In 2017, hp race development powered Ty Masterpool to 2 supermini championships aboard a TM 100. It was a true 100cc's of size and on our dyno it produces just under 30 hp in race trim. At that time, the KTM was it's previous generation engine with an archaic 105 cylinder that was at least 20 years old in development. A lynks 112 in that year made about 27-28 hp in full race trim on our dyno. A really good Pro Circuit kx109 would tickle about 27.5 that year, and the best 150r we ever built about 10 years ago was 25.
In 2017 our unobtanium 85cc mod package (sold a very few of these) used a custom modified pipe, huge amounts of R&D, and could knock down similar numbers as those aforementioned supermini builds. But the larger engines did have some power width advantages. To get our KTM supermini package dialed, we generally stuck at 105cc, our cylinder had huge amounts of epoxy within the transfer ports to reshape and redesign the ports more modern like our good 85's), we had a specially welded and reshaped exhaust port, and a special redesigned head sealing surface with orings moved to the head, the inner oring groove filled in on the cylinder, and a the cylinder beefed up to prevent the base nut tabs from cracking off which occurred often at good power levels. A really good super ktm could knock down about 31 in this trim - and was truly amazing for what is started at (out of the box, about 21-22hp on a 105 of that era for us). The cost of doing this was huge and i'll never do another one again!
Now - while it's not easy, eclipsing that power mark requires far less effort, as ktm has really done a fantastic job on the new cylinder
Back to 2017 - Ty raced on the same exact track on back to back motos as 250A/Pro class, there was no track work between, and that year was the year of Justin Cooper. If you go look, Ty aboard his supermini was able to turn his fastest lap about 1 second a lap off cooper's fastest lap on his Yamaha 250f. On identical tracks, back to back.
It was a spectacle to see - and I truly feel no one has ever turned any size motorcycle better than Ty did that year - he was little at the time and fit that size bike perfectly.
So let's talk basic power to weight numbers!
A KTM 112 is approximately 160 lbs in race trim. Let's factor in a supermini rider at 120 lbs (ty was 105!) and you have a combined weight of 280 and a power output at the time of 29.5 for a power to weight of 9.49 lbs per HP
A Yamaha 250f of the time in race trim was about 233 lbs, and a rider would be around 140lbs
Combined weight 377, on our dyno a Yamaha of that era in cooper race trim was about 41 hp (yeah yeah sure, 50hp - nope....we dyno'd some bikes of a Texas pro on that same build)
That's a power to weight of 9.2lbs/hp.
The edge here goes to the 250f, however you also need to factor in the additional rotational inertia of the 250 wheels - which basically evens them out. Now - that said, the 250f has MUCH wider power which allows it to have a higher avg power output at all times...
However with the right rider (Ty) on the right track (loretta's) we got to witness a supermini get really really close to the next prodigy's best lap time. Pretty cool, I'd say!
What about at 33 hp?
Well, now the super gets the edge with 8.48 lbs per HP. If you paid attention in physics - F=MA and when you have a low M, and a big F, your acceleration A is the best!
If you saw our 2022 factory edition KTM250f video, you'd see we have managed to squeek out 46 now with our ECU, and VP racing fuels Pro6
I weigh 165 - bike weighs, in race trim, 230 ish - for a power to weight of 8.58 lbs per HP.
I can tell you this - I don't think I'd want to drag race our supermini build on my 250!!!! Maybe that's a video for another day...