Honda RC166

{{Short description|6 cylinder racing motorcycle}} {{Use dmy dates|date=May 2026}} {{Use British English|date=May 2026}} {{Infobox motorcycle | name = Honda RC166 | image = Honda RC166.jpg | alt = | caption = 1967 RC166 that was ridden by [[Mike Hailwood]] on display at the [[Honda Collection Hall|Honda Museum at Motegi]]. | aka = | manufacturer = [[Honda Racing Service Club]] | parent_company = [[Honda]] | production = 1966-1967 | assembly = [[Asaka, Saitama]], Japan | predecessor = [[Honda RC164]] | successor = | class = | engine = [[Air cooled]] [[inline 6]] [[4 stroke]] | bore_stroke = {{convert|41|x|31|mm|abbr=on}} | compression = 11.0:1 | top_speed = | power = {{convert|60|bhp|abbr=on}} @ 18,000 rpm | torque = | ignition = | fuel_delivery = | transmission = 7 speed [[gearbox]], [[chain drive]] | frame = [[Motorcycle frame#Full duplex cradle|Duplex cradle]] | suspension = Front: [[telescopic fork]]s Rear: [[swinging arm]] | brakes = [[Drum brake]]s front and rear | tires = | rake_trail = | wheelbase = {{convert|55.5|in|abbr=on|order=flip}} | length = | width = | height = | seat_height = | dry_weight = {{convert|112|kg|abbr=on}} | wet_weight = | fuel_capacity = | oil_capacity = | fuel_consumption = | turning_radius = | range = | ground_clearance = | related = | sp = UK | footnotes = <ref>{{cite web |title=Honda RC166: A Legendary Racing Motorcycle |url=https://pyramidmoto.co.uk/blogs/news/honda-rc166-a-legendary-racing-motorcycle?srsltid=AfmBOopFQH1lG8qBbjoNuzbWP1cS9LozZScEmXbYoO0J8i-c9_frwtQD |website=Pyramid Motorcycle Accessories |date=27 February 2023 |access-date=8 May 2026 |language=en}}</ref><ref name="vf750fd 66">{{cite web |last1=Kortekaas |first1=Joep |title=Honda's Race History - 1966 |url=https://www.vf750fd.com/Joep_Kortekaas/1966.html |website=www.vf750fd.com}}</ref><ref name="Motorcyclist" /> }} The '''Honda RC166''', also known as the ''Honda 6'', is a [[Grand Prix motorcycle racing|Grand Prix]] racing motorcycle produced by [[Honda]] which raced in 1966 and 1967. The technological advanced bike was a {{convert|250|cc|abbr=on}} [[DOHC]] [[air-cooled]] [[inline 6]]. On the bike [[Mike Hailwood]] took the 250cc riders championship and Honda the constructors championship in both years it raced. It was evolved from the earlier 3RC164 and RC165.

==Background== Honda had first enterered GP racing in 1959 and by 1962 were dominating the 250 cc class. In 1964 the Hondas were no match for the [[Yamaha RD56]].<ref name="seminuevos">{{cite web |title=Honda RC166: reviviendo una vieja gloria de seis cilindros y un cuarto de litro |url=https://www.seminuevos.com/blog/honda-rc166-reviviendo-historia/ |website=Blog de Seminuevos.com |access-date=8 May 2026 |language=es |date=18 March 2015 |trans-title=Honda RC166: Reviving an old glory of a quarter-liter six-cylinder}}</ref> The existing [[inline 4]] [[Honda RC164|RC164]] was at the limit of it's development.<ref name="Cycle World">{{cite web |last1=Cameron |first1=Kevin |title=Calming The Crankshaft Of Honda's Six-Cylinder Racer |url=https://www.cycleworld.com/calming-crankshaft-hondas-six-cylinder-racer/ |website=[[Cycle World]] |access-date=10 May 2026 |language=en |date=19 December 2017}}</ref> Honda started working on a new model to restore their dominance in the class.<ref name="voromv">{{cite web |title=Musica celestial. Honda RC166 250/350cc 4t, 6 cilindros. |url=https://www.voromv.com/2023/08/musica-celestial-honda-rc166-250cc-4t-6.html |access-date=8 May 2026 |language=es |trans-title=Heavenly music. Honda RC166 250/350cc 4-stroke, 6-cylinder}}</ref> The engineer put in charge of the project was 24 year old [[Shoichiro Irimajiri]].<ref name="Motorcyclist">{{cite web |last1=Frank |first1=Aaron |title=Honda RC166 250/6 |url=https://www.motorcyclistonline.com/honda-rc166-250-6/ |website=Motorcyclist |access-date=8 May 2026 |language=en |date=4 May 2012}}</ref>{{efn|Irimajiri also designed the twin cylinder 50 cc [[Honda RC115|RC115]], five cylinder [[Honda RC148|RC148]] and worked on the [[Honda RA270|RA270]] [[Formula 1]] engine.<ref name="Motor Sport Magazine">{{cite web |last1=Oxley |first1=Mat |title=Honda's 1960s Japanese screamers — the motorcycles that changed grand prix racing |url=https://www.motorsportmagazine.com/archive/article/november-2019/104/honda-1960s-motorcycles/?srsltid=AfmBOooLiFoesDUAr-QRPkGbsKgickMA-TUFd3YNIRZ3uBJDeJT6zDcb |website=Motor Sport Magazine |access-date=9 May 2026 |date=17 November 2023}}</ref> Irimajiri later led the design teams for the [[Honda Gold Wing|Gold Wing]]<ref>{{cite web |title=Hondas in Japan/From Torture To The Turbo |url=https://www.advrider.com/from-torture-to-the-turbo/ |website=Adventure Rider |access-date=12 May 2026 |date=25 September 2023}}</ref> and [[Honda CBX|CBX]].<ref>{{cite web |title=Honda CBX1000 {{!}} A retrospective |url=https://www.mcnews.com.au/honda-cbx1000/ |website=MCNews |access-date=12 May 2026 |date=10 December 2004}}</ref>}} Design started in January 1964<ref name="Martin">{{cite book |last1=Martin |first1=Guy |author-link=Guy Martin |title=We Need to Weaken the Mixture |date=18 October 2018 |publisher=Random House |isbn=978-0-7535-4548-5 |url=https://books.google.com/books?id=BJ9HDwAAQBAJ |language=en}}</ref> and the initial sketches were completed in February 1964.<ref name="Motorcyclist" /> A running engine was produced in June.<ref name="Martin" />

==Predecessors== ===3RC164=== [[2 stroke]] engines, as used by competitors [[Suzuki]] and [[Yamaha Motor Company|Yamaha]], have a power stroke every [[crankshaft]] rotation, whereas [[4 stroke]]s as used by Honda only produce a power stroke every 2 rotations of the crankshaft. [[Soichiro Honda]] had already made a public commitment to make quieter, cleaner running, more efficient 4 strokes. The solution was to make the four stroke rev higher to produce more power strokes. To achieve this while maintaining reliability Irimajiri reduced reciprocating weight by using 6 cylinders and [[Multi-valve#Four valves|4 valve]] [[Cylinder head|heads]]. The engine was an engineering masterpiece, no wider then the four it replaced and narrower than the Yamaha twin.<ref name="Motorcyclist" />

Although being developed for the 1965 season, the bike was ready<ref name="vf750fd 64">{{cite web |last1=Kortekaas |first1=Joep |title=Honda's Race History - 1964 |url=https://www.vf750fd.com/Joep_Kortekaas/1964.html |website=www.vf750fd.com |access-date=12 May 2026}}</ref> for the September 1964 [[Italian motorcycle Grand Prix|Nations Grand Prix]] at [[Monza Circuit|Monza]]. It was designated 3RC164, to suggest to competitors that it was an evolution of the existing four cylinder machine. The bike was shipped with only four exhausts to further fool the competition.<ref name="Motorcyclist" /> The bike was sent to Monza in secrecy. Some sources give it accompanying engineer Michihiko Aika and rider [[Jim Redman]] on a [[BOAC]] [[VC10]] from [[Tokyo]] to Monza. The 3RC164 proved to be faster than the Yamahas but suffered a vapour lock in the carburettors.<ref name="Motor Sport Magazine" /> [[Phil Read]] won the race on a RD56 clinching the championship, Yamaha's first World Championship.<ref>{{cite web |last1=Dawes |first1=Geoff |title=Grand Prix motorcycle racing |url=https://motovue.net/tag/grand-prix-motorcycle-racing/ |website=MotoVue |access-date=9 May 2026 |language=en |date=15 September 2014}}</ref> At the following GP, the [[Japanese motorcycle Grand Prix|Japanese GP]] at Honda's circuit [[Suzuka Circuit|Suzuka]], Redman won on the 6.<ref name="Motorcyclist" />

===RC165=== Early in the 1965 season an updated version, the RC165, was introduced. Honda did not attend the 1965 season opener at [[Daytona International Speedway|Daytona]] and in the 2nd round at the [[Nürburgring]] Redman fell and injured himself in the 350cc race. This prevented him starting the 250 race and also caused him to miss the 3rd round in [[Montjuïc Circuit|Spain]]. Fit again for [[Rouen-Les-Essarts|France]], he suffered gearbox problems whilst in the lead. In [[Dundrod Circuit|Ulster]] Redman fell in the 350 race and broke his collarbone. This putting him out the 250 race and the following round. Feeling fit enough to race at Monza he was told his bike had not been sent to the circuit so he stayed at home in Rhodesia.<ref name="vf750fd 65">{{cite web |first=Joel |last=Kortekaas |title=Honda's Race History - 1965 |url=https://www.vf750fd.com/Joep_Kortekaas/1965.html |website=www.vf750fd.com |access-date=12 May 2026}}</ref>{{efn|This was due to miscommunication within Honda and the bike actually had been sent to Monza<ref name="vf750fd 65" />}} Although only competing in 6 rounds of the championship Redman achieved 3 wins, a second and a third, finishing 3rd in the championship.<ref name="MotoGP">{{cite web |title=MotoGP™ Riders {{!}} Jim Redman |url=https://www.motogp.com/en/riders/jim-redman/7435f9e4-13f7-4053-be64-975735860cc4?tab=overview |website=The Official Home of MotoGP |access-date=9 May 2026 |language=en}}</ref> Honda finished 2nd in the constructors championship.<ref name="vf750fd 65" />

Late in 1965 Mike Hailwood signed a contract to returned to Honda for £40,000. Honda convinced the organisers of the season finale, the [[Japanese motorcycle Grand Prix|Japanese Grand Prix]], to move the 250 race to the end of the programme so Hailwood could fulfil his [[MV Agusta]] contract racing their 350 and then ride the Honda in the 250 race. After winning the race on the RC165 his opinion of it was ''bloody awful''.<ref name="SPEEDWEEK">{{cite web |title=56 Jahre vor Kalex: Die Honda von Mike Hailwood |url=https://www.speedweek.com/a/motogp/56-jahre-vor-kalex-die-honda-von-mike-hailwood |website=SPEEDWEEK.com |access-date=10 May 2026 |language=de |date=20 May 2023 |trans-title=56 years before Kalex: Mike Hailwood's Honda}}</ref> Hailwood allegedly asked the mechanics to remove the rear suspension units and then threw them in a pond telling the mechanics to fit [[Lucas Industries#Girling|Girling]] units. He also asked for a new frame made of stiffer tubing and with the [[wheelbase]] lengthened {{convert|3.5|in|abbr=on}},<ref name="Motorcyclist" /> and suggested Dutchman Nico Bakker built the new frame but Honda baulked at an outsider being involved.<ref>{{cite web |last1=Bloemendaal |first1=Willem |title=Honda 6 cylinder, Mike Hailwood, wereldkampioen 1971 |url=https://www.modelmotoren.nl/motoren-overige-race-klasse/honda-6-cylinder |website=www.modelmotoren.nl |language=nl |trans-title=Honda 6-cylinder, Mike Hailwood, 1971 World Champion}}</ref> Redman had also been urging Honda all season to develop the bike further.<ref name="SPEEDWEEK" />

==RC166== For 1966 an updated version, the RC166 was introduced.<ref name="SPEEDWEEK" /> With the stiffer and longer frame Hailwood had requested the handling of the bike improved significantly.<ref name="Motorcyclist 2">{{cite web |last1=Frank |first1=Aaron |title=Mike Hailwood and His Bike: Honda RC166 {{!}} ICON |url=https://www.motorcyclistonline.com/blogs/mike-hailwood-and-his-bike-honda-rc166-icon/ |website=Motorcyclist |access-date=10 May 2026 |language=en |date=20 May 2011}}</ref> Hailwood and the RC166 were dominant in 1966, winning all 10 of the races he entered,<ref name="Motorcyclist" /> although only the best 7 results counted towards the championship.<ref name="Cycle World" /> As well as Hailwood's rider's championship Honda won the constructors title.<ref name="MaxxMoto">{{cite web |last1=Jaspers |first1=Arno |title=Eregalerij: Honda RC166 |url=https://www.maxxmoto.be/reportages/eregalerij-honda-rc166/ |website=MaxxMoto |access-date=10 May 2026 |language=nl-BE |date=27 March 2025 |trans-title=Hall of Fame: Honda RC166}}</ref>

Redman crashed in the 500 race at [[Circuit de Spa-Francorchamps|Spa]] in torrential rain breaking his wrist. When his wrist was too painful to race at Ulster five weeks later he decided to retire.<ref name="MotoGP" /> [[Stuart Graham (motorcyclist)|Stuart Graham]], son of [[Leslie Graham]], is brought in to replace Redman.<ref name="vf750fd 66" />

[[Ralph Bryans]] partnered Hailwood on the RC166s for 1967.<ref name="vf750fd 67">{{cite web |last1=Kortekaas |first1=Joep |title=Honda's Race History - 1967 and 1968 |url=https://www.vf750fd.com/Joep_Kortekaas/1967.html |website=www.vf750fd.com |access-date=12 May 2026}}</ref> Yamaha had developed a [[water cooled]] [[Yamaha 250 V4|250 V4]] in response to Honda's 6. For 1967 it was re-engineered to reduce size and weight.<ref>{{cite web |title=RD05A - Racing Information {{!}} Yamaha Motor Co., Ltd. |url=https://global.yamaha-motor.com/race/wgp-50th/race_archive/machines/rd05a/ |website=global.yamaha-motor.com |access-date=10 May 2026}}</ref> Hailwood and Yamaha's Read tied for points at the end of the season. Hailwood won the championship as he had five wins as opposed to Read's four. Honda won the constructors title for the second year running.<ref name="vf750fd 67" />

At the end of 1967 the [[Fédération Internationale de Motocyclisme|FIM]] introduced new regulations for the 1968 season that levelled the playing field and favoured the European manufacturers, leading to Honda withdrawing from GP racing.<ref>{{cite web |last1=Diaz-Valdés |first1=Tomás |title=Una moto de leyenda: Honda RC 166 |url=https://www.motorpoint.com/una-moto-de-leyenda:-honda-rc-166 |website=motorpoint.com |access-date=8 May 2026 |language=es |date=17 February 2017 |trans-title=A legendary motorcycle: Honda RC 166}}</ref> Paddock rumours were that the 6 would have been replaced with a new water cooled [[V8]] in 1968 if Honda hadn't have withdrawn from GP racing.<ref name="Cycle World" /> Honda presented Hailwood with a RC166 in recognition of his two world titles on the model.{{efn|The bike was displayed in the [[Birmingham]] motorcycle showroom that Hailwood owned with [[Rodney Gould (motorcyclist)|Rod Gould]]. After Hailwood's death Gould sold the bike to a Dutch collector. Hailwood’s widow, Pauline, put the matter in the hands of the police when she realised the bike was missing. Although Gould was convicted of theft the bike was never returned.<ref name="Cycle World 2" />}}<ref name="Cycle World 2">{{cite web |last1=Duckworth |first1=Mick |title=Hailwood's Honda In Holland |url=https://magazine.cycleworld.com/article/1992/9/1/hailwoods-honda-in-holland |website=Cycle World {{!}} The Complete Archive |access-date=10 May 2026 |date=September 1992}}</ref> They also lent [[Ralph Bryans]], who had won the 50cc title for Honda in 1965, three bikes for 1968 including a RC166 to compete in non-championship events. Bryans had to maintain the bikes himself.<ref name="Motor Sport Magazine" />

==350cc RC174== {{main|Honda RC174}}

In 1966 Hailwood had complained about the handling of the 350cc four cylinder [[Honda RC173|RC173]]. For 1967 Honda produced a larger capacity version of the RC166 to race in the 350 category. The stroke had been increased to {{convert|37.5|mm|abbr=on}} giving a capacity of {{convert|297|cc|abbr=on}}. Hailwood won the first 5 races of the season which was enough to secure the championship. Bryans rode the bike for the rest of the season and finished 3rd in the championship.<ref name="vf750fd 67" />

==Technical details== ===Engine=== [[File:Honda RC165E engine front Honda Collection Hall.jpg|thumb|Honda RC165 engine]] The compact 6 was no wider than the 4 it replaced. The block was cast as part of the upper crankcase and the heads were cast in two pieces, one for each 3 cylinders.<ref name="Motorcyclist" /> The engine extensively used [[titanium]]<ref>{{cite web |last1=Macauley |first1=Iain |title=Mike Hailwood's Honda RC174 replica is motorcycling perfection reborn |url=https://www.gq-magazine.co.uk/cars/article/mike-hailwoods-honda-rc174-replica-reborn |website=British GQ |access-date=10 May 2026 |date=21 March 2021}}</ref> and [[magnesium]] castings and revved to over 18,000 rpm.<ref name="Motorcyclist 2" />

The [[crankshaft]] was pressed up on precision jigs from 13 separate components.<ref name="Petrolicious">{{cite web |last1=Franklin |first1=Alan |title=Honda's RC166 Had More than Met the Eye |url=https://petrolicious.com/blogs/articles/honda-rc166?srsltid=AfmBOop3KkA46SWQlyz-ITOsePADeHwyWOG693_8-5LVqqQynSl5O1Ux |website=Petrolicious |access-date=10 May 2026 |language=en |date=5 April 2013}}</ref> To reduce the effective vibrating length of the crankshaft, drive to the clutch was transmitted through a [[jack shaft]] driven by a gear between cylinders 3 and 4. Because the torsional forces on the built-up crank were greater near the centre of the engine, different sized [[crankpin]]s were used, largest for cylinders 3 and 4, smaller for 2 and 5 and the smallest on 1 and 6.<ref name="Cycle World" /> [[Conrod]]s were one-piece with roller bearings.<ref name="Motor Sport Magazine" />

Drive for the [[camshaft]]s was by a train of spur gears between cylinders 2 and 3.<ref name="Cycle World" /> The camshafts were barrel shaped with the greater mass at the centre to minimise flexing.<ref name="Petrolicious" /> 4 valve heads were fitted with each one of the four valves a different shape.<ref>{{cite web |last1=Hancocks |first1=Simon |title=This screaming Honda 'Six' around the IoM TT course is awesome!! |url=https://www.visordown.com/news/viral/screaming-honda-%E2%80%98six%E2%80%99-around-iom-tt-course-awesome |website=www.visordown.com |access-date=10 May 2026 |language=en |date=24 June 2019}}</ref>

The RC166 had a bore and stroke of {{convert|41|x|31|mm|abbr=on}} giving {{convert|245.6|cc|abbr=on}}.<ref name="vf750fd 66" /> ({{convert|39|x|34.5|mm|abbr=on}} (247.3cc) on the 3RC164<ref name="vf750fd 64" /> and {{convert|39|x|34.8|mm|abbr=on}} (249.4cc) on the RC165)<ref name="vf750fd 65" />

Transmission was via a multi-plate [[dry clutch]], 7 speed gearbox (8 on the RC165) and [[chain drive]]. It produced {{convert|60|bhp|abbr=on}} at 18,000 rpm. ({{convert|54|bhp|abbr=on}} at 17,000 rpm for the 3RC164, {{convert|56|bhp|abbr=on}} at 16,500 rpm for the RC165)<ref name="vf750fd 66" /><ref name="vf750fd 64" /><ref name="vf750fd 65" />

Two oil coolers were fitted on the RC165, one in each side of the fairing.<ref name="vf750fd 66" />

===Cycle parts=== The bike used a [[Motorcycle frame#Full duplex cradle|duplex cradle]].<ref name="Motorcyclist" /> It was stiffer and had a longer wheelbase than the original frame of the 3RC164 and RC165.<ref name="Motorcyclist 2" /> Front forks were [[Telescopic fork|telescopic]] and the [[swinging arm]] was controlled by 2 Girling [[shock absorber]]s (Honda shocks on the 3RC164 and RC165). The brakes were [[Drum brake|drums]], a {{convert|9|in|abbr=on|order=flip}} 4ls on the front and {{convert|8|in|abbr=on|order=flip}} [[Twin-leading-shoe drum brake|2ls]] on the rear, both brakes were fitted with cooling rings. Wheels were 18 inch shod with [[Dunlop Tyres|Dunlop]] K124 tyres.<ref name="Motorcyclist" />

==Racing results==

Points were awarded to the top six finishers in each race. Only the best six races were counted in 1964 and 1966, 7 in 1965 and 1967

{| class="wikitable" style="font-size:85%; text-align:center" |- ! Position !  1st  !  2nd  !  3rd  !  4th  !  5th  !  6th  |- ! Points |style="background:#ffffbf;"| 8 |style="background:#dfdfdf;"| 6 |style="background:#ffdf9f;"| 4 |style="background:#dfffdf;"| 3 |style="background:#dfffdf;"| 2 |style="background:#dfffdf;"| 1 |}

{| | valign="top"| {| class="wikitable" style="text-align:center; font-size:90%" ! Year ! Rider ! 1 ! 2 ! 3 ! 4 ! 5 ! 6 ! 7 ! 8 ! 9 ! 10 ! 11 ! 12 ! 13 ! Points ! Rank ! Wins |- ! [[1964 Grand Prix motorcycle racing season|1964]] ! {{flagicon|Rhodesia and Nyasaland}} [[Jim Redman]] | [[United States motorcycle Grand Prix|USA]] | [[Spanish motorcycle Grand Prix|ESP]] | [[French motorcycle Grand Prix|FRA]] | [[1964 Isle of Man TT|IOM]] | [[Dutch TT|NED]] | [[Belgian motorcycle Grand Prix|BEL]] | [[German motorcycle Grand Prix|GER]] | [[German motorcycle Grand Prix|DDR]] | [[Ulster Grand Prix|ULS]] | [[Finnish motorcycle Grand Prix|FIN]] |style="background:#FFDF9F;"| [[Italian motorcycle Grand Prix|NAT]] 3 |style="background:#FFFFBF;"| ''[[Japanese motorcycle Grand Prix|JPN]]'' 1 | | 42 |style="background:#DFDFDF;"| '''2nd''' | 3 |- ! rowspan=3| [[1965 Grand Prix motorcycle racing season|1965]] ! {{flagicon|Rhodesia and Nyasaland}} [[Jim Redman]] | [[United States motorcycle Grand Prix|USA]] | [[German motorcycle Grand Prix|GER]] | [[Spanish motorcycle Grand Prix|ESP]] |style="background:#EFCFFF;"| ''[[French motorcycle Grand Prix|FRA]]'' NC |style="background:#FFFFBF;"| ''[[1965 Isle of Man TT|IOM]]'' 1 |style="background:#DFDFDF;"| [[Dutch TT|NED]] 2 |style="background:#FFFFBF;"| [[Belgian motorcycle Grand Prix|BEL]] 1 |style="background:#FFFFBF;"| ''[[German motorcycle Grand Prix|DDR]]'' 1 |style="background:#FFDF9F;"| [[Czechoslovakian motorcycle Grand Prix|CZE]] 3 | [[Ulster Grand Prix|ULS]] | [[Finnish motorcycle Grand Prix|FIN]] | [[Italian motorcycle Grand Prix|NAT]] | [[Japanese motorcycle Grand Prix|JPN]] | 34 |style="background:#FFDF9F;"| '''3rd''' | 3 |- ! {{flagicon|NIR}} [[Ralph Bryans]] | [[United States motorcycle Grand Prix|USA]] | [[German motorcycle Grand Prix|GER]] | [[Spanish motorcycle Grand Prix|ESP]] | [[French motorcycle Grand Prix|FRA]] | [[1965 Isle of Man TT|IOM]] | [[Dutch TT|NED]] | [[Belgian motorcycle Grand Prix|BEL]] | [[German motorcycle Grand Prix|DDR]] | [[Czechoslovakian motorcycle Grand Prix|CZE]] |style="background:#DFFFDF;"| [[Ulster Grand Prix|ULS]] 5 |style="background:#FFDF9F;"| [[Finnish motorcycle Grand Prix|FIN]] 3 | [[Italian motorcycle Grand Prix|NAT]] | [[Japanese motorcycle Grand Prix|JPN]] | 6 ! 13th | 0 |- ! {{flagicon|GBR}} [[Mike Hailwood]] | [[United States Grand Prix (motorcycle)|USA]] | [[German motorcycle Grand Prix|GER]] | [[Spanish motorcycle Grand Prix|ESP]] | [[French motorcycle Grand Prix|FRA]] | [[1965 Isle of Man TT|IOM]] | [[Dutch TT|NED]] | | [[German motorcycle Grand Prix|DDR]] | [[Czech Republic motorcycle Grand Prix|TCH]] | [[Ulster Grand Prix|ULS]] | [[Finnish motorcycle Grand Prix|FIN]] | [[Italian motorcycle Grand Prix|NAT]] |style="background:#FFFFBF;"| [[Japanese motorcycle Grand Prix|JPN]] {{small|1}} | 8 ! 10th | 1 |- ! rowspan=3| [[1966 Grand Prix motorcycle racing season|1966]] ! {{flagicon|Rhodesia and Nyasaland}} [[Jim Redman]] |style="background:#EFCFFF;"| [[Spanish motorcycle Grand Prix|ESP]] NC |style="background:#DFDFDF;"| ''[[German motorcycle Grand Prix|GER]]'' 2 |style="background:#DFDFDF;"| [[French motorcycle Grand Prix|FRA]] 2 |style="background:#FFDF9F;"| [[Dutch TT|NED]] 3 |style="background:#FFDF9F;"| [[Belgian motorcycle Grand Prix|BEL]] 3 | [[German motorcycle Grand Prix|DDR]] | [[Czechoslovakian motorcycle Grand Prix|CZE]] | [[Finnish motorcycle Grand Prix|FIN]] | [[Ulster Grand Prix|ULS]] | [[1966 Isle of Man TT|IOM]] | [[Italian motorcycle Grand Prix|NAT]] | [[Japanese motorcycle Grand Prix|JPN]] | | 20 |style="background:#FFDF9F;"| '''3rd''' | 0 |- ! {{flagicon|GBR}} [[Mike Hailwood]] |style="background:#FFFFBF;"| [[Spanish motorcycle Grand Prix|ESP]] {{small|1}} |style="background:#FFFFBF;"| [[German motorcycle Grand Prix|GER]] {{small|1}} |style="background:#FFFFBF;"| [[French motorcycle Grand Prix|FRA]] {{small|1}} |style="background:#FFFFBF;"| [[Dutch TT|NED]] {{small|1}} |style="background:#FFFFBF;"| [[Belgian motorcycle Grand Prix|BEL]] {{small|1}} |style="background:#FFFFBF;"| [[German motorcycle Grand Prix|DDR]] {{small|1}} |style="background:#FFFFBF;"| [[Czech Republic motorcycle Grand Prix|TCH]] {{small|1}} |style="background:#FFFFBF;"| [[Finnish motorcycle Grand Prix|FIN]] {{small|1}} | [[Ulster Grand Prix|ULS]] |style="background:#FFFFBF;"| [[1966 Isle of Man TT|IOM]] {{small|1}} |style="background:#FFFFBF;"| [[Italian motorcycle Grand Prix|NAT]] {{small|1}} | [[Japanese motorcycle Grand Prix|JPN]] | | 56 |style="background:#ffffbf;"| '''1st''' | 10 |- ! {{flagicon|GBR}} [[Stuart Graham (motorcyclist)|Stuart Graham]] | [[Spanish motorcycle Grand Prix|ESP]] | [[German motorcycle Grand Prix|GER]] | [[French motorcycle Grand Prix|FRA]] | [[Dutch TT|NED]] | [[Belgian motorcycle Grand Prix|BEL]] |style="background:#DFFFDF;"| [[German motorcycle Grand Prix|DDR]] 4 |style="background:#EFCFFF;"| [[Czech Republic motorcycle Grand Prix|TCH]] Ret |style="background:#DFDFDF;"| [[Finnish motorcycle Grand Prix|FIN]] 2 |style="background:#EFCFFF;"| [[Ulster Grand Prix|ULS]] Ret |style="background:#DFDFDF;"| [[1966 Isle of Man TT|IOM]] 2 |style="background:#EFCFFF;"| [[Italian motorcycle Grand Prix|NAT]] Ret | [[Japanese motorcycle Grand Prix|JPN]] | ! 15 !style="background:#DFFFDF;"| 6th | 0 |- !rowspan=2| [[1967 Grand Prix motorcycle racing season|1967]] ! {{flagicon|GBR}} [[Mike Hailwood]] |style="background:#EFCFFF;"| [[Spanish motorcycle Grand Prix|ESP]] {{small|Ret}} | [[German motorcycle Grand Prix|GER]] |style="background:#FFDF9F;"| [[French motorcycle Grand Prix|FRA]] {{small|3}} |style="background:#FFFFBF;"| [[1967 Isle of Man TT|IOM]] {{small|1}} |style="background:#FFFFBF;"| [[Dutch TT|NED]] {{small|1}} |style="background:#DFDFDF;"| [[Belgian motorcycle Grand Prix|BEL]] {{small|2}} |style="background:#EFCFFF;"| [[German motorcycle Grand Prix|DDR]] {{small|Ret}} |style="background:#FFDF9F;"| [[Czech Republic motorcycle Grand Prix|TCH]] {{small|3}} |style="background:#FFFFBF;"| [[Finnish motorcycle Grand Prix|FIN]] {{small|1}} |style="background:#FFFFBF;"| [[Ulster Grand Prix|ULS]] {{small|1}} |style="background:#EFCFFF;"| [[Italian motorcycle Grand Prix|NAT]] {{small|Ret}} |style="background:#FFFFBF;"| [[1967 Canadian motorcycle Grand Prix|CAN]] {{small|1}} |style="background:#EFCFFF;"| [[Japanese motorcycle Grand Prix|JPN]] {{small|Ret}} | 50 |style="background:#ffffbf;"| '''1st''' | 5 |- ! {{flagicon|NIR}} [[Ralph Bryans]] |style="background:#DFDFDF;"| [[Spanish motorcycle Grand Prix|ESP]] 2 |style="background:#FFFFBF;"| [[German motorcycle Grand Prix|GER]] 1 |style="background:#DFFFDF;"| [[French motorcycle Grand Prix|FRA]] 4 |style="background:#FFDF9F;"| [[1967 Isle of Man TT|IOM]] 3 |style="background:#FFDF9F;"| [[Dutch TT|NED]] 3 |style="background:#FFDF9F;"| [[Belgian motorcycle Grand Prix|BEL]] 3 |style="background:#FFDF9F;"| [[German motorcycle Grand Prix|DDR]] 3 |style="background:#DFFFDF;"| [[Czech Republic motorcycle Grand Prix|CZE]] 4 |style="background:#EFCFFF;"| [[Finnish motorcycle Grand Prix|FIN]] NC |style="background:#DFDFDF;"| [[Ulster Grand Prix|ULS]] 2 |style="background:#FFDF9F;"| [[Italian motorcycle Grand Prix|NAT]] 3 |style="background:#FFDF9F;"| [[1967 Canadian motorcycle Grand Prix|CAN]] 3 |style="background:#FFFFBF;"| [[Japanese motorcycle Grand Prix|JPN]] 1 | 40 !style="background:#DFFFDF;"| 4th | 2 |- |colspan=18| Sources: <ref>{{cite web |title=motogp.com · 250cc World Standing 1964 |url=http://www.motogp.com/en/Results+Statistics/1964/JPN/250cc/World+Standing |website=www.motogp.com |access-date=10 May 2026 |archive-url=https://web.archive.org/web/20190530114627/http://www.motogp.com/en/Results+Statistics/1964/JPN/250cc/World+Standing |archive-date=30 May 2019 |language=en}}</ref><ref>{{cite web |title=motogp.com · 250cc World Standing 1965 |url=https://www.motogp.com/en/Results+Statistics/1965/JPN/250cc//World+Standing |website=www.motogp.com |access-date=10 May 2026 |archive-url=https://web.archive.org/web/20200327180442/https://www.motogp.com/en/Results+Statistics/1965/JPN/250cc//World+Standing |archive-date=27 March 2020 |language=en}}</ref><ref>{{cite web |title=motogp.com · 250cc World Standing 1966 |url=https://www.motogp.com/en/Results%2BStatistics/1966/JPN/250cc//World%2BStanding |website=www.motogp.com |access-date=10 May 2026 |archive-url=https://web.archive.org/web/20191205132420/https://www.motogp.com/en/Results%2BStatistics/1966/JPN/250cc//World%2BStanding |archive-date=5 December 2019 |language=en}}</ref><ref>{{cite web |title=motogp.com · 250cc World Standing 1967 |url=http://www.motogp.com/en/Results+Statistics/1967/JPN/250cc/World+Standing |website=www.motogp.com |access-date=10 May 2026 |archive-url=https://web.archive.org/web/20190616093810/http://www.motogp.com/en/Results+Statistics/1967/JPN/250cc/World+Standing |archive-date=16 June 2019 |language=en}}</ref> |} |valign="top"| {{Motorsport driver results legend}} '''Bold''' – Pole ''Italics'' – Fastest Lap |}

==Notes== {{notes}}

==References== {{reflist}}

[[Category:Honda motorcycles|RC166]] [[Category:Grand Prix motorcycles]] [[Category:Six-cylinder motorcycles]]