Yamaha V-Max

YAMAHA V-MAX

ENGINE MODIFICATIONS TO the V-Max consisted entirely of changes to the exhaust system and carburetion. The standard exhaust was replaced with a Kerker prototype pipe. a 4-into-2-into-1 design that snakes about to maintain equal-length headers. With competition baffle, this pipe was entirely too loud for the Street, but sounded wonderful. A street baffle brings the noise down to simply loud, but at some cost in power. Kerker has now put this pipe into production.

Carburetion changes were ex tensive. First, the V-Boost valves connecting the carburetors were removed and replaced with open tubes; each V-Max cylinder now a/wars breathes through two car buretors instead of doing so only at higher rpm. Then the carbu retors were rejetted to work with out the V-Boost, and with individ ual air filters.

The overall result was an in crease in power from 115 horse power at 9000 rpm on Kerker's rear-wheel dyno to 124 horse power at the same engine speed. More important, power falls off much less sharply in the modified engine: at 10,000 rpm. it's still making 1 2 1 horsepower, com pared to 98 for the stocker. The removal of the V-Boost didn't re duce low-speed power: instead, low speed power was increased, and a hole in the powerband around 6000 rpm was removed. Unexpectedly, the more linear powerband of the modified V Max makes it feel slower, without the V-Boost's kick in the pants, but it's measurably faster under all conditions.

Chassis modifications reduced weight and allowed the use of an 18-inch drag slick, exactly the same tire used on over-200-horsepower Pro-stock bikes. A standard V-Max weighs 599 pounds with out fuel; the modified Max weighs in just under 540 pounds. Of the lighter components, the most dif ficult for Kosman to fabricate was the spoked rear wheel; to make it, a stock V-Max wheel was turned down to just a hub, and a custom made spoke flange was shrunk on over it, securely located by bolts

that normally secure the rear disc. This job took a machinist more than eight hours, although Kosman thinks he could do it

more easily and cheaply on a sec ond try. Still, an 18-inch rear wheel for a V-Max will likely never be inexpensive.

Engine

Kerker 4-into-2-into1 exhaust $379.00 Kerker/Dynojet jetting kit (`c~.

• 250.00 Engine total . $629.00

Chassis

Front wheel . $250.00 Front brake

caliper . 210.00 rotor 275.00 master cylinder andline 115.00

Rear wheel hub 610.00 5.5x 18 in. rim 287.50 spokes 40.00

Rear brake caliper 210.00 hanger 35.00 rotor 90.00

Wheelie bars . 325.00

Tires front-125 slick 90.00 rear-Goodyear 3341 pro-stock slick 112.00

Chassis total $2649.50 Grand total . $3278.00