How fast - on 50cc?!

[Ivan]

THe 17 gears was crucial because crank case compression was altered it had a high crankcase compression and made the engine to peaky and unrideable they needed more gears for a better power spread.
Porting of the 2 stroke engien also weaves good power
Internal gearing defines your gear setup then your final drive gearing, plus the frame weight rider ability,

Its all part of it

Id struggle to see a 50cc Honda GP get near 200 the speed of there 125GP bikes??????

[lb99]

85mph is more than 135kph. How is it, that I'm struggling to hit 140kph in a 26hp machine, ?

your bike should smoke 140, more like 150+ with big balls down a bit of a hill, CB250rs is a prtty quick single, maybe yours isn't making 26bhp?

[Coyote]

With some bikes, especially ones that require some nursing, you do need to know how to ride to get the best out of them, just winding the throttle up isnt always enough.

My 2 RG's have been good for over 100. The one I have currently got will do 120kmph if I get a draft or downhill for the gap in powerband between 5th and 6th! Once at that speed and in the band it will hold it. New piston and rings might fix that issue or another tooth on the rear sprocket. The other was lower geared and would do 110. Bloody good fun having to work them so hard. 82 gear changes between karori and island bay! (and thats with a clear run!)

Interesting, I've yet to ride such a bike

That's one of the great things about the small light bikes, it's rewarding when you get the shifts just right

[eliot-ness]

The first pic is the RC110 minus fairing, this was not the factory racer but was very close. It was produced as a limited edition over the counter racer in 1962. Specs. DOHC 4 stroke single cylinder. Bore 40.4mm Stroke 30mm. HP. 8.5bhp. 8speed gearbox. Weight. 62 kgs Top speed 88mph. Cost in 1962. 380 pounds. Value now Approx 25,000 pounds.

The second pic is Ricardo Tormo onthe Bultaco, 1975 Two stroke with monocogue frame. After 1969 rules were changed. 6 speed boxes were the limit. The Japanese had pulled out leaving the field open to the Europeans. The Bultaco was originally a Dutch bike, but after a brief move to Italy was bought by Bultaco who, with rider Angel Nieto in 76/77 and Ricardo Tormo 1978 won the world championships. Bulaco went bust but had built a few replicas, one of which won the 1981 championship with Tormo aboard. These bikes had a race average of over 100mph at tracks like Spa. In order to keep the engine within it's 13,000 to 16,000 power band corners had to be taken almost flat out, only backing off when the tyres started to roll on the rims. Cornering speeds were higher than the 250cc class. Not all riders were midgets. Hailwood rode the Kreidler at the IOM in the mid 60s
Bultaco specs. Water cooled rotary valve 2 stroke single. Bore 40mm, stroke 39.5mm. BHP 18. Gearbox, 6 speed. (cassette type). Weight, 55.5 kilos.
Top speed, Approx. 118mph

[Kickaha]

, but after a brief move to Italy was bought by Bultaco who, with rider Angel Nieto in 76/77

The Nieto family is still very much involved in GP racing

[speedpro]

In NZ I think Pete Sales still holds the 50cc land speed record on his GT50 at something like 85mph.

[quickbuck]

In NZ I think Pete Sales still holds the 50cc land speed record on his GT50 at something like 85mph.

He may well do.
I do know of somebody (that lives quite close to me) who wanted to break it using an old aircraft drop tank....
Not sure if that project is still underway though.

[nudemetalz]

I raced an RD-50 at about 1988-89. Clocked at 110-115km/h from memory. Weighed virtually nothing. It had a very peaky powerband and needed lots of clutch work out of corners

Here's a couple of pics of it.
That second shot is me on the sweeper onto the straight at Levels. I was nearly at maximum speed there, so you can imagine the poor wee engine pulling 12,000rpm all the way. I had problems with it nipping up on me, unsurpisingly !!!

[nadroj]

yeah Pete still does though I'm sure I could beat him with some decent gas & some comprewssion, shit this keypoad is crapy. Ivan I wa just wondering if you were dead as haven't herardmuch of you & no show at Brooklyn.


anyway hello from the KB gathering, guess-who & hello Mike.,, Hope things are going well with the new job,

PS this isn't my log on, just free for all on someone elses at the rally

[xwhatsit]

your bike should smoke 140, more like 150+ with big balls down a bit of a hill, CB250rs is a prtty quick single, maybe yours isn't making 26bhp?

Down a hill, yeah, I imagine I could get close to 150kph. On the flat though, 140kph is where it tops out (convenient for avoiding licence suspension lol). I wouldn't be surprised if it's a little bit down on power, the valves need a better seal, and either the ignition is over-advanced or it's running lean, so there's potential for improvement I think.

The first pic is the RC110 minus fairing, this was not the factory racer but was very close. It was produced as a limited edition over the counter racer in 1962. Specs. DOHC 4 stroke single cylinder. Bore 40.4mm Stroke 30mm. HP. 8.5bhp. 8speed gearbox. Weight. 62 kgs Top speed 88mph. Cost in 1962. 380 pounds. Value now Approx 25,000 pounds.

The second pic is Ricardo Tormo onthe Bultaco, 1975 Two stroke with monocogue frame. After 1969 rules were changed. 6 speed boxes were the limit. The Japanese had pulled out leaving the field open to the Europeans. The Bultaco was originally a Dutch bike, but after a brief move to Italy was bought by Bultaco who, with rider Angel Nieto in 76/77 and Ricardo Tormo 1978 won the world championships. Bulaco went bust but had built a few replicas, one of which won the 1981 championship with Tormo aboard. These bikes had a race average of over 100mph at tracks like Spa. In order to keep the engine within it's 13,000 to 16,000 power band corners had to be taken almost flat out, only backing off when the tyres started to roll on the rims. Cornering speeds were higher than the 250cc class. Not all riders were midgets. Hailwood rode the Kreidler at the IOM in the mid 60s
Bultaco specs. Water cooled rotary valve 2 stroke single. Bore 40mm, stroke 39.5mm. BHP 18. Gearbox, 6 speed. (cassette type). Weight, 55.5 kilos.
Top speed, Approx. 118mph

Beautiful, mate, both those bikes. The non-factory racer RC110 was the CR110, wasn't it? That's the one they recently made a reproduction of (with a 100cc+ engine though, to get the same performance as the 50cc without crazy rebuilds), and are selling in Japan for ludicrous amounts.

Why did this class disappear? Did it just become irrelevant? Wiki says the reason they started racing was that there were heaps of 50cc bikes just lying around and in production, so it was very cheap to get involved in. Not really the case today, I'm sure the amount of technology they'd use today wouldn't come easily, but it would still be cheaper than maintaining a 125 or 250 at race spec.

[kensuem]

http://www.vintagebike.co.uk/
go to the above site and click on 'Sounds',then look for the sound of the 50cc pack.there are also some other great sounds there.when i did the video of my GN250,I tried dubbing the sound of some of the classic racers on to my Gn tape,but decided no one would believe me!On my way to school as a 15year old,I used to pass a bike shop which sold Itom 50cc bikes.The great Bill Ivey used to work as a mechanic in that shop,and his Itom race bike was often on show in the window.I was too big a build for a 50,but ended up buying an A7 Shooting Star from them instead.

[Bass]

In NZ I think Pete Sales still holds the 50cc land speed record on his GT50 at something like 85mph.

Where is he these days?
I used to know him quite well but I haven't seen him in 30 years or thereabouts.

[Forest]

Knowing how to ride doesn't increase top speed in a straight line. Any chimp can wind the throttle up

A good rider can alter the shape of his back to help smooth the air-flow over the top of the bike. It takes some skill to do this well.

[speedpro]

Where is he these days?
I used to know him quite well but I haven't seen him in 30 years or thereabouts.

Total Motorcycles just south of Palmerston Nth.

[N4CR]

1. cagiva mito 125 gasses zxr250 in top end most of hte time 200kmh with the right setup wtfpwnd. 7 gears of ***. go get a refund on your rg50's. rs50 4tw

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