50cc World Speed Record - 144.891 mph!

[hydroplay]

I seem to recall Honda raced a twin cylinder 50cc 4-stroke in the 60's. Ran 22,000 RPM and beat the 2-strokes of Yamaha and Suzuki.

They also had a 5 cylinder 125 version that ran similar rpms. I read somewhere that carburetor jetting was so critical that when the bike went into a shaded area of a race track, it would miss because the slight change in temp was critical to the carb jetting at those rpms.

[Original Looper 1]

Hi,

I've posted this link a while ago but it's worth reposting. It's a link to a British site that has the original recorded sounds of some of these remarkable road racing, small displacement motorcycle engines in battle.

http://www.vintagebike.co.uk/Sounds.htm


Enjoy!



Paul A Christner


PS: Listen carefully to the 1967 Suzuki 50cc. WOW!

[Original Looper 1]

Imagine: 60,000 combustion cycles per minute at 20,000 rpms.


Suzuki RP68 50cc 3 cylinder

At the end of 1966, Honda withdrawal from the 50cc and 125cc classes, which means Suzuki, had no fears of real competition for 1967. The Kreidlers, Derbi’s and the Dutch Jamathi had not much chance for real treatment to the Suzuki. The riders Anscheid, Katayama, and Graham get an improved version of the two stroke twin.


The water cooled RK67 which gives a power output of 17,5 hp at 17.300 rpm, via a bore and stroke of 32,5x30 mm, has rotary disc intake with 22mm carburettors installed. The compression rate was 8,5:1 and it needed 14 gears to keep the engine in his power band. The weight was 58 kg and the little bike had a top speed of 176 km/h. Hans Georg Anscheid becomes world champion before his team mates Yoshimi Katayama and Stuart Graham.


At the end of 1967 Suzuki turns up with a sensation by presenting a brand new three cylinder, afraid of the possibility Honda would bring out, like rumours has it, a three cylinder in 1968.


The RP68 was a very interesting machine, it has 2 lying and 1 standing water cooled cylinder, behind the standing cylinder is a waterpump installed. The bore and stroke were 28x 26,5mm, the little engine has rotary disc intakes, and was given up at 19 hp at 20.000 rpm, good for some 200km/h. It had a power band of 500 revs and it needed 14 gears.



You can read the rest of the article about this fascinating technology, way ahead of it's time, at:
http://www.yamahaclassictwostrokes.n...d=22&Itemid=32