Remember we were talking highest revving engines?

Some time back there was a thread about high revving engines and I mentioned the Tohatsu 'teacup racers' of the early 1960's. Well, here is a video of what appears to be a beautifully restored example:

https://www.youtube.com/watch?v=BfNnBoFnpg4

EDIT: I went back and watched the video a few times, noticed that the tach STARTS at 7000 RPM.

That thing is TINY. Everything is spindly; hard to imagine racing them! Pic I found of one in action in Europe, circa 1965:

That thing is like a bicycle with a weedwacker attached to the sprocket. I wonder how little it weighs.

Weedwackers are generally around 23cc, so it would be more like a bicycle with TWO weedwackers on board!

50cc TWIN? What the heck...

I had a '77 Honda CB400F SuperSport. It pales in comparison to the 50cc twin, but I think it had a 10,000 rpm redline and that astonished me for the time period in which it was made. I gave it to a friend and it's still sitting in his shop. It's gotten a little dusty...

Knurled wrote: 50cc TWIN? What the heck...

Dude. Suzuki was working on a 50cc SIX CYLINDER. From what I have found over the years the 50cc version never made it past the 'running prototype' stage but they along with Honda produced 250cc 6 cylinder GP racers. Mike 'The Bike' Hailwood won two world championships for Honda on the RC166, a 250cc six cylinder four stroke.

Suzuki did produce a 50cc 3 cylinder...
...with a 14 speed transmission.

Hell, it was all I could do to keep up with where I was with the six speeds.

Oh, and power output? Most reports on the teacup bikes said (depending on make) they made between 19-21 HP and of course no one would talk about torque 'cuz there wasn't any. But the HP figures work out to 380 HP per liter. Wow.

Pic of a Honda RC115 50cc twin pistons and crank:

Yes, those are valve reliefs because it was a four stroke. Honda has always been a proponent of the four stroke engine, in 1964? the FIM limited the 50cc class to two cylinders, thus what you see here was born.

Sorry, these tiny bikes fascinate me. Isle of Man, over 100 MPH: https://www.youtube.com/watch?v=s4PA8VFpUlc

Check out the tach! It STARTS at 5,000 RPM.

https://www.youtube.com/watch?v=B9K5YAWgiKY

I have a friend who collects 50 cc road race bikes. They're small even for me and I'm 5'7"/145

Curmudgeon wrote: ...with a 14 speed transmission. Hell, it was all I could do to keep up with where I was with the six speeds.

Wear out your ankle after two laps. Jeeeeeez...

from http://www.speedhunters.com/2015/01/kiwi-flavoured-lemon-jun-synergy-brz-v8/

A BRZ with a Synergy V8 aka two Kawasaki 1,200cc four cylinder motorcycle engines combined at the crank. red line is 11600 rpm

listen to the glorious noises https://www.youtube.com/watch?v=XCwMX-cFKdk

I wonder how they would deal with my 230# lard-butt?

Curmudgeon wrote: Check out the tach! It STARTS at 5,000 RPM. https://www.youtube.com/watch?v=B9K5YAWgiKY

I like the closet-sized dyno shop

In reply to Curmudgeon:

Those pistons are hilarious! Now youve got me watching videos of these bikes.

My 1990 Ninja 250 has a 15,500rpm redline

LISTEN! RC166 content.

Knurled wrote:

Curmudgeon wrote: ...with a 14 speed transmission. Hell, it was all I could do to keep up with where I was with the six speeds.

Wear out your ankle after two laps. Jeeeeeez...

I once counted how many times I shift my 150 on our woods course. It was just around 100 shifts per 20 minute lap. I ran a 6 hr hare scramble the week after

In a motocross race, I normally shift 50 times per 2 minute +/- lap time.

That's more speeds than the new SRAM mountain bike kits!

Kawasaki ZX2R at 20k RPM: https://www.youtube.com/watch?v=FJ8R4tYbX5w

Hungary Bill wrote: Kawasaki ZX2R at 20k RPM: https://www.youtube.com/watch?v=FJ8R4tYbX5w

I would love one of those! Such an awesome race class

GSX-R250 did 19,000 stock, CBR 250 was 18,000 and FZR250 was 18,500

Hungary Bill wrote: Kawasaki ZX2R at 20k RPM: https://www.youtube.com/watch?v=FJ8R4tYbX5w

'All this thing is is noise. But man it sounds great!'

Curmudgeon wrote: Oh, and power output? Most reports on the teacup bikes said (depending on make) they made between 19-21 HP and of course no one would talk about torque 'cuz there wasn't any. But the HP figures work out to 380 HP per liter. Wow.

For a modern, production example, look at the water cooled 85cc 2 stroke dirt bikes, 20-25hp out of 85cc on the newer ones, stock.

How about a 4 cyl. 50cc engine:

https://www.youtube.com/watch?v=NiNfTsVXJq8