2 Reasons, probably:-
1) They were all designed as RACING engines. The Rotax (horror!) was designed as a LESURE engine. Eve Rotax will confirm that. They never MEANT you to race it. Be fair: it was designed by Aprilia as a feeble-bike motor and Rotax snaffled it!
2) Because we ran them so much harder! During the peak of the 100 National/International era, engines were like an 'arms race'. Karting was popular and PROFITABLE and you could do almost what you liked to the motor (there were of course limits) but, with a huge range of engiunes to choose from, each manufacturer who wanted to 'play the game' lived or died on the speed of their motor. We revved the NUTS off them so they were unreliable. However, had we developed a PROPER Rev Limiter, we could have kept the similar sort of power bu with a 10 times longer break beetween rebuids.
Of course, I AM aware that I am now so old that I think EVERYTHING was better in my day.....
(That last bit IS a lie!)
I am still never happy about Rotaries being called 4 Strokes but, Paul (boss of Aixro) has assured me, personally, that it is. No matter how hard I stressed that there ARE no 'stokes' in a Rotary... he still insisted.
Remember, 2 strokes have suck, squeeze, bang and blow.... just above AND below the piston. So S,S,B,B can't be the 'definition' of a 4 stroke! The other 'definer' could be having an oil-filled crank case.... but the Aixro doesn't and there are oil filled crank-cases in somke 2 strokes.
Basically, I'd argue that we now have THREE types of motors (or more), 4 stroke, 2 stroke and Rotary. That's a lot simpler than trying to sqeeze the Aixro into a class that doesn't fit. Remember that the Aixro has oil in the fuel..... like 2 stroke!
Ian
|
|