Honda VF750 Birth of the V4

By the late ‘seven­ties, Honda’s ven­er­a­ble across-the-frame four was look­ing a bit tired, at least in mar­ket­ing terms. In­side the world’s big­gest pro­ducer of mo­tor­cy­cles, it was time for a change. A V change.

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Leav­ing the Grand Prix two-strokes aside, Honda had ini­tially em­barked on a four-cylin­der Vee for­ma­tion four-stroke with the NR500 racer, first seen in 1980. Ex­cept that the NR500, while tech­ni­cally a V4 to com­ply with the FIM reg­u­la­tions that stip­u­lated no more than four cylin­ders in the 500cc class, was re­ally a V8, with eight con­rods, 32 valves and oval pis­tons. His­tory records that the NR500 was a hu­mungously ex­pen­sive ex­er­cise that net­ted just two race wins over two sea­sons – the first at Suzuka in Ja­pan in early 1981 and the sec­ond, and fi­nal, at La­guna Seca, USA in July of the same year, when 19year-old Fred­die Spencer won a five lap sprint race. How­ever, with­out the lessons learned in the NR500 project, painful as they may have been, the fu­ture would have been very dif­fer­ent in­deed. In 1983, Honda sur­ren­dered in the 500 GP class and went with the flow, first with the lithe and user-friendly NS500 v-3 two stroke, and later with the NSR500 V-4 two stroke. But the V-4 four stroke con­cept was not dead, with a line of very suc­cess­ful V-4 en­durance RVF rac­ers emerg­ing. The oval-pis­ton con­cept, for which Honda had filed nu­mer­ous patents, was even dusted off in the form of the 165hp NR750, which was given a win by Tas­ma­nian Mal­colm Camp­bell at the Calder Park round of the 1987 Swann In­sur­ance In­ter­na­tional Se­ries dur­ing the Euro­pean off-sea­son. The FIM replied to that loom­ing threat by ban­ning oval pis­tons from in­ter­na­tional rac­ing. ‘Rac­ing’ here is the key word, be­cause af­ter an­other hia­tus, the oval-pis­ton con­cept ap­peared again in the form of the lus­cious NR750 road bike (also known as the RC40) which made its pub­lic de­but (as a mar­shals’ bike) at the 1990 Suzuka Eight Hour Race. So to hark back to road mo­tor­cy­cles, as op­posed to rac­ing ex­ot­ica, we need to visit 1982, when Honda launched the first road-go­ing V4s, sold as the V45 Sabre in the USA (the ‘45’ re­fer­ring to the ca­pac­ity in cu­bic inches, ac­tu­ally 45.69 ci or 748.8cc) and as the VF750S else­where. For the 1983 Amer­i­can mar­ket, there were also two Magna models – in semi chop­per style – in 45ci and 65ci (1098cc) sizes. These shaft­drive models used a six-speed gear­box. Why a V4 any­way? Back in the ‘thir­ties, both Match­less and AJS had used the lay­out, which is nar­rower than a trans­verse or in-line four, has a ‚

shorter and hence stiffer crank­shaft, and in 90de­gree form, a near per­fect pri­mary bal­ance. As far back as 1919, Mel­bur­nian Sav­ille Whit­ing de­signed and built a com­plete mo­tor­cy­cle pow­ered by his own 500cc side-valve V4 en­gine (see full story in OBA 10). The new Honda en­gines adopted a spec­i­fi­ca­tion of wa­ter-cooled, ninety-de­grees, dou­ble over­head camshafts with four valves per cylin­der, but with ma­jor dif­fer­ences in the cylin­der head de­sign it­self. In place of its tra­di­tional 60-de­gree an­gle be­tween in­let and ex­haust valves, the new V4 used a 38 de­gree an­gle, ba­si­cally taken from the NR500, with a flat­ter com­bus­tion cham­ber and pis­ton crown. In USA, the Sabre and Magna models sold in sat­is­fac­tory num­bers, the larger V65 par­tic­u­larly, es­pe­cially af­ter Honda hired top drag racer Jay Glea­son who took the ma­chine to a 10.92 sec­ond quar­ter-mile time at Or­ange County Race­way in Cal­i­for­nia – at that stage, the fastest pro­duc­tion mo­tor­cy­cle ever tested. Honda made much of the achieve­ment, and the fact that the V65 was ac­tu­ally built in USA at the Marysville, Ohio plant which had pre­vi­ously built Gold­wings. The Euro­pean mar­ket on the other hand was luke­warm to the V4 con­cept. Af­ter all, Honda al­ready had an ex­cel­lent de­sign – and a highly suc­cess­ful one in TT rac­ing – in the DOHC CB750 and CB900 models. But in 1983, along came a sub­stan­tially re­designed V4, known as the V45 In­ter­cep­tor in USA and the VF750F in other mar­kets, in­clud­ing Aus­trala­sia. The VF750F used ba­si­cally the same en­gine, but with a five-speed gear­box. This change came about be­cause of the choice of chain drive over the ear­lier shaft, mean­ing a smaller gear­box ca­pac­ity and room for only five ra­tios to fit com­fort­ably. It used a rect­an­gu­lar-sec­tion steel frame which was di­men­sion­ally sim­i­lar to the rac­ing RS1000RW that had en­joyed much suc­cess in AMA, En­durance, and even TT rac­ing. The frame was painted sil­ver and neatly matched the alu­minium-al­loy swing­ing arm. Honda also man­aged to re­duce the price in most mar­kets to some­where near that of the CB models, and with 86bhp and around 210km/h avail­able straight out of the box, the V4 was un­de­ni­ably quick. The styling was all- new, with a pur­pose­ful three-way ad­justable airas­sisted front end fea­tur­ing Honda’s TRAC anti-dive, with a half fair­ing to con­tain in­stru­ments and warn­ing lights, as well as pro­vide a de­gree of wind-cheat­ing. Honda chose a 16-inch front wheel, which was at the time the way to go in GP rac­ing but was soon su­per­seded by the 16.5 and later 17 inch hoops, with an 18-inch at the rear, sus­pended by the com­pany’s ProLink sys­tem with four-way damp­ing ad­just­ment. Front forks were an in­ter­est­ing de­sign with air as­sis­tance and, on the right side leg only, three-way damp­ing ad­just­ment. To keep ev­ery­thing cool, the liq­uid passed through twin ra­di­a­tors, and although this should have been en­tirely ad­e­quate, very soon af­ter its re­lease re­ports be­gan fil­ter­ing in of over­heat­ing is­sues, and worse still, pre­mature camshaft wear. Honda had a big in­vest­ment in the long-term vi­a­bil­ity of this con­cept, so sprang into ac­tion to mount a rem­edy be­fore it be­came a pan­demic. What tran­spired tar­nished the model’s rep­u­ta­tion con­sid­er­ably – not to men­tion its sales – and for a an ex­pla­na­tion we turn to the words of au­thor and model ex­pert Greg Pullen in his 2014 book, Honda V4. The Com­plete Four Stroke Story. “Although the the­o­ries and fixes came thick and fast, start­ing with re­vised jet­ting and then var­i­ous camshafts and tools for tap­pet ad­just­ment, the re­li­a­bil­ity and qual­ity-con­trol prob­lems of the 1982 VF model were even­tu­ally at­trib­uted to the au­to­mated pro­duc­tion equip­ment…Re­vi­sions were brought in in 1983 to ad­dress the prob­lems from the pre­vi­ous pro­duc­tion year…but they proved in­ad­e­quate. More camshaft woes sur­faced dur­ing 1984, with half a dozen cam re­vi­sions over the course of a sin­gle year. With the early V4s, the prob­lem with camshaft wear – in an ironic twist – was blamed on the de­ci­sion to use ‘less trou­ble­some’ threaded tap­pet ad­just­ment rather than shims...In essence, the prob­lem was that the camshafts could rock in their bear­ings if the tap­pet ad­just­ment was in­cor­rect, or if the top and bot­tom cast­ings that had the camshaft bear­ings ma­chined into them were not a good match. Honda did not match com­po­nents to get the best fit from the in­evitable vari­a­tions in mass pro­duc­tion, in­stead trust­ing to the pre­ci­sion of their new ma­chin­ery to avoid such vari­a­tions. In ad­di­tion, rough cast­ings could lead a me­chanic to ‘feel’ he had the tap­pet cor­rectly ad­justed and se­cured by a lock­nut, when in fact fur­ther tight­en­ing was needed.

“As a re­sult, camshafts and cylin­der heads con­tin­ued to wear cat­a­stroph­i­cally…At first, Honda be­lieved the so­lu­tion lay in im­proved oil­ways, and they pressed ahead with V4 road bikes in an ever higher state of tune, with dis­as­trous re­sults. These prob­lems were most ob­vi­ous and em­bar­rass­ing on the VF750F (In­ter­cep­tor). Per­haps this was in­evitable given that this was the V4 in the high­est state of tune (90hp at 10,000 rpm was phe­nom­e­nal for a four-stroke 750 road­ster in 1983), and be­cause the model was most likely to be bought by a de­mand­ing rider. Be­cause the V4’s woes stemmed from un­matched com­po­nents, some en­gines were af­fected more than oth­ers, and some not at all; it all de­pended on how poorly the com­po­nents matched one an­other when they came to­gether on the pro­duc­tion line.”

A Colo­nial cri­sis

In Aus­tralia, and in New Zealand, the Cas­trol Six Hour Race was the ul­ti­mate show­room shootout; strictly su­per­vised stock-stan­dard models go­ing head-to-head in a con­test of speed, re­li­a­bil­ity, and in­creas­ingly, tyres. Based at Syd­ney’s Ama­roo Park since 1970, Honda had won the race only three times; with Bryan Hin­dle and Clive Knight in 1972 on a CB750, in 1980 when Wayne Gard­ner and An­drew John­son tri­umphed on the race-replica CB1100RB, and in 1982 with Gard­ner and Wayne Clarke on a CB1100RC. The or­gan­is­ers, Wil­loughby District MCC, were get­ting peeved over the hi­jack­ing of their race ‘for stan­dard tour­ing mo­tor­cy­cles’ by the new breed of thinly-dis­guised rac­ing ma­chines, and for 1983 in­tro­duced new reg­u­la­tions that re­duced the top limit to 1000cc and ren­dered the 1100 Hon­das and Suzuki Katanas ob­so­lete. Suzuki re­sponded with a 1000cc ver­sion of the Katana for the Out­right (751cc to 1000cc) class, but the ma­jor­ity of the en­tries for the Oc­to­ber 1983 race were for the Up to 750cc class, and over­whelm­ingly by Honda VF750 run­ners, 14 in fact. Many felt the 750s were the choice for Out­right hon­ours, and qual­i­fy­ing showed this, with VF750s tak­ing the first three spots on the grid and seven of the first eight. Mal­colm Camp­bell’s pole po­si­tion lap of 55.72 sec­onds was a full two sec­onds faster than a 750 had ever man­aged be­fore, and marginally faster than the 1100s had done in the 1982 race. Just 0.21 sec­onds cov­ered the first five qual­i­fiers!

There was how­ever, the bug­bear of re­li­a­bil­ity, given the VF750s’ ap­petite for top end com­po­nents. In prac­tice, Bernie Sum­mers’ VF750 broke a con­rod and dumped him heav­ily. Prior to the start, the Camp­bell/Cox Honda was fit­ted with a 140/80-18 rear tyre, a slightly higher pro­file than the stan­dard 140/70. This gave a frac­tion more ground clear­ance and higher over­all gear­ing, keep­ing the revs down and al­low­ing what proved to be vi­tal ex­tra min­utes be­tween fuel stops. In the race, Camp­bell and corider Rod Cox hardly put a foot wrong in a nail-bit­ing con­test that saw the first four placeget­ters (three of them VF750s) fin­ish on 372 laps – five laps more than were achieved in 1982. As it tran­spired, the lap and race records would stand for all time, for this was the fi­nal Six Hour at Ama­roo be­fore the race moved to Oran Park for 1984. The re­sult also proved at least one thing; that when the en­gine com­po­nents were prop­erly matched and metic­u­lously as­sem­bled (as they should have been from the fac­tory), the VF750 was re­li­able as well as sen­sa­tion­ally fast.

A one-owner ex­am­ple

Ken Wil­son has owned the fea­tured VF750FD since new in June 1983. To say that Ken has been a life­long keen mo­tor­cy­clist would be an un­der­state­ment. Dur­ing the ‘six­ties his mode of trans­port was a 500cc Ve­lo­cette Venom and it did daily du­ties as his ride-towork ma­chine, and on week­ends would fre­quently un­der­take lengthy trips. When Oran Park opened in west­ern Syd­ney, Ken was a reg­u­lar spec­ta­tor, rid­ing the Velo from his home in Mel­bourne. The re­turn trip would in­volve leav­ing the cir­cuit by mid af­ter­noon and rid­ing all night (of­ten in rain) to reach work by open­ing time on Mon­day morn­ing. No mo­tor­ways

in those days, just the old, rough, sin­gle lane Hume High­way. As cir­cum­stances per­mit­ted, the Velo gave way to a se­ries of other bikes, and fi­nally the VF750. This was pur­chased from Ken’s em­ployer, Free­dom Wheels Honda at Ring­wood, Vic­to­ria, owned by Frank Hod­der and where lead­ing racer Alan Decker was man­ager, with Ken in charge of spare parts. As pre­vi­ously noted, there were good and not-so­good ex­am­ples of this model to leave the Honda fac­tory, and Ken’s un­for­tu­nately fell into the lat­ter cat­e­gory. Over­heat­ing was a prob­lem that reared its head early in the piece, to the point that Ken fit­ted an aux­il­iary switch to over-ride the au­to­matic cut-in for the ra­di­a­tor fans. In traf­fic or on hot days, he would sim­ply switch on the fans be­fore things got to hot to han­dle. Still, that was a Band Aid so­lu­tion for a much more se­ri­ous prob­lem, in­volv­ing a se­ries of war­ranty re­pairs. The first fault to be cor­rected was the fac­tory-re­place­ment large ca­pac­ity oil line feed­ing the vi­tal fluid to the cylin­der head, but by the time 10,ooo km had been clocked up, the in­ter­nal com­po­nents were in bad or­der, as Ken ex­plains. “There was vir­tu­ally no hard­en­ing on the cams, nor on the fol­low­ers, they just turned blue and wore out. Honda re­placed these items, as well as the pri­mary gears, which came from the new VF1000 model re­leased in 1984. The clip-on han­dle­bars were also re­placed as these were prone to break­ing, as An­drew John­son, who rode for Free­dom wheels, dis­cov­ered. I had been run­ning on 98 oc­tane fuel but it caused all sorts of prob­lems. Mick Smith, race me­chanic for Jef­frey Sayle and oth­ers, told me that the en­gine would not get hot enough to burn off the ad­di­tives in the high oc­tane fuel, so I should use 91 and see if the mo­tor pinged. It did, so I went to BP 95 and it was OK from then.” “I had to re­place the rear hub cush-drive and at about 40,000km the rear shock went. I man­aged to find a gen­uine re­place­ment in Queens­land but that only lasted 18 months be­fore it went too, so I got in touch with Dar­ryl Groat and he sup­plied a Hagon shock which is still in the bike. The orig­i­nal black muf­flers rusted out too, along with the col­lec­tor box, de­spite the fact that I did no short trips and al­ways warmed the bike up prop­erly to get rid of con­den­sa­tion. Stu­art Strick­land from Honda man­aged to find one orig­i­nal black pipe but not the other so I went to Mark Har­ris who made Madaz stain­less steel pipes at his fac­tory. No more prob­lems and no col­lec­tor box ei­ther. But the big is­sue was when I got a crook batch of fuel which ba­si­cally wrecked the en­gine. It cost $3,000 to re­build and I didn’t have that so I got John Buskis at A1 Mo­tor­cy­cles to do the work and I paid it off in in­stal­ments. Af­ter that, the bike ran per­fectly right un­til I took it off the road five years ago due to per­sonal health is­sues.” De­clin­ing health has re­cently forced Ken to part with the Honda, and I was for­tu­nate to be able to take it for a spin, never hav­ing rid­den one be­fore. Although it had been laid up for a num­ber of years, once a new bat­tery was fit­ted and with a fresh tank of fuel, it fired up in­stantly and set­tled into a steady tick-over. Although the tyres had some age on them, they were oth­er­wise in very good con­di­tion. Although it is now 35 years old, ev­ery­thing on this mo­tor­cy­cle works per­fectly; tes­ta­ment to Ken’s metic­u­lous main­te­nance.

In the sad­dle

There are a lot of nice de­tails about the VF750, even the fuel tap which is not the usual fid­dly lever but a very pur­pose­ful look­ing unit set into the left side of the fuel tank. The red-faced in­stru­ments are all there in the panel set into the fair­ing – fuel ca­pac­ity, speedo, tacho, and most im­por­tant of all – en­gine tem­per­a­ture. There’s also a whole row of those coloured lights so beloved by all the Ja­panese man­u­fac­tur­ers of the time, show­ing turn sig­nals, high beam, and warn­ing lights for oil pres­sure and tail light op­er­a­tion. The mir­rors are set high, so you can ac­tu­ally use them. Ken’s bike still has the re­mov­able seat cowl that con­verts it from (or to) a dual seater, as it had to be for the Cas­trol Six Hour Race, and this is a part that is in scarce sup­ply and prized by col­lec­tors.

For a sports ma­chine, the VF750 is a fairly unique propo­si­tion in terms of rid­ing po­si­tion. The seat is very com­fort­able, the footrests slightly set to the rear, and the han­dle­bars at a height that doesn’t tax your wrists too greatly, although it is cer­tainly a for­ward lean­ing at­ti­tude. The quicker you ride this bike, the bet­ter it feels, be­cause at around-town speeds it comes across as a bit way­ward in the front end, a trait I am sure that has a lot to do with the fat 16 inch front tyre. Turn up the wick though, and off it goes, mak­ing a glo­ri­ous rasp­ing ex­haust note on the way. Ken told me that he thought the gear­box was a bit dodgy chang­ing back down, but I ex­pe­ri­enced none of this, in fact I couldn’t fault the op­er­a­tion of the gear­box in ei­ther di­rec­tion, other than you seem to grab top gear a lot ear­lier than you may think. Part of this is be­cause although the en­gine loves to rev, it also pulls like a train from 2,500 in top gear, with bags of mid-range torque, and no flat spots. It’s a gem. I found the front brakes a bit spongy, but they cer­tainly did their job, and I think a sim­ple fluid change and bleed would re­store them to full health. Re­mem­ber too, that the VF750, while a sporty steed, is no feath­er­weight, so there is a bit of beef to haul down. I had no op­por­tu­nity to fid­dle with the air-ad­justable front forks, and I reckon the pe­riod spent laid up in the garage has also dulled the edge here, but that’s an easy fix. The rear end, on the other hand, felt ex­cel­lent.

As I said, where the VF750 hits its straps is through quick cor­ners and on the gas. The chas­sis is rock steady even with the old tyres, and the bike can be flicked from side to side with­out even think­ing about it. I can see now why it was such a weapon around Ama­roo Park, and co­in­ci­den­tally I passed the for­mer en­trance gates to that cir­cuit on my test ride. Sadly, the track is long gone – the scene of per­haps the VF750’s finest hour, or six.

TOP Heart of the mat­ter. Note hy­draulic clutch. ABOVE CEN­TRE Snazzy look­ing cock­pit with mir­rors that ac­tu­ally work. ABOVE Twin ra­di­a­tors, up­per and lower. ABOVE RIGHT Ken fit­ted air horns in place of the orig­i­nals. RIGHT Re­mov­able seat cowl that con­verts it from (or to) a dual seater, a part that is in scarce sup­ply and prized by col­lec­tors.

LEFT Honda’s TRAC anti-dive front end, with 16 inch front wheel. ABOVE Flush-fit­ting air­craft-style fuel tap. RIGHT Mel­bourne-made Madaz muf­flers look and sound su­perb.

Rod Cox shared the win­ning VF750 with Mal­colm Camp­bell. Rob Phillis and co-rider Ge­off French lost 75 sec­onds when the en­gine re­fused to start fol­low­ing a pit stop, and lost the race by 26 sec­onds.

RIGHT The VF750 out­side the scene of its great­est tri­umph. BE­LOW Graeme Crosby made a brief rac­ing come­back on the Ap­ple Com­put­ers VF750, but crashed late in the race.

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