Jon Cornell's Custom Yamaha V-Max

One man's quest for reliable power—lots of reliable power

Jon Cornell's V-Max
Jon Cornell's V-Max has a suitably racy theme to match the power he added.Dean Groover

This article was originally published in the August 1999 issue of Motorcycle Cruiser.

Jon Cornell collects dyno sheets the way some people collect stamps. Each printout from a dynamometer session tells a story—some of great advances, some of failures, and others of compromises made to achieve a goal. But Cornell’s love of horsepower isn’t just an esoteric pursuit, this love of horsepower can be explained by the fact that he’s held a pro dragracing license since 1979 (he even held a few world records from 1981 to 1983). He still owns a blown alcohol funny bike, and a giant-killer Kawasaki ZX-11 is currently in the works.

Jon Cornell's V-Max
Jon is a horsepower collector and a gen-u-wine thermomechanical engineer and applies his knowledge to his V-Max.Dean Groover

However, Cornell isn’t just a horsepower collector, he is a gen-u-wine thermomechanical engineer. So his research is really in the interest of science.

Cornell bought his ’85 V-Max in 1994 with 15,000 miles on the odometer and a front end that had been heavily modified by an immovable object. He didn’t mind that the front wheel had become intimately acquainted with the engine’s bottom end. He’d wanted a V-Max ever since one pulled up beside him at a stoplight, the year they were introduced. Besides, the price for this Max was right and he needed a test mule; Cornell was planning to develop a fuel system for the V-Max. You see, he is the owner of U.F.O. Performance Cycles—as in Ultra Fast Objects—in Ohio, and he periodically builds a hot bike to act as a rolling advertisement of his company and his tuning ability.

Jon Cornell's V-Max
If the tire doesn’t explain, the license plate does.Dean Groover

For starters, Cornell replaced the damaged fork with a stock unit. Although the fork looks pretty now, it didn’t get polished until later. This V-Max spent the better part of a year and a half in R&D for the fuel system. “This bike probably has more miles on the dyno than on the odometer,” says Cornell. But that’s the nature of an intensive development process that has a lofty goal: deriving the maximum power from the brawny V-4 without diddling with any engine internals. Cornell wanted reliable, honest horsepower.

He found it.

His stock V-Max made 108 rear-wheel ponies on the shop’s Dynojet 150 dynamometer. Adding a Kerker header, 175 main jets and individual K&N filters bumped the peak power up to 121.4 horsepower and 78.6 foot-pounds of torque. U.F.O.’s V-Gas fuel system raised the peak figures to 128.5 horsepower and 89.6 foot-pounds. While the increase in peak power is impressive, the midrange is where V-Gas really shines. The Kerker/K&N power figures were 101.4 horsepower and 76.0 foot-pounds at 7000 rpm (after the factory V-Boost comes on-line). The V-Gas system de­livers a 119.5-horsepower wallop at 7000 rpm; an 18.1-horsepower increase—put that in your tire and smoke it!

Jon Cornell's V-Max
We also like the sentiment expressed on the sticker on the back of the seat.Dean Groover

Cornell’s V-Gas system consists of four aluminum intake manifolds, four rubber boots, four Keihin FCR 39mm flat-slide carburetors (42mm for 1500cc V-Maxes), four six-inch aluminum velocity stacks, and all the throttle cables necessary to install the system. According to Cornell, the entire system bolts on in less than three hours. First, all stock intake plumbing must be removed. Next, the V-Gas kit bolts into place, leaving the space under the faux gas tank gloriously empty as the new carburetors hang aggressively out in the breeze.

Jon Cornell's V-Max
Here’s the V-Gas system in all its polished six-inch-velocity-stacked glory. Loose items, pets and small children should be kept well clear of the intakes.Dean Groover

While the carbs play an important role in the V-Gas system, the secret to the well-rounded power delivery lies in the intake manifolds. The polished-aluminum manifolds are predrilled to bolt into position. Most importantly, the manifolds are ported in such a way that their internal shape flows seamlessly from the round of the Keihin carbs to the slightly oval shape of the head’s intake ports. The manifolds are even drilled and tapped to accept vacuum-gauge attachments for carburetor synchro­nization. For those who are afraid to run their engines without the benefit of air cleaners, individual K&N filters can be easily added. Or the fabric prefilter material used by dirt riders can be slipped over the stacks for some filtration with little power loss.

Since this V-Max was meant to be a rolling billboard for U.F.O.’s dragbike-­based business, a suitably racy theme was selected. The front end was fully polished, as was a good portion of the rear, by Joe Quintana. Chrome work was provided by Jon Wright. A SuperBrace and an ultrasexy 18.0 x 1.85-inch Kos­man aluminum wheel shod with a 25.5 x 4.50-inch Good­year Pro­stock slick were slipped in between the fork legs. To further lighten the rotating mass of the front end, the stock rotors were drilled before polishing. The calipers met the polisher’s wheel and received a new set of EBC Kevlar pads.

Mounted on top of the fork, a K&N drag bar sports a set of Arlen Ness grips. Galfer braided stainless steel hydraulic lines also grace the bar. When asked about the lack of mirrors, Cornell responds, “I never look back. What’s gone is gone.” A stock seat, specially cupped by U.F.O., holds him in position while he puts things behind him.

Jon Cornell's V-Max
The polished and clearcoated swingarm was modified to accept a seven-inch slick. The OE shaft manages to handle the impressive 128.5 rear-wheel horsepower.Dean Groover

Out back, behind the Kerker ex­haust system, the stock swingarm was polished and modified to accept a seven-inch slick. Making the necessary link between the 25.0 x 7.00-inch Goodyear slick and the swing­arm, a Kosman 18.0 x 6.00-inch aluminum wheel grafted to the stock hub delivers all 128.5 horsepower from the stock shaft to the pavement. Finally, two of our favorite touches reside on the very rear of the Max. The license plate reads “NADS” because that’s what it takes to ride this monster. Also, tucked underneath the grab rail, a little sticker proclaims, “Praise the lowered.”

Cornell says whenever anyone asks him about riding his V-Max, the first thing they inquire about is if the square profile of the slick makes the bike hard to ride on the street. Although he only runs about 20 pounds of pressure in the rear to keep it flexible, he points out the skinny front tire and the square edge of the rear slick, saying that cornering traction is limited. But this bike isn’t about railing through turns; it’s all straight-line power. And powerful it is. The bike carries the front wheel all the way through first gear, and occasionally the meaty rear tire barks on the shift to second. Only when third gear comes around does the front slick touch the pavement.

Jon Cornell's V-Max
The stock fork was polished and adapted to hold a Kosman wheel. The rotors were drilled to remove excess weight.Dean Groover

When asked why he chose the V-Max to showcase his tuning ability instead of one of the current crop of sportbikes that are popular in drag­racing circles, Cornell re­sponds, “If you ask me, there are three types of motorcycles: sportbikes, cruisers and the V-Max. If an American company were to build a musclebike, it would be a V-Max. Think about it, a V-Max is half a V-8—the all-American en­gine. Look at what goes in most hot-rod cars. The V-Max is the perfect American musclebike.” People who want their V-Maxes to perform like Cornell’s should call U.F.O. Per­formance Cycles.