The Lost Art of

Cut­ting metal for more speed and bet­ter re­sults

Motorcyclist - - Contents - —Brody Cox

IN THE EARLY 1970s, mo­tor­cy­cle tuners were chas­ing a magic for­mula to im­prove the power and ef­fi­ciency of two-strokes—sim­ple, light­weight en­gines found in many on- and off-road bikes from that era. Ted Boyko be­gan port­ing cylin­ders 45 years ago, when the two-stroke craze was at its peak, and he’s still at it to­day.

“It was all the guys with Yamaha RD350S and 400s,” re­calls Boyko, lean­ing against a wooden work­bench in his well-lit shop, Boyko Rac­ing, in Costa Mesa, Cal­i­for­nia. “That’s when it first went off the hook. Then, you had the RZ350S in the ’80s, which were liq­uid-cooled and even cra­zier.”

Boyko is con­sid­ered an ex­pert at mod­i­fy­ing in­take, trans­fer, and ex­haust ports—the an­gle, shape, and size of which can yield dra­matic changes in en­gine char­ac­ter and per­for­mance. From the fac­to­ries, the former racer says, those crit­i­cal pas­sage­ways are some­times par­tially blocked by casting slag left be­hind by the hasti­ness of pro­duc­tion-line ma­chin­ing pro­cesses.

Boyko out­lines the ba­sics of what many con­sider a dy­ing art. “You want to push fuel to the spark plug quicker with­out ex­haust gases es­cap­ing ex­ces­sively,” he says. “I pol­ish the ex­haust port and the head so that car­bon doesn’t ad­here to them, but if it does, it’s eas­ier to clean off. On the in­take side, a rough sur­face will help at­om­ize fuel and keep it mov­ing. The tex­ture will keep the fuel loose—tur­bu­lent.”

Ev­ery minis­cule bit of metal that Boyko re­moves with his hand­held car­bide-tipped ro­tary grind­ing tool is ul­ti­mately in­tended to im­prove the func­tion and ef­fi­ciency of the en­gine and its com­po­nents.

Point­ing to a freshly mod­i­fied Honda CR500R cylin­der, Boyko says, “One wrong cut, one slip, and I have to eat the cost of this whole thing. It’s def­i­nitely a chal­lenge, but it’s im­por­tant to cater the en­gine to the per­son in con­trol of the throt­tle. Ad­just­ing th­ese en­gines for each in­di­vid­ual’s style can make or break his or her chances for a podium fin­ish. For me, per­son­ally, it’s all about sav­ing pri­va­teers from hav­ing to fork out so much money.”

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