Al from 44T proving a KTM 1290 Super Adventure is a perfectly good trackday weapon... Even on typical 90/10 Adventure tyres...
I did my first track day last year on my 1290 Super Adventure only a few weeks after having picked it up. It was only Mallory, but it's still surprisingly capable on track. I was in the intermediate group, was certainly one of the quicker ones in the group on the day. Which doesn't say a lot to be fair, a fast rider would still have lapped me on a CB500 I expect! But the bike wasn't holding me back for certain... And on the road it's a weapon!
It's literally all piston speed... Ducati were running 116m pistons in a Panigale 1299 engine to beyond 12krpm 8yrs ago... The new 698 Hypermotard is essentially one half of a 1299 Engine, albeit with a slightly longer stroke and a more road friendly tune, and that's got a rev limit north of 10k and 9k mile service intervals...mangocrazy wrote: ↑Sun Dec 03, 2023 9:50 pm It's primarily piston speed that's the limiting factor, so KTM have dodged that by keeping the stroke the same and just increasing the bore. I do wonder how much further they can go with the current design though.
The only real problems with massive pistons becomes balancing them. More smaller pistons are easier to balance than fewer larger ones, and thus more reliable at higher rpm. If you can balance huge pistons well enough though, then you won't have any problems, and until they introduced the V4 engine, Ducati proved that high revving large piston engined bikes were no problem for them.
A "Peak Mean Piston Speed" of around 30m/s seems to be the limit for incredibly well built and balanced modern performance engines before they start shaking themselves to pieces. For a long time, 25m/s was considered the max. I remember BMW making a mockery of this when they introduced the S85 V10 in the E60 M5 in 2005, F1 cars at the time had PMPS of under 25m/s and the M5 exceeded this and with normal road car service intervals too! Audi then upped the game with their V10 in the R8, which is strangely undersquare for such a high revving engine, and in its most potent form, has a PMPS of over 28m/s and again, normal road car service intervals!
Motorbike engines have an easy time relatively speaking, as they don't require the same kind of low down torque that car engines do, so mostly they're designed very oversquare anyway. The 698 Hypermotard engine that everyone is getting googly eyed about as it's the first production Single cylinder engine to rev beyond 10k actually has a pretty low PMPS of around 21m/s for instance... Cosworth achieved that figure back in the 1960's with the introduction of the DFV!!!
Top Fuel Drag engines are where it's at in this respect... OK they may barely rev past 8k, but with a 4 1/2" long stroke they're achieving PMPS of over 30m/s... For a few seconds... Running so much fuel as to be almost at hydraulic lock... Before the engine is torn down and rebuilt again!
I know some "enthusiasts" of other hobbies who will pay more than that per gram! Makes motorcycles look like an incredible bargain by comparison...
