SR Archive: Outrageous! Yamaha TZ750

The nightmare and headaches of an outrageous project

This article was originally published in the December 1996 issue of Sport Rider.

What happens when you combine one part nitro-glycerine in the form of Yamaha’s four-cylinder two-stroke TZ700 and one part TNT in the form of Kenny Roberts? Twenty-two years ago these two explosive agents were brought together and the ensuing blast changed the face of world roadracing forever. The brutish in-line four screamed and squirmed like an angry beast, and not-yet-King Kenny Roberts became its un­disputed master. Previous lap records weren’t broken—they were destroyed, and in the time it took to push-start the nasty Yamaha, everything from MV Agustas to BSA triples to Kawi two-strokes became yesterday’s news. The TZ700, and TZ750 that followed it, pushed roadracing forward like only a 130-horsepower two-stroke could. At the same time, they launched the kid from Modesto, California, to stardom.

Yamaha TZ-750
Yamaha TZ-750Photography by Scott Rathburn

Yamaha’s reign lasted 12 years, from Kenny Roberts’ first test at Daytona in February of ’74 to the day the wailing music died when the AMA pulled the plug on Formula One, replacing it with Superbikes, in 1987. A year before the end I visited Daytona with the express purpose of seeing a TZ750 up close; I would be forever entranced by this evil beast. The F1 class was on its last legs and these warriors were about to be cut from the AMA’s race program, but I had come face-to-face with the legendary, mythical TZ750 and was deeply moved by the experience. Two years later I owned one.

I bought a '78 TZ750 sight unseen from an ex-club racer in Michigan based on the promises this lout made about the bike. He lied. I remember the day the crate arrived, and my glee turning to dismay upon uncrating my purchase. Photographer David Goldman was in town and snapped a shot before pronouncing, "That thing's junk." And so it was. Rust and oil fought for supremacy, the pipes were cracked and incomplete, the windscreen tailored with a chain saw, the wires hanging, the chain missing, the tires torched. I rolled it into the Motorcyclist garage and buried it under a blanket. There it remained for five years.

Yamaha TZ750
From nightmares and headaches hidden under a blanket to one outrageous street bike project.Photography by Scott Rathburn

Somehow, Chris Geiter heard about the TZ. I had met Geiter during our Power of the Poconos feature stories and had developed a cross-country friendship with him, along with enormous respect for his fabricating skills. “Let me mess with that thing,” he would say every few months, and finally his cajoling sprouted an idea that seemed crazy, out­rageous, per­fect. Let’s make it a street bike. Geiter loved the idea, and a week later the bike was dusted off and trucked to Pennsylvania.’

Chassis: Geiter's Headache
The abused and neglected TZ750 left its dungeon to be shipped to Chris Geiter in Allentown, Pennsylvania. Geiter takes over the story from there. "The delivery truck arrived and everyone in the shop was excited. For some reason, the delivery guys were laughing, and when we finally saw the TZ, we knew why. One of the delivery guys asked, 'Should we use the ramp to unload it or just push it off the back of the truck?' Funny guy, but he was right. That thing was junk.

Yamaha TZ750
With the AirTech bodywork stripped, there’s not much to this TZ. The billet aluminum footpegs and brackets were designed by Southwest Motorsports for a TZ250.Photo Courtesy of Nick Cedar

“This wasn’t going to be a two-month project,” Chris remembers. “Not only were parts missing, abused or rusty, but there were some major problems, like the complete degradation of the exhaust system and the cracked frame. No, make that broken frame. Just under the steering head, the two frame down­tubes were cleanly broken. I didn’t know where to start. I didn’t know if I should start.” But after years of building custom Harleys, GSX-Rs and CBRs, the tiny-but-menacing TZ captured Geiter the same way it had captured me and thousands of others. It was pure, simple and potent, even in its less-than-pristine state.

Digging In:
Geiter yanked the in-line, four-cylinder engine and sent it to Steve Biganski at Extreme Lean in California (more on that later). The Dymag wheels needed serious attention and were sent to Connecticut Cycle Refinishers for paint and a complete refurbishing of the notoriously porous magnesium rims. With the frame stripped, Geiter took a ride up to Precision Chassis Fab­rication to seek possible solutions to not just the broken downtubes, but to additions necessary to mount a battery, lights and horn. Meanwhile, Morgan Racing was brain-storming a mounting system to match the exhaust pipes to a set of carbon-fiber mufflers from Carbon Tech.

Chris Geiter’s mind was working overtime on the spindly stock front end. “I did a little measuring and found that a set of RC30 triple clamps would fit the frame, and a pair of ZX-7 fork tubes would slip right in.” This combination illustrates the beauty of Geiter’s unique touch of combining parts into a homogeneous whole.

Yamaha TZ750
The Dymag 18-inch wheels, Toomey pipes, aluminum swingarm and Lectron carburetors were popular period upgrades for the TZ750, and we added PM brakes, Dunlop radials, a Street and Competition steering damper and a ZX-7 fork to create our street version.Photo Courtesy of Nick Cedar

While the triple clamps were being finished, the ZX stock rear monoshock and fork were sent to Lindemann Engineering for a rebuild (the rear shock) and a revalving, because the ZX fork would now be dealing with a bike approximately 130 pounds lighter than a ZX-7.

The AP Lockheed calipers that came on the front of the bike were replaced with Performance Machine billet four-piston calipers and 310mm full-floating rotors because the only way to enjoy a fast bike is to have good brakes, and Geiter and Biganski planned to build a fast TZ. A call to Florida produced a tinted windscreen from Gustaffson Screen, purveyors of every weird windscreen known to man; they had the TZ screen in stock!

Yamaha TZ750
The RC30 triple clamps hold revalved ZX-7 fork tubes with Yoyodyne titanium fasteners. The machine work was performed by JVE Limited, including the immaculate aluminum top nut, and the master cylinder came from a CBR900RR.Photo Courtesy of Nick Cedar
Yamaha TZ750
Chuck Odom at CBO Products sells a kit to mount the Avocet bicycle speedometer on motorcycles (right), an excellent solution for most project bikes.Photo Courtesy of Nick Cedar

Momentum Increases
The frame sat on Geiter's bench, half the size of a normal four-stroke 750 frame, and two-stroke fever bit the fabricator hard. The Lectron carburetors were up at Fast by Gast getting a complete rebuild, including cables, and Indigo Sports provided a shift lever and some trick aluminum hardware for the mounting of the bodywork. Geiter trashed every piece of stock bodywork except the aluminum fuel tank, which he stripped, and added a quick-fill dry brake from Lockhart Phillips to replace the old rotted one. Kent Riches at AirTech suggested an interesting solution: a TZ500 tailsection mated with a TZ750 fairing with a single headlight hole, all made of fiberglass. The 500 rear section was significantly more attractive than either the 750 "ducktail" or long seat; some welding by Precision Chassis Fab located the Dzus quick-release points while a few hours of aluminum whittling produced a sano upper fairing mount.

At this point, Geiter contacted Yoyodyne Titanium in Roselle Park, New Jersey, because one of the true beauties of the two-stroke genre is light weight, and Geiter wanted to ban steel from the machine. Months of diagrams and phone calls followed, resulting in titanium and aluminum replacing steel in the engine-mount bolts, triple-clamp bolts, both axles and various and sundry fasteners throughout the machine. As you may have guessed by now, this wasn’t a budget project or “10 ways to improve your motorcycle for $10.99.” This was a once-in-a-lifetime chance to build a dream bike, and dreams should be done in full Technicolor.

Yamaha TZ750
The south end of a north-bound TZ750 is a glorious sight to behold, and the music that these pipes make is heaven for a two-stroke enthusiast. Lockhart Phillips provided the turn signals, and the Novella Gel battery (located inside the tailsection) can be mounted in any position.Photo Courtesy of Nick Cedar

Engine: Biganski's Nightmare
As Geiter compiled parts and pieces in Allentown, Steve Biganski uncrated the engine in Los Angeles. Biganski reported, "No wonder the chain was missing, the guy who sold the bike didn't want you to try and start it. It might have run…for about 30 seconds. Some blind guy must have trued the cranks, and when the genius bolted together the cases, he didn't align one of the alignment pins correctly and pushed it out the bottom of the engine. The case mating surfaces were all but ruined and needed some serious attention. That thing was junk."

It wasn’t until we spoke with Scott Guthrie that we had confidence in ever completing the engine. From Guthrie, we met Steven Wright, owner of both TZ750 dirttrackers ridden by Stevie Baker and Kenny Roberts and a few other delectable morsels of speed. Through these two, and other gurus such as Don Vesco, Jim Reed and Kel Carruthers, Biganski and I assembled the parts needed to begin the rebuild­ing process.

I certainly picked the right guy for the job, and not just because he’s tuned my TZ250s for the last five years. In the late ’70s and mid-’80s, Steve Biganski raced TZ750s on the national circuit, and his enthusiasm for these machines kept him going in the face of almost insur­mountable odds.

Yamaha TZ750
The Uni Filters plugged onto the back of the Lectron carburetors extend piston and crank life to real-world proportions. The single rear shock was rebuilt by Lindemann Engineering but provides little external adjustment.Photo Courtesy of Nick Cedar

Finishing Touches
While Biganski herded the engine together, Geiter sent all the bodywork to Elmer Blackstock for prep and paint. Geiter and I discussed the colors for hours on the phone and finally resisted the temptation to go yellow and black, choosing instead the current Yamaha racing colors of blue and silver with some orange thrown in. Blackstock nailed the paint, and after Geiter layered on the stickers custom-made by Tapeworks and bolted on the beauti­fully restored Dymag wheels from Connecticut Cycle Refinishers (with Dunlop K591s), the bike was at last complete after two years of intense work. It's hard to say which piece Geiter is most proud of; while the pipe restoration and front end combination merit special mention, Geiter said, "I'm most proud of the way it all came together in such a perfect package. All those parts just work together."

Yamaha TZ750
The TZ adorned the dining room during the Sport Rider Christmas party while Chris Geiter leans against the bike he built. Too bad he returned to Allentown before we got it running!Photo Courtesy of Nick Cedar

So, Let's Ride It
Geiter shipped the finished bike back without getting it running because we wanted to enter it in the Cycle World motorcycle show in Anaheim. And that may be the only time the TZ will be presented as a show bike because we built it to ride. It took Biganski about 30 minutes to diagnose an electrical problem (the pick-up plate was mounted 180 degrees backward), and two minutes later I was cruising around the block in the dead of night on a fully lighted TZ750 street bike. A week later we unloaded it at Kenny Roberts' ranch for the official debut.

Can you think of a better spot in which to debut a TZ750 street bike? After a few tentative trial runs, I twisted the throttle hard on the road in front of the ranch. Despite the tall gearing (AFAM 15/40 sprockets with a Tsubaki 520 O-ring chain), first gear was practically useless and second gear would snap into a wheelie with anything over half throttle. Third gear would power-wheelie and the bike would continue to dance in fourth. Wow. Everything I’d heard about the TZ750 was true. I had certainly ridden faster bikes, but the two-stroke power and TZ riding position was an unbelievably perfect feeling. And then Kenny rode it.

Yamaha TZ750
King Kenny Roberts straddles his TZ700 at Daytona prior to the three 500cc World Championships he would win for Yamaha. Kel Carruthers stands beside him and actually rode the TZ700 in June of ’73 in Japan. “It tried to spit me off in every corner,” Kel remembers. They were fast and evil.Photo Courtesy of Nick Cedar

Kenny cruised back up the mile-long driveway and yelled over the grum­bling TZ, “Grab your cameras, I’m doing some wheelies down here.” With that, he was off again and we followed in the car. For the next 20 minutes King Kenny whipped back and forth in a series of second- and third-gear power wheelies just like the old days at Laguna Seca. Unbelievable.

Yamaha TZ750
Racing fans will never forget Dale Singleton’s 1981 Daytona 200 win on (what else) a Yamaha TZ750. Can you see the chunked front Goodyear?Photo by James Huff

Of course, things can’t ever be that perfect, so it was no surprise that the TZ had some teething problems. Unfortunately, it didn’t want to stay in first gear, so we pulled the engine again and split the cases, sending the gear to Murdock Racing Enterprises in Florida for some significant machining and heat treatment (remember, there are no new TZ parts down at the dealership). Once back together, the bike has proven a ball to ride, feeling significantly smaller than a CBR600F3 and surprisingly fun in the corners. The racing pedigree comes through sharply with unrivaled traction feedback and relatively heavy steering despite the light weight (339 pounds with no fuel); the bike’s beyond our brightest hopes.

Yamaha TZ750
Greg Hansford’s Kawasaki feels the pressure of Takazumi Katayama’s TZ750 (349) while Gene Romero runs his Don Vesco–tuned TZ in for a closer look. The TZs were unbeatable and unbreakable, and remained that way for a decade, winning Daytona from 1974 to 1983.Photo Courtesy of Nick Cedar

Money, Sweat, and Time
You don't want to know the time and money invested in this outrageous project (well, maybe you do, but we aren't telling), but the cult following the TZ750 enjoys is certainly worth mentioning. The purposeful purity of this machine has been attracting motorcyclists for more than two decades, and thanks to Chris Geiter, Steve Biganski and the American sport-bike industry, the TZ750 will live on, 10 years after the AMA pulled the plug on Formula One.