1972 Yamaha TR3
Engine: 350cc air-cooled 2-stroke twin, five piston ports per cylinder, 64mm x 54mm bore and stroke
Claimed Power: 54hp @ 9,500rpm
Top speed: 140mph-plus
Weight (dry): 220lb (100kg)
Fuel capacity: 6gal (23ltr)
A racing motorcycle is interesting, but a racing motorcycle with known history is even more fascinating. In the late Sixties and early Seventies, Yamaha was proving to be a force in the North American go-fast scene with their 2-stroke 250cc and 350cc twins. Often as not, their small-bore 2-strokes were beating 4-stroke motorcycles with double the engine capacity.
That’s where racer Keith Mashburn enters the picture. In the late 1960s, Keith was racing for Yamaha and also working in the company’s race research and development department. And although Keith didn’t know it at the time, he had made history in December of 1967 when he became Yamaha’s first contracted American racer. He signed on as an amateur and was expected to ride many of the tracks in the AMA circuit.
In 1970-1972, Keith Mashburn was pinning the throttle hard on Yamahas, racing in TT, short track, half-mile, mile and road race events. This was the period, Keith explains, when you had to ride in all of the various races in order to vie for an overall national championship.
Part of Keith’s job at Yamaha was to uncrate and distribute motorcycles to racers, including Kel Carruthers, Kenny Roberts and himself, of course. In 1972, he cracked open the crates on a series of Yamaha TR3 production racers that had been shipped to the U.S. from Japan, including one bearing frame number TR3 990101 and engine number R5 990101 — the 101 in the number indicates it was the first TR3 off the production line. He set TR3 101 aside to be his racer for the 1972 season and distributed the rest.
Since 1961 and the introduction of the TD1, Yamaha had offered racing versions of its street bikes. These production race machines were raced by privateers at the club level and also by Yamaha at the national level. Carrying on the tradition of constructing production racers from street machines, the Yamaha TR3 was based on Yamaha’s R5 350cc twin of 1970.
Yamaha’s R5 street bike traced its lineage back to the 1967 YR1 Grand Prix — a 348cc short-stroke, 2-cylinder, 2-stroke. The YR1 was the largest street bike in Yamaha’s 1967 lineup, and it was developed from lessons learned on the track. The 2-stroke twin featured aluminum cylinders with cast iron sleeves and a horizontally split crankcase. With its triple piston ports, squish heads and direct oil injection, the YR1 produced 36 horsepower. For comparison, a 1967 650cc Triumph Bonneville produced 49 horsepower, but where a Triumph had four gears, the YR1 had a 5-speed gearbox.
The YR1 became the YR2 for 1968, then the YR3 in 1969 and finally the R5 in 1970. Production racers followed a similar nomenclature system, but the TR2 racer wasn’t available until 1969, and the TR3 until 1972. The TR2 was Yamaha’s first race engine to use the horizontally split crankcase and sported hard chrome cylinder bores and single ring pistons. New cylinder ports were added, and the heads had a different combustion chamber than the street-legal 2-strokes.
The frame was similar in appearance to a Norton featherbed, with twin upper frame rails emanating from the bottom of the braced headstock. Yamaha telescopic forks took care of the front, with a square-section swingarm with twin shocks in the rear. Brakes were a four-leading-shoe drum up front and single-leading-shoe at the rear.
The Yamaha TR3 was released in 1972, powered by the same 350cc 2-stroke twin with five ports per cylinder and a 64mm x 54mm bore and stroke (the same dimensions as later RD350s). A pair of 34mm Mikuni carburetors metered fuel. The transmission was a 6-speed fed through a dry clutch. The race-tuned 350cc TR3 was making 54 horsepower, and at just 220 pounds dry, the TR3 could be a very fast motorcycle.
Don Emde, racing with support from Team Motorcycle Weekly and dealer Mel Dinesen, won the 1972 Daytona 200 on a Yamaha TR3, and with that win the TR3 became the first 2-stroke and also the smallest capacity motorcycle to win the historic race, making the Yamaha something of a giant killer.
Keith raced his TR3 hard the entire season, working with his close friend and mechanic Sam Yamazaki. The TR3s came from Yamaha equipped with a Camber fiberglass fairing and rear seat hump. 1972 was the first year for the distinctive bumblebee yellow, black and white paint scheme, which was designed and sprayed by Rollin “Molly” Sanders, who also conjured up Kawasaki’s green racing livery and the Lexus logo, among others. Keith’s number 19 was added, and because he never raced with a front fender, the blade was removed.
Keith made a few changes to the Yamaha TR3 over the months he raced. An engineering friend of his father’s with aerospace background built a longer rear swingarm with a splined rear axle to help prevent twisting. Extended Koni rear shocks were added, and Keith switched to a Vesco fairing and seat. Although he didn’t have the success of Emde, during his season aboard the TR3 Keith came in 16th at Daytona, 14th at Road Atlanta, 13th at Loudon and 11th at Indy.
When he finished the 1972 season Keith Mashburn was free to do with the bike as he wished, so he sold it, complete with the original swingarm, fairing, and other bits and pieces. After that, the Yamaha TR3’s fate was unknown until retired racer Mark Seifried was offered an old Yamaha track bike.
“It had been painted blue, white and black, in the same bumblebee paint scheme,” Mark says. “It still had the Dunlop race tires, which had been phased out after 1974, so I knew it was an early bike, but nobody knew just whose race bike it might have been.” Back in 1972, Mark had raced in the novice class while Keith raced in the expert class, so the two were acquainted and spoke from time to time over the years. The Yamaha was just 4 miles from Mark’s home in California.
In 2003 he bought the motorcycle and several boxes of components, including two sets of fairings and tail sections, one of which was yellow. He began some research and, looking closely at the Yamaha and its various parts, Mark began to suspect he’d found Keith’s 1972 race-season machine.
“I called up Keith and said ‘I think I’ve got your bike,’” Mark recalls. “Keith asked me what the serial number was, and when I told him the last three digits he said, ‘That’s my bike.’ Really, that extended swingarm identified the bike, but Keith’s confirmation of the serial number clinched it.”
Mark retired from the track in 1979. A tool and die maker by trade, resurrecting vintage race machines became his hobby, and he has restored several motorcycles. His first, in 1990, was a Don Vesco 1970 Yamaha TD2 250 that had been ridden by Kel Carruthers to a win at Daytona in 1970 in the Expert Lightweight class. He’s not building up a museum collection, and has sold half of the machines he’s finished. “I like to restore them, but once I’m done I’m through and it’s on to the next one — that’s just how I work,” Mark says.
Mark stored “Mashburn 19,” as he refers to Keith’s Yamaha TR3, until 2010 when he started the restoration. He thinks whoever bought the TR3 from Keith must have raced it one or two seasons. The frame wasn’t twisted or bent, but it was cracked at the lower engine mounts — a known issue on the TR3. Once he had it stripped down, Mark welded up the mounts and powder-coated the frame. “It was in poor to fair condition,” Mark says of the bike. “Poor, because the tank was dented and beat up and the Vesco fairing was damaged, but fair because the engine had never grenaded.”
Mark made a decision to restore the Yamaha to the way it would have been prepared for Keith’s first race — without many of the modifications made over the season — and he had some unexpected help when he heard from Sam Yamazaki, Keith’s mechanic in 1972. Stored on a shelf in Sam’s garage were the original cylinders for Mashburn 19. “They put new stuff on every time they went racing,” Mark says. “Bikes ran one or two races, and instead of honing the cylinders and replacing pistons, they’d just replace everything with new because they had access to all of the parts free from Yamaha. Sam had taken the cylinders home, and then offered them to me,” Mark says.
Mark installed new bearings and seals with a rebuilt crank in the bottom end, and also carefully inspected and rebuilt the gearbox. The engine cases are in their natural state while the side covers were painted black, as they were originally. The original cylinders were given a light hone and Mark dropped in new pistons. Keith’s original race chambers were in several pieces, and while Mark says he could have welded them back together, he instead repainted the pipes that came with the project.
Turning to the suspension, Mark machined and installed new bronze bushes in the original swingarm. The stock rear shocks were in good condition, requiring only an oil change, and the fork tubes were in remarkable condition, with the exception of a few minor nicks. The legs and lowers were cleaned and reassembled with new seals.
The wheels were disassembled and the alloy rims cleaned and detailed, while the spokes were given fresh zinc plating. After lacing the rims to renewed hubs, the brake drum surfaces were machined and the backing plates were treated to new shoes. The period Dunlop Racing KR76/KR96 tires that were on the bike when Mark bought it were reinstalled.
Under the oil lid Mark found a paint number and had it cross-referenced by PPG; it turned out to be a commonly available bright yellow. Working in his 1,100-square-foot shop, Mark masked the bodywork to Molly’s original specifications and sprayed the fuel tank, the Camber fairing and the tail section — first laying down the white, then the yellow, then the black. Keith’s number 19 was applied by hand. Fairing specialist Leif Gustafsson at Florida-based Gustafsson Plastics supplied a new clear fairing bubble.
Over the years, Mark has accumulated an inventory of NOS parts for Yamaha race bikes, so new grips, cables and rubber tachometer mounts from his inventory were installed. The finishing touches, though, are the decals on the restored TR3. Keith had a folder full of original decals, which he happily gave to Mark to fully complete the Yamaha.
“I haven’t run Keith’s bike,” Mark says of the finished restoration. “I know it will run, but I have no real reason to fire it up. I know what they sound like. We used to be out on the starting grid with 80 bikes and no earplugs. I’m not really into the noise of them anymore.”
Mark intends to keep Mashburn 19, but Keith admits he wouldn’t mind having it back. “If I could afford to own that bike it would be sitting in my living room — and my wife, Shelby, would approve,” Keith says. “She wouldn’t allow it to be kept in the garage.” MC
Read more about Keith Mashburn in Then and Now: Keith Mashburn.
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