and the bike nosedives down from speed. As the bike crosses back into earth’s atmosphere he finally sits up and feel the tremendous wind blast that is still fighting against the Big Sexy Kawasaki’s frontal area at 180mph. It seems almost slow by comparison as the speeds drop below 150mph taking the short turn off. That ride resulted in a new ECTA land speed record in the S/BG-1350 class at 218.56331 ridden by The Master of the Maxton Monster Mile, Lee Shierts making it the fastest ZX-12R ever at this venue as of this writing. (This record was actually broken a month later at the April Maxton meet by .1 mph) On a windy day in North Carolina that is fast.

In addition to the full engine build up on this bike, we also opted for some other trick bits. Such as Carbon fiber wheels from Dymag, AP racing brakes, and lots of goodies from Schnitz Racing. We also tried some custom embroidered seat skins and a tank cover from Second Look. Stay tuned for part II of this build up when we bring you up to date with those accessories and a lot more.

For now enjoy the eye candy below with special thanks to the model. Rhonda Bright of Chattanooga, TN


Photos by Don Smith & Mike at Intelatours

Read more about this Project in Part 2

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