Remember we were talking highest revving engines?

Barry Sheene and a 50cc twin.

https://www.youtube.com/watch?v=9WQxc5gyzAU

Curmudgeon wrote:

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!'

If the engine was out of the race version it would probably rape a modern day 600cc class sport bike if they geared it correctly.

FWIW, MotoGP bikes rev really really high .....or they did. They either got limiters last year or this year.

I wonder how many gears before friction loss outweighs the benefits of being on the pipe with 50 cc to work with.

yamaha wrote:

Curmudgeon wrote:

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!'

If the engine was out of the race version it would probably rape a modern day 600cc class sport bike if they geared it correctly. FWIW, MotoGP bikes rev really really high .....or they did. They either got limiters last year or this year.

Answering my own query, the zx2r was a 4 stroker that only made 45ish HP.....I still want one for the noise though.

Ok I happen to be a small bore GP bike nerd:

First the highest revving thing I know of, the oval piston 8 valve per cylinder Honda NR500, not small bore but it revved to 25,000 rpms. It might have even gone to 27k

Honda RC 149 5 cylinder 125cc GP bike made 34hp at 21,000 rpms. Look up 5 cylinder Honda 125 the sound is awesome.

Two strokes:

The last of the 50cc GP bikes, Kreidler Van Veen were up to about 24hp at 16,000 rpm and at Spa were hittin close to 125mph.

The early single cylinder 50cc bikes like Suzuki RK67 made 16-18hp at about at around 17,000 rpms with the aforementioned 14 speed gearbox. Some factory riders were sent home on street models equipped with these gearboxes so they could become proficent with them. They had power bands that were only 400 rpms wide.

The 80cc GP bikes revved about the same and I think were up to 28hp.

The FIM changed the rules in 69 in response to things like Honda 5 cyl 125s and Yamaha V4 two stroke 125s to single cylinder 50s and 125 twins. The last of the 125 twins like Garelli and Morbidelli were up 45-48 hp at the rear wheels, when the rules the 125 single the last of them were getting 50 whp and Valentino Rossi was clocked at 154mph. So the little tiddlers were pushing over 400 bhp per liter.

My Honda 125 GP bike turned 13,000 rpms and went 130mph at Riverside.

Loved these little bikes and would love a Kriedler but at $8000 or more not likely to spend the money.

     Tom

I've been looking for an FZR400 project for a while, that's how you keep up with 600cc bikes!