We all remember our first taste of blinding two-wheeled acceleration. Maybe it was hitting your first powerband on a two-stroke dirtbike or that first rip to redline on a sportbike. But no matter the vehicle that delivered the hit, what we recall is the euphoric sensory overload that followed; something so intense it left you speechless, trembling and ready for more.
Like most go-fast junkies, it had been a long time since I'd last had to check myself on a bike. That was, until I threw a leg over this turbocharged Kawasaki ZRX1200. After one trip up through the gears I was hooked. Full boost arrives at 5000 RPM and from there, the needle rockets around the tach so quickly your left foot can barely keep up. And unlike a naturally aspirated engine, the power-curve is nonlinear-it goes from robust to rocket in roughly 1000 RPM. From there you better hang on because it keeps pulling exponentially harder until you're ready for the next shift. Forget an S1000RR or even a 'Busa, if you want arm straightening power, a turbo bike is your ticket to ride.
"From the moment I bought the bike I knew I wanted to turbo it, that's part of the reason I went with a ZRX since its ZX-11 derived motor has had years of aftermarket development," owner Mike D'Agata said. "The horsepower is nice, but on the street it's the 170+ LB-FT of torque that makes it fun. It's the kind of hit that sends the front wheel flying or the rear wheel spinning."
This isn't a slapped-together turbo kit. Mike did, however, try the inexpensive route first.
A Turbosmart blow-off valve...
A Turbosmart blow-off valve was used to expel the boost when the throttle is suddenly closed.
The menagerie of gauges helps...
The menagerie of gauges helps the rider keep an eye on the turbocharged terror: oil temp, boost, air-fuel ratio and coolant temp.
Öhlins rear shocks, Trac Dynamics...
Öhlins rear shocks, Trac Dynamics swingarm, Brembo brakes, Carrozzeria wheels; you get the point-this thing is hooked-up!
"I bought a used turbo kit from a member on the forums who was having problems blowing his motor. I didn't pop my motor, but I had problem after problem and it left me stranded on the freeway many times."
The hand-me-down turbo kit made 185 HP and 132 LB-FT at the tire on the stock internals. However, its gross unreliability sent Mike in the pursuit of perfection.
"Thankfully I come from a family of machinists because I spent the next year or so recreating the turbo kit. I used the first kit for reference and perfected it along the way."
Being a machinist sure paid off because the new boost setup is top rate. Mike fabbed a new log-style turbo manifold, boost plenum, the charge pipe and everything else needed to make it reliable. Along the way he also tweaked and polished all sorts of bits to make it boost friendly. The turbo was even upgraded to a hybrid T28/16G TD04 unit and then jet coated for serious boost.
Of course, a custom turbo would be nothing without a stout motor, so Mike and his brother filled the engine with forged goodies like Carrillo rods and custom 1224cc JE pistons, then sandwiched them in between larger Muzzy cylinders. The upgrades were designed to handle 20+ psi of boost.
Before letting the cat out of the bag as to what type of power this ZRX is making, let us highlight a few more of the custom goodies. Take for example the fittings and stainless steel hoses running from the turbo to the oil pan. Knowing that his turbo needed an oil-feed line to keep it alive, Mike did some research and discovered that the ZX-11 engine had an external oil cooler. While this cooler wasn't used on the ZRX, he realized that the same architecture existed on his engine. So he tapped the pan and instantly solved his problem.