The 145mph T2750 Flat Tracker BANNED BUT NOT FOR­GOT­TEN

Side­ways scrub­bing. Look­ing for trac­tion. Rid­ing what is one of the nas­ti­est ma­chines ever made. There’s a rea­son why many in the rac­ing world love and fear these things. Not least of all be­cause of how they bite. And how of­ten they can.

Classic Racer - - NEWS - Words: Terry Steven­son Pho­tog­ra­phy: Kenny Roberts, Dan Ma­honey archives ,terry Steven­son

The mo­tor­cy­cle world stopped when Kenny Roberts climbed aboard Ray Abrams’ Yamaha TZ750 flat tracker at In­di­anapo­lis in 2009. He rode it like he stole it dur­ing that fa­mous Satur­day evening demon­stra­tion dur­ing the Indy Motogp week­end – as only the great King Kenny knows how. But that wasn’t his first time at the Indy Mile on a TZ750 flat tracker. His first ap­pear­ance be­came fa­mous af­ter Roberts pro­claimed, “They don’t pay me enough to ride that thing!” It was a com­ment that later helped AMA officials decide to ban it from com­pe­ti­tion. The saga started in early 1974 when Steve Baker and me­chanic Bob Work stopped by to visit Doug Sch­w­erma at Cham­pion Rac­ing Frames, in Cal­i­for­nia. The pair were on their way home af­ter pick­ing up the dis­play Yamaha TZ750 road racer af­ter the Ana­heim dealer show. One idea lead to an­other and Sch­w­erma, who was al­ready mak­ing Cham­pion frames for AMA flat track­ers, mea­sured it up and com­pared it side by side with an XT650/750 Cham­pion frame to see if it all fit­ted. It did, how­ever he had to wait quite some time be­fore he got an en­gine to build a frame around, and when he fi­nally did, in 1975, it was his­tory in the mak­ing. Renowned race bike builder Ray Abrams, of A&A Rac­ing in San Fran­cisco, built up the pro­to­type us­ing a Cham­pion chas­sis, which en­joyed sim­i­lar frame di­men­sions to the 650, but he al­ready knew its po­ten­tial! “There used to be a quar­ter-mile drag strip across the bay in Freemont, and I took the bike over there when it was still in the road race frame and it turned 138mph in around 9.5sec in its stock form. So we knew it was go­ing to be a whole lot faster!” Abrams says, laugh­ing. “It was re­ally go­ing over­board de­vel­op­ing some­thing nasty be­cause it was a whole lot faster! Al­most ev­ery­thing was dif­fer­ent. The tyres didn’t work as well be­cause we were putting more power through them, but we did what we were ca­pa­ble of do­ing at the time.” The pro­to­type was built for the Mile ovals but was tested by Rick Hock­ing at the As­cot Half Mile in Gar­dena, Cal­i­for­nia, in 1975. The prob­lem was that by 1975, Har­ley-david­son’s al­loy XR750 had be­come more com­pet­i­tive, which left the XT650/750 un­der­pow­ered – and be­hind on the long straights. The TZ750 flat tracker was the ob­vi­ous in­stant so­lu­tion, plus most en­gines came from read­ily avail­able donor road race ma­chines sup­plied whole, by Yamaha. In­ter­est in this big-balls idea in­creased af­ter Hock­ing set the third-fastest time dur­ing As­cot on the pro­to­type, and it wasn’t sup­posed to suit half-mile tracks. Abrams again: “My bike was orig­i­nally built for Hock­ing. I don’t think he com­plained about any­thing. As­cot is a per­fect place for a mo­tor­cy­cle, as you can spin the rear wheel and it’s eas­ier to con­trol. I don’t think there were any ma­jor prob­lems there, and Rick was a guy, like Kenny, who was ca­pa­ble of rid­ing any­thing you put un­der­neath him!" Five other TZ750 flat tracker frames were made for 1974 AMA Grand Na­tional cham­pion Kenny Roberts, Steve Baker, Randy Cleek, Skip Ak­sland and Don Vesco. This was at a time when the Grand Na­tional con­sisted of sev­eral dis­ci­plines, where Yamaha rid­ers dom­i­nated the road rac­ing sec­tor with the mighty TZ750, and Har­ley-david­son on the flat tracks. Abrams con­tin­ues, “I was in­volved with the whole project as we sup­plied a lot of the parts for all of them. Five of us in­di­vid­u­ally built them. They were all built by dif­fer­ent peo­ple. We talked a lot and we did a lot of the same things at the time. We built the race wheels here for all five bikes. There’s a guy in Los An­ge­les who has copied them now and built two or three more.” The five TZ750 flat track rid­ers had to wait un­til the first mile event at In­di­anapo­lis, on Satur­day, Au­gust 23, 1975. Af­ter a string of me­chan­i­cal is­sues, de­fend­ing champ Kenny

Roberts was trail­ing se­ries leader Gary Scott, and was desperate for vic­tory. Kel Car­ruthers was Roberts’ me­chanic for many years, and re­calls, “We built the bike for Kenny in my road race shop us­ing one of our spare stock en­gines. Indy was the first time Kenny saw the bike. We broke the footrest in prac­tice and I made some mods be­fore the semi and again be­fore the main event.” Kenny Roberts re­calls that first out­ing: “The first time I came out of turn four on the first lap, I moved on the han­dle­bars to get some grip and the thing jumped into the air. And I damn near looped it! I thought ‘Holy shit’ this thing is go­ing to hurt me if I don’t pay at­ten­tion. From that point on I paid it a lit­tle bit more at­ten­tion.

“If you rode it slowly it was no prob­lem, it was a joy to ride. If you wanted to ride it fast there was a prob­lem be­cause the thing spun the tyres so eas­ily. You made up a lit­tle bit of time on the straight­away and then ev­ery­thing would look good com­ing out on the back or front straight and then it’d just light up, and you were done. So that was the hard part, just get­ting it to hook up. “There was a kill but­ton on the han­dle­bar that killed one cylin­der, but that didn’t work [for me],” Kenny laughs. “Nor­mally I would pull my hand off the damned thing be­fore I should have, and that would just put 30 more horse­power into it! So it would just whip side­ways. Some­times I’d use it and some­times I wouldn’t, it didn’t re­ally help that much. The TZ750 just wanted to spin the wheels as soon as you opened the throt­tle, so whether you had two cylin­ders or four cylin­ders, when you started open­ing the throt­tle it was still go­ing to spin. “The prob­lem was that the Har­leys were do­ing about 30mph less – one time I went into turn one and Gary Scott and Mert Lawwill were rac­ing each other and luck­ily Mert went to the out­side. Had Mert stayed where he was when I pitched it in, I would have taken him out! And my­self, or course.” Based on gear­ing and rev counter nee­dle, KR said he was trav­el­ling faster than 145mph down the straights. “I ac­tu­ally split both of them go­ing side­ways about 30mph quicker. That was the down­side of the whole thing – if some­body was in the way you weren’t go­ing to miss them." But that’s not all King Kenny learned that night. “I had to ride the semi and that’s

when I de­cided I would shift it (change gear). Be­cause when we shifted, it would pause just enough to get a lit­tle grip. I spoke with Ak­sland [Skip], he was third in his heat race and made the main event, I said, ‘Skip, you need to shift it.’ He said, ‘No, no, mine works good.’ I passed him in the main event so I lapped him!” Kenny chuck­les. He won the first of the two semis and qual­i­fied for the fi­nal. “So I tried that in the semi and I won, it put me last on the sec­ond row on the line. That is where I started.” In the fi­nal, Roberts came from dead last to make third po­si­tion ex­it­ing the last cor­ner, with ex­pert Har­ley-david­son rid­ers Corky Keener and Jay Spring­steen ahead. KR again: “It was on the amount of grip and you couldn’t fol­low a Har­ley in the mid­dle of a cor­ner be­cause it spun too much. So it was high, wide and hand­some the whole night, and as soon as I got a berm built up next to the hay bales I started pass­ing ev­ery­body. Un­til then I would pass them and they’d pass me back the next cor­ner, so then I’d pass them on the next straight. By the time I got to the mid-pack I’d started to build a berm. It was clear on the out­side be­cause no­body but me was rid­ing there, and that’s how I was able to start pass­ing peo­ple, and bet­ter peo­ple. “I thought I got third. For some rea­son I had a great hook-up – I don’t know how, as the tyre was half there as it’d chun­ked most of it off, luck­ily it didn’t go flat. I had hay bale wire on it from tap­ping the hay bales, so I came off that cor­ner and I thought, ‘Man, I’m go­ing to get third.’ Then I grabbed a gear, fifth, and went, ‘Wow, s*** I’m go­ing to get sec­ond!’ I damned near hit Spring­steen, I came on him so fast and so abrupt I swerved to miss him, I damn near hit him. Then I thought ‘There’s the start/fin­ish line,’ – I won! “It was just the strangest thing, for some rea­son that last lap it just hooked up and I came off that last cor­ner like it was a four-stroke.” Two weeks later the TZ750 flat tracker turned out to be use­less at the Syra­cuse Mile, as the track con­di­tions didn’t suit either TZ750 or Kawasakis H2R two-stroke due to wheel­spin on the slip­pery hard sur­face. Few stro­kers made it past early prac­tice – Roberts found he could lap two sec­onds quicker on his XT650/750 but, the less pow­er­ful Yamaha suf­fered yet an­other me­chan­i­cal fail­ure in the fi­nal. Roberts’ TZ750 flat tracker was al­tered af­ter Syra­cuse, where it strug­gled on a sur­face more suited to the high-torque Har­leys. Car­ruthers moved the en­gine for­ward and lower in the frame to help keep the front down. He turned the cylin­der heads 180 de­grees so the wa­ter hoses and cou­plings didn’t get in the way of the front down­tubes. He then fit­ted road race wheels with hand-grooved ‘wet’ road race tyres, which later be­came the pre­de­ces­sor of the cur­rent flat track tyre de­sign. In the end they didn’t help at the San Jose Mile due to con­stantly chang­ing track con­di­tions that went from wet to dry. KR had his XT650/750 and the TZ750 to choose from, and there was a lot on the line, as Gary Scott would strug­gle to get a top 10 at the up­com­ing On­tario road race.

KR went with the more pow­er­ful TZ af­ter prac­tic­ing on the twin, as did the other three TZ750 rid­ers in at­ten­dance. Steve Barker went road rac­ing that day. Re­mem­ber­ing they had no time for test­ing, af­ter a tank-slap­ping prac­tice lap KR hit the wall and dam­aged his rear brake and footrest, which were found among the spec­ta­tors and then re-welded. De­spite the is­sues and be­ing in pain, Roberts man­aged to qual­ify the bike in sixth po­si­tion, be­hind H2R mounted Scott Brels­ford. Each won a heat race to make the fi­nal, where three TZ750S, an XT650/750, and a pair of H2RS where pit­ted against 11 Har­ley-david­sons. But all eyes were on the Roberts vs Scott bat­tle. Roberts had tried dif­fer­ent lines look­ing for trac­tion and race op­tions but his soft tyres were chunk­ing, forc­ing the team to risk an un­tried, hard com­pound slick with fewer grooves, but the big TZ sim­ply spun its rear wheel in the fi­nal.

Chip Hen­nen was there. “You missed one of the most spec­tac­u­lar events you ever could have wit­nessed when these bikes were run­ning, and this bike at the San Jose Mile with the H2RS, the ones that Erv Kanemoto built, it was spec­tac­u­lar, un­be­liev­able! The stands were ab­so­lutely packed and ev­ery­one stood up at the start and they stood the en­tire race.” Roberts again: “Af­ter Syra­cuse we put 18in rain tyres on, and that’s what I used at San Jose, and I won the heat race. The prob­lem was that it chun­ked the tyre. I had tested an in­ter­me­di­ate cut slick in prac­tice, when it was bare. I thought if the track black­ens up, that cut slick is go­ing to be miles bet­ter. In the main event the slick never hooked up, it was just the wrong com­pound, so it never got hot. There­fore it just spun all the time.” Roberts fought for con­trol and dropped from a brief fourth early on with ob­vi­ous tyre is­sues, he was 12th mid-race, and fi­nally pulled out of the race al­to­gether with Scott lead­ing. “In the main event I thought ‘you poor bas­tards, you’re not go­ing to see which way I went!’” Kenny says, still laugh­ing. “And it was a dis­as­ter. They brought the black flag out just as I was pulling in.” The cham­pi­onship was over, and shortly af­ter­wards so were the TZ750 and H2R flat track­ers. Don Vesco still hadn’t built his TZ750 flat tracker by this stage. Some of the TZ750 flat tracker en­gines were re­moved, so the rid­ers could use the mo­tors in their road race TZS at On­tario, on Oc­to­ber 5. Abrams re­flects, “Hock­ing rode the Indy, Syra­cuse & San Jose Miles on the TZ750, how­ever with no prior test­ing, Roberts was the only rider who put in top re­sults. We only raced them for two or three races. Rick never set the world on fire on mytz750.”

Car­ruthers and Roberts were at the AMA rules com­mit­tee meet­ing where the 20 mem­bers voted for a min­i­mum pis­ton dis­place­ment of 335cc, and max­i­mum of two cylin­ders on either two or four-stroke en­gines. Car­ruthers says, “I voted to ban the bike. It was just one more bike some guys would need to run the se­ries, but dirt track was mainly a Har­ley deal and it was just bet­ter to leave it as is. I think we did the right thing and left the se­ries as it was. I be­lieve if we had been able to build our own com­plete bike and with bet­ter tyres Kenny could have won all the Miles the next year. If we had run the bike the next sea­son, Goodyear would have made the rain tyre in dif­fer­ent com­pounds for us.” Roberts held the same opin­ion: “I voted to ban it. That wasn’t the right mo­tor­cy­cle for its time be­cause it was go­ing to kill some­one, and I didn’t want that to be me! If you were to turn 10 of them loose on a race­track, the guy who was prob­a­bly go­ing to get hit was me. I think had we not banned it, it would have won all the Miles with the technology of the tyres com­ing along, but at that time, with the tyres we had, they couldn’t have won the race.”

Above: KR just be­fore his first ride – the Indy Mile. Ma­hony Photo Archives.

Right: Ken Roberts – TZ750 – Del Mar 1999, Ma­hony Photo Archives.

1 Ken Roberts,tz750; 62 Corky Keener; 42 Steve Morehead – San Jose Mile – Ma­honey Photo Archives.

Kenny Roberts rac­ing Yamaha XT650-750 flat tracker. Art­work. KR col­lec­tion.

Above: The world’s most fa­mous mo­tor­cy­cle en­gine, four-cylin­der, two-stroke.t Steven­son Photo.

Left: Get­ting TZ750 down,t Steven­son Photo. Above: Four cylin­ders equals four wide air fil­ters, which get in the way.t Steven­son Photo. Left: Kenny Roberts rac­ing Yamaha TZ750 flat tracker. KR col­lec­tion.

Above: Ray Abrams with his TZ750 flat tracker that KR demon­strated in 2009 and Rick Hock­ing rode in 1975. T Steven­son Photo.

Left: TZ750 flat tracker, rear end. T Steven­son Photo.

The bike KR rode at the Indy demo in 2009.T Steven­son Photo.

Left: Ray Abrams’ Yamaha TZ750 flat tracker en­gine. T Steven­son Photo.

Right: Montessa fuel tank from Kenny Roberts’ first flat tracker. T Steven­son Photo.

Above: Ray Abrams rid­ing up the road.t Steven­son Photo.

Be­low: 1 Kenny Roberts,tz750 – San Jose Mile – Ma­hony Photo Archives.

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