250 vs 250

rmoto003 :

No one is saying a (naturally aspirated) 4t of equivalent displacement ( and 'tune' for an application) will make more HP than the same displacement 2t. Though, there is so much more to come for 4ts - and 2ts if they are continued / restarted in development.

The point within Dericks post that people tend to miss are the simple words he placed in brackets - "(in MX Form)".

It comes down to what is actually usable by a rider, in the racing format the bike / engine is used in.

It's not wildly hard to get 60+HP from a single cylinder 250 2t - heck, even by a 'hack' tuner. Hell, the last 250 twin Road Race Engines were getting 105 /112 HP, if #s were to believed. But, that 'hack' tuner (of the 60+HP 250 2t) would probably produce an engine with the usable power range the width (not even the length) of a Gnats Dick. And a life span of about the thickness of said Gnats short and curlies. And it would Not something remotely rideable and competitive. A Good Tuner? - well that's another matter, but I still think it wouldn't be an easy engine to use.

I've seen claims that an Aussie riding a 250 2t KTM / KTHusky was on a 62+HP bike, one season. Not that hard to get that number, but it would be a bit of bastard of a bike to ride, even for a (very) high level rider.

I remember David Thorpe having a column in Dirt Bike Rider, decades ago, writing about his pre-season testing of his RC/ CR500 engines. With He, and the other riders having to go up against the ever present Honda Engineers ethos of More Power is Better! Figures in the 80s / 90s HP thrown around - in an era where the 4 cylinder NSR500s were getting 160 / 175 + HP. With he, and the other riders going back to their high 60 / low 70 HP numbers. Because any more than that made the bikes damned near unridable, with inferior lap times being generated.

The '10HP' difference referred to above between a YZF250 and a YZ250 are from a few years ago. Now, YZFs, depending on the Dyno / the Operator, are being listed between 40 / 43 HP, I think . On the Same Dynos / with the same Operators, the KTM / KTHusky show around 45 / 46 , and the KXFs between the YZF and Austrian bikes. With the YZ250 remaining the same, bar jetting and muffler, for well over a decade, at 44 /46HP.

The 4ts get their HP over a huge Rev range. It's the time honored way of getting ever more power - Revs, Revs and More Revs. It's why, during the Sixties, things like the Honda Six's, 5s, 4s, and 3s (for various capacities) were developed - not forgetting the V4 Yamaha 125 and 250 2ts, and the Suzuki V4 / Square 4 125s (and 250s, I think) 2ts. Well before the 4 cylinder 500 2ts became the 'std' in 500GPs.

Look to one of the most basic differences between a 250 2t and a 250 4t: a near universal std stroke on a 250 2t is 72mm - the KTMs / KTHuskies 4ts are, I think, 52.8mm, and the new Honda is something like that - the others not far behind in such short strokes. That near 20mm difference in stroke makes for a massive difference in piston speed at the same RPM. That, and charge delivery / internal flow dynamics / exhaust dynamics keeps 250 2ts at the 8 / 9k (give or take a few hundred revs) Max power useable rev level, whilst the 4ts can have safe / usable revs into the 13 / 14 / 15K revs. With quite a few Tuners / Engineers going for , and getting, far more.

It makes for a hell of an effective rev range difference between the 2 types of ICEs. So, there's a lot of 'ride-ability' to an equivalent sized 4t, when tuned for the same purpose. Mind you, said 4t has pathetic levels of Torque - as shown in the previous post - compared to a 2t. I truly laugh my arse off when I read people saying how much more Torque a 4t has. People, it's purely down to the Capacity advantage given to them, that is all.

And the revs people have to use on 250Fs, truly make for some funny / fearful sights when riders of such bikes, get on a 250 2t and try to ride it the same way they do the 250F.....

250Fs - well all sized Performance 4ts - are truly amazing things Now.

I get on a 250F nowadays, and, being honest with myself, I doubt I could get faster lap times, be it on an MX track or an Enduro Special test - or just be 'quick' on a Trail Ride on anything other than the 250F. But, I ride, and will continue to ride, my 500cc 2t, that probably never gets above 4K revs on my usual rides. It's a Big Cuddly Teddy Bear that I love, and I'm so far past being / trying to be fast, it's not funny.

I'm Not a 'Hater' of For Strokes - just the piss poor Handicap rules, that persist at the highest levels of our sport.

It's just pathetic that Equivalency is Not the standard in All levels of racing. That it is not the 'norm', truly shows the manipulation of the rules, and I daresay the intimidation (by some manufacturers) or 'payoffs' of a few of the Highest level controllers of our sport.

It's about 10 years past the time for this BS Handicap Class Racing to have been given the boot.

Electrics fit into the political correctness narrative that has been jammed down our throats for the last several decades- the quality of the racing, and overall excitement level be damned.
The tree huggers from CA, NY and others will rejoice that a previously endangered butterfly species will be exponentially better off if we could only get rid of environmentally unfriendly 4 strokes, not to mention unthinkable 2 strokes.

Your argument against electrics uses common sense and testosterone as a rebuttal. Neither of these is acceptable in today's environment.

I just wanna see a highly modded 250 smoker vs a factory 250f. plz lord