Fast Kawasaki

FAST KAWASAKI

Roger McPhail's Record-Holding Stock-Class KZ1000 Turns 11.54

John Ulrich

If you think the KZ1000 is out of the hunt in the high-performance sweepstakes, take a look at Roger McPhail's 1978 Kawasaki. McPhail, 28, is Sales Manager and Technical Consultant at Vance & Hines Racing (VHR) in Southern California. When he's not answering phone calls at VHR to give advice and information to customers, he's likely to be working on his bike, which holds the Dragbike national E.T. record of 11.54 sec. in the B/Stock class. And while McPhail's machine doesn't hold the official terminal speed record for the class, it has broken the 115.53 mph record twice in unofficial practice runs during a local dragstrip's Wednesday night grudge races, turning 117.03 mph.

B/Stock rules allow racers to make external gear ratio (i.e., sprocket) changes; install flat or clubman handlebars; remove turn signals, passenger pegs and centerstands; re-jet the stock carburetors, run aftermarket shock absorbers and remove the air cleaner and airbox. Engine blueprinting is not allowed. D.O.T.-approved street tires are required. Struts and wheelie bars cannot be used.

The class has a minimum weight for each machine, based on the manufacturer’s dry shipping weight and the “average rider” figure of 150 lb. Bike and rider are weighed at each race.

Generally, the weight lost by removing such things as turn signals and stands is gained by the addition of gas and oil or the weight of the rider.

McPhail tries to run his bike as close to the minimum allowed weight of 679 lb. as possible, a task made simpler by the fact that he weighs exactly 150 lb., the weight specified in weight break calculations. “Weight reduction is free performance in drag racing,” says McPhail.

With that in mind, he removed what the rules allowed, and installed flat bars. He fitted shorter-than-standard Zl-R throttle cables to prevent an unsightly loop of cables around the instruments, then went to work on the suspension.

McPhail lowered the front suspension by disassembling the front forks and installing 1.5 in. spacers on the damping rods, spacers which prevent the fork from fully extending. Then he replaced the stock KZ1000 shocks with shocks off a KZ650, which are about 1.5 in. shorter.

With both ends of the bike lowered, the machine’s center of gravity is closer to the ground, which makes it less likely to wheelie off the line. With less tendency to wheelie, the rider can leave the line harder, almost popping the clutch. Hard launches lead to good E.T.

There’s more to it than that. McPhail switched from stock lOw fork oil to 20w, and adjusts the shock spring preload to suit track conditions.

McPhail starts with preload in the middle position. But if the bike starts to wheelie off the line, he increases preload. Conversely, if the rear tire tends to spin, he reduces preload.

Gearing is 15:35. Clutch springs are heavy duty ones available from VHR, but McPhail retains the stock Kawasaki clutch plates because they have a very smooth and progressive engagement action.

McPhail experimented with both the airbox in place and the airbox removed. He found that using velocity stacks made carburetor adjustments critical, but also made the bike run quicker. With the airbox in place (without the element or air intake horn) carburetion adjustment is less sensitive, but the bike doesn’t run as fast.

Ignition timing is stock. The camshafts haven’t been degreed in. Valve springs are stock.

“If you’re going real fast, everybody watches every move you make and if they take your engine apart (under protest) they check real close,” said McPhail after one race. “I like to keep a positive cushion so there’s no question of my legality. I try to take the rules at face value instead of trying to push them to their outer limits.”

Why then, does McPhail’s Kawasaki fly? He attributes it to the bike being set up right. “We use the proper jets,” he says. “Reading the spark plugs is very important with that bike. Larry Acedo, my partner, and I both keep reading plugs, checking the bike and making adjustments to get it to make the most power. We go for the most mph. If the bike isn’t making a good mph (figure) then you’ve got problems.”

Besides varying jetting, McPhail selects NGK B8ES, B9ES or B10E spark plugs, depending upon conditions and jetting.

“Come on,” a reporter told McPhail when given the above information. “This thing has got to trick. There has to be a secret. What’s the last 5 percent of your tuning secrets that you’re withholding?”

“Well,” said McPhail, “the only rear tire that hooks up is an IRC. When I first got the bike I found that out by experimenting. I even talked to the IRC guys about some tires, but I ended up just going out and buying one. I run pressure varying from 10-15 psi. You can figure out what pressure is right by looking at the tire print from the short chops (burnouts) before you get to the line. You don’t want the tire to curl under, and you don’t want it to spin. Larry (Acedo) watches the tire for me, and makes pressure adjustments.”

That’s it?

“Yeah,” says McPhail. “Except for one last important thing. My brother, Robert McPhail owns half the bike. Don’t forget to mention him.”

There’s no doubting that McPhail’s Kawasaki is fast. It holds a national drag racing record. McPhail’s fine tuning and excellent set up is why. B!