Yamaha RZ350 Wet and wild

Old Bike Australasia - - CONTENTS - Story and pho­tos Jim Scays­brook

When Yamaha trot­ted out the RD350LC at the Paris Mo­tor­cy­cle Show in 1979, it was hailed as a mir­a­cle of modern en­gi­neer­ing – a wa­ter-cooled twin cylin­der two-stroke. But it wasn’t that rev­o­lu­tion­ary, af­ter all, Scott built the same thing more than 50 years ear­lier. It’s just that the ‘LC’ (the RD bit was a tilt to the now-de­funct air-cooled RD range which had run up the white flag in the bat­tle against ever-tougher emis­sion laws) was such a com­plete pack­age – the prodigal son of the rac­ing TZ sta­ble that had pow­ered pri­va­teers and works rid­ers alike since 1972, and with­out which, rac­ing would have strug­gled to sur­vive. Nat­u­rally, this point was not lost on le­gions of as­pir­ing play rac­ers, who saw the new RD350LC as the an­swer to their prayers – a week­day ride that could more than hold its own on the track on week­ends. Soon, the grids were full of them.

As shown in Paris, the LC (Liq­uid Cooled) sported the Monoshock can­tilever rear sus­pen­sion orig­i­nally con­ceived by the Bel­gian de­signer Lu­cien Tilkins, and which had graced the TZ range since the C model of 1975. The new road­ster sported a sin­gle disc brake up front and a drum rear brake. It took a few months longer (un­til mid 1980) be­fore the model be­gan ap­pear­ing in show­rooms in Europe, in both 250cc and 350cc form, and with twin front discs, where they were ea­gerly snaf­fled up. But the 350 in par­tic­u­lar was not with­out its prob­lems, which be­gan to show up im­me­di­ately, es­pe­cially un­der rac­ing con­di­tions. Vi­bra­tion was the main cul­prit, caus­ing ex­haust pipes to crack and ex­haust mount­ing studs to break off. There were also per­sis­tent mid-range per­for­mance is­sues – a com­bi­na­tion of cylin­der de­sign and car­bu­ra­tion set­tings, with both these orig­i­nal com­po­nents re­placed in the next model, along with a re­designed reed valve and a new de­sign of oil pump. Get­ting the ex­pan­sion cham­ber ex­haust to stay in one piece took a lit­tle longer. The 350 went on sale in Aus­tralia in 1981, priced at $2099, and con­tin­ued un­til 1986, dur­ing which time it sub­tly evolved into the form of the bike fea­tured on these pages. Again, it was US emis­sion laws that sounded the death knell. In fact, the RZ350 (as it was sold in US) did not ap­pear in the Amer­i­can mar­ket un­til 1983, and only then with the ad­di­tion of a cat­alytic con­verter in each muf­fler of the ex­haust sys­tem, and with no ad­just­ment pos­si­ble within the car­bu­ret­tors to de­ter home tuners from fid­dling with the fac­tory set­tings. When com­bined with oxy­gen, the con­verter es­sen­tially ig­nited the un­burned fuel mix­ture that had passed through the en­gine. In Cal­i­for­nia, mea­sures went even fur­ther, with a third con­verter in the header pipes and a car­bon can­is­ter in­side the fuel tank to cap­ture vapour be­fore it reached the at­mos­phere. For the 1980 Grand Prix sea­son, Kenny Roberts’ works YZR500 was fit­ted with what Yamaha called YPVS – Yamaha Power Valve Sys­tem – a ro­tat­ing cylin­der fit­ted across the en­gine’s ex­haust ports which was con­trolled elec­tron­i­cally to vary the port tim­ing and in­crease power and torque – and burn the mix­ture more com­pletely. As revs in­creased, the en­gine’s CDI unit al­lowed the valve to ro­tate to a fully open po­si­tion at max­i­mum revs. With the Ja­panese ‘big four’ all pro­duc­ing road-go­ing two strokes, vari­ants of the YPVS sys­tem caught on rapidly from the time it first ap­peared on the re­vamped LC mod­els in 1983. The wa­ter-cool­ing of the RD/LC was a big sell­ing

point, with finer tol­er­ances achieved as a re­sult of a more sta­ble en­gine tem­per­a­ture. The first model RD350LC was not fit­ted with a ther­mo­stat how­ever, and in cold Euro­pean weather, had trou­ble reach­ing an op­ti­mum op­er­at­ing tem­per­a­ture – a prob­lem many rid­ers ad­dress by the ex­pe­di­ent of ap­ply­ing tape to the ra­di­a­tor to raise the tem­per­a­ture. In 1983 a ther­mo­stat was fit­ted, which cured the ail­ment.

En­ter the RZ

Pretty much ev­ery­one ex­pected the RD250/350LC to be the last gasp of the per­for­mance two stroke, but they were wrong. In 1983, Yamaha pulled a rab­bit out of the hat with a sub­stan­tially restyled ver­sion, now called the RZ350K in Aus­tralia to co­in­cide with the model’s re­lease in USA. Far from be­ing a cos­metic makeover of the LC, the RZ was al­most all-new in all the im­por­tant ar­eas; en­gine,

frame, sus­pen­sion, brakes. Be­gin­ning with the pow­er­plant, the tra­di­tional 64mm x 54mm bore and stroke, which harked back to the R1/2/3 days of the mid-six­ties, re­mained, but it had grown teeth, with power up from 34.5 kW (47hp) for the RD350LC to 43.5kW for the RZ350 (58.3hp) – that’s nearly 25%. The en­gine it­self was new from the crank­case up, with the ob­vi­ous ad­di­tion of the YPVS sys­tem. Gain­ing this sort of power from a con­ven­tion­al­ly­ported en­gine would have meant sac­ri­fic­ing large chunks of bot­tom and mid-range per­for­mance, but the new sys­tem de­liv­ered tractabil­ity pre­vi­ously un­known in per­for­mance two strokes. The valve re­mained closed un­til around 3,500 rpm, and was fully opened by 6,000. Red line was at 10,000 rpm but the power dropped off sharply be­yond 9,500. Max­i­mum torque of 35.8Nm oc­curred at 8,500 rpm, and there was no trace of the LC’s no­to­ri­ous flat spot at 5,000 rpm – the RZ pulled strongly from 4,000 all the way to the red line. The RZ used sep­a­rate seven-port bar­rels (like the rac­ing TZ) (whereas the LC used a sin­gle block) with twin 26mm Mikuni carbs with reed valves. Chas­sis-wise, the RZ350 fol­lowed the ba­sic LC de­sign, but with larger di­am­e­ter tub­ing and a wider cra­dle with more ef­fec­tive cross brac­ing and gus­set­ing. The en­gine was rub­ber mounted at the front, re­duc­ing the vibes reach­ing the rider via the han­dle­bars. Front forks car­ried air as­sis­tance (with­out a bal­ance tube), but the gasoil ‘Monocross’ sin­gle rear unit (lo­cated un­der tank via a ris­ing rate link­age) was non-ad­justable for damp­ing, with five po­si­tion spring preload ad­just­ment. The spring ten­sion was ad­justed by re­mov­ing the right side panel and turn­ing a toothed-belt pul­ley with a span­ner from the tool kit. The RZ frame used a steeper rake of 26 de­grees (1 less than the LC) with less trail. To mol­lify the quick steer­ing, the wheel­base grew from 1360mm to 1385. New style wheels (from the four cylin­der XJ900) added a lit­tle more weight.

The RZ’s styling was also a far cry from the con­ser­va­tive LC. In keep­ing with the look of con­tem­po­rary Grand Prix bikes, the fuel tank fol­lowed the line of the top frame tube to­wards the swing­ing arm pivot, with a small belly fair­ing en­clos­ing the messy part of the en­gine (at least on a two stroke) and a bikini fair­ing shroud­ing the han­dle­bars and con­trols.

End of the line

As the noose tight­ened on two strokes in the USA, the days of the RZs were num­bered, and the axe fell at the end of 1985 when it be­came clear that im­pend­ing tight­en­ing of re­stric­tion would make the RZ (and all other two stroke road bikes) his­tory from 1986, at least in the key Cal­i­for­nian mar­ket. But the story did not quite stop there. Yamaha shifted pro­duc­tion to its sub­sidiary Yamaha Mo­tor Da Ama­zo­nia in Brazil and con­tin­ued pro­duc­tion there from 1986 with what was of­fi­cially termed the 1YH ver­sion. This used alu­minium can muf­flers at­tached to the ex­pan­sion cham­bers, TZ style, with a half fair­ing. From 1988, the model, mar­keted again as the RD350LC, con­tin­ued in pro­duc­tion in Brazil with a full fair­ing, which in 1991 in­cor­po­rated twin head­light. With ever-in­creas­ing anti-pol­lu­tion re­stric­tions sap­ping per­for­mance, pro­duc­tion ceased in 1992.

Twice bit­ten

At the Shan­non’s win­ter auc­tion in Syd­ney, Steve Ashke­nazi bought a 1985 model RZ350N. He didn’t mean to; it just hap­pened that way. Steve was at the auc­tion to sell his Kawasaki H2, which achieved a re­mark­able $33,500, so, flushed with cash and more than a lit­tle sur­prised, the very next lot to go un­der the ham­mer caught his at­ten­tion. Back in his rac­ing days, Steve pro­gressed from a Suzuki X7 to an RD250LC in time for Bathurst in 1981, along with most of the field in the boom­ing 250 Pro­duc­tion class. “I reckon there would have been some­thing like 60 of them (LCs) on the grid at Bathurst,” he re­calls. It was the year of the RD250LC at Bathurst, when West Aus­tralian Michael Dow­son led home Ashke­nazi and Ge­off McEwin (all on the new Yama­has) and in the process carved a stag­ger­ing 9.3 sec­onds off his own lap record, set the year be­fore on an RD250F. It was an em­phatic demon­stra­tion of the quan­tum leap in per­for­mance made by the new wa­ter-cooled pack­age.

“I re­ally did not in­tend to buy any­thing at the auc­tion,“says Steve. “In fact, quite the op­po­site as I have sold a few bikes re­cently to cre­ate some space. But this RZ350 was ab­so­lutely per­fect, every nut and bolt looked like new, and it was pretty much iden­ti­cal to the RZ250 that I fin­ished my rac­ing with. It was meant to be: I even had a brand new rear lug­gage rack at home for this model! Through our shop (Mack­lin Mo­tor­cy­cles at Mi­randa in Syd­ney’s south) we sold heaps of LCs and RZs in the ‘eight­ies, but mainly 250s be­cause of the ridicu­lous regis­tra­tion fees in NSW for bikes above 250cc. The 350 had about ten more horse­power, but even that wasn’t enough to jus­tify pay­ing triple the regis­tra­tion each year.”

In the sad­dle

The mo­tor­cy­cle that Steve pur­chased at auc­tion is a 1985 US model, which has US-made ex­haust pipes fit­ted with alu­minium si­lencers, and with­out the cat­alytic con­vert­ers. Nev­er­the­less it runs beau­ti­fully, as I dis­cov­ered one sunny day on the NSW South Coast when Steve gave me a chance to sam­ple the bike on the glo­ri­ous roads around Kiama. He told me that de­spite hav­ing the US-style carbs which have a link­age-type set up in­stead of in­di­vid­ual ca­bles to lift the slides, it car­bu­rates ex­tremely well, and he wasn’t kid­ding. “When the RZs came out in Aus­tralia in 1983, they had none of the pol­lu­tion stuff on them that the US mod­els had to have, so they had huge horse­power,” said Steve.” The US ex­haust pipes were ex­tremely heavy with the cat­alytic con­vert­ers.” The RZ feels amaz­ingly light and nim­ble – it brought back mem­o­ries of my days on TZ350s – and it will take off with very lit­tle throt­tle. There’s ab­so­lutely none of the old two stroke bug­bear where you chugged through the mid range and then hung on for dear life when it hit the power­band. The RZ pulls cleanly from around 4,000 rpm and just keeps on go­ing. It has fan­tas­tic brakes, and with only 145kg to stop, they haul the bike down in no time flat. It’s great fun, par­tic­u­larly on these nearly de­serted coun­try roads, to play with the gear­box and keep the en­gine in its sweet spot at around 6,000 rpm. The first de­cent cor­ner I en­coun­tered was a dis­ap­point­ment, be­cause I im­me­di­ately re­alised I could have taken it at twice the speed with no dra­mas what­so­ever. I re­mem­ber watch­ing the top ex­po­nents of the 250 Pro­duc­tion class of the day as they rock­eted through cor­ners as if on rails, nose to tail, side by side, or both. This is a bike that cries out to be rid­den hard, and it has heaps of ground clear­ance so the tyres (and your own brav­ery) are the lim­it­ing fac­tor, yet it doesn’t com­plain if you just want to cruise along. Steve had ar­rived with his wife Wilma on the pil­lion, and both said the bike just buzzes along hap­pily, with the sweet 6-speed gear­box do­ing its job per­fectly. The seat is in­cred­i­bly plush and com­fort­able, par­tic­u­larly for a bike with a sporty na­ture, and although the footrests and foot con­trols are rear set, the rid­ing po­si­tion does not place too much weight on your wrists – it’s just right. It takes you back when you con­sider this bike is 32 years old, and it also makes you won­der what the RZ350 would have achieved with fur­ther de­vel­op­ment. Af­ter all, Grand Prix 250s were nudg­ing 100 horse­power in the early ‘nineties, so a 350, even a road go­ing one, would have to have had around that much power on hand. What a tan­ta­lis­ing prospect.

RZ350 in a Syd­ney deal­er­ship, circa 1984.

ABOVE The face of the field. RD250LCs line up for prac­tice at Bathurst in 1981. LEFT Af­ter mar­ket pipes have TZ-style alu­minium si­lencers. BE­LOW LEFT Front brakes are bril­liant.

Af­ter mar­ket pipes re­place the stan­dard US jobs that were orig­i­nally fit­ted with in­ter­nal cat­alytic con­vert­ers.

Very neat dash­board. The catal­yser light comes on if the units in­side the pipes over­heat.

Owner Steve Ashke­nazi hav­ing fun.

Neat nose cone sets off the front end nicely. Ra­di­a­tor is alu­minium to save weight.

Rear brake lever is tucked out of the way. ABOVE Front forks have air as­sis­tance for spring­ing, but the tubes are un­for­tu­nately not linked, mak­ing for a fid­dly op­er­a­tion to get them equal. LEFT 26mm carbs on the US mod­els have a crank sys­tem for the ca­bles. The YPVS power valve; ca­ble op­er­ated via in­put from the CDI unit.

Steve Ashke­nazi had an orig­i­nal rear rack hang­ing up in his garage. He must have known he would need it one day. Seat is mighty com­fort­able, even two-up.

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