Europe has a significant motocross sidecar (sidecarcross) racing thing going. One of the staple engines is the Zabel 700cc single cylinder two stroke. https://www.facebook.com/ZABEL-2-stroke-Engines-Germany-306256496068274/ https://en.wikipedia.org/wiki/Zabel_(engine) It is made in Germany and has been for years. This engine appears to be 78 HP stock and low RPM. They appear to be easily souped for bigger power. Several companies build complete dirt bikes for this engine. The engine can be purchased new and used ones are available also. The engine started as a continuation of the 500cc Maico motocross engine. Wouldn't it be great to build an "unlimited displacement single cylinder" class road racer with one of these. Of coarse I would have to also mention 500cc versions of the 300cc KTM also. I know that there are current 4 stroke single cylinder engines that can probably make this power also but ,,, TWO STROKE.
Based on old Maico 500 so probably no counterbalancer. I imagine on a road course it would quickly turn your cartilage to jelly from fibration at WFO. Motocross not so much a problem, continuously off and on throttle. Braaaap! Braaaap! But don't let me stop you!
Two strokes other than diesel get much less efficient as displacement increases. The big bore kits usually exacerbate the problem by giving the often fuel starved motor the shittiest possible transfer port geometry and bore/stroke ratio. And fitting a proper pipe for that size is near impossible. Gonna look like coffee cans welded together to get the right diameter and volume. Bet the sound is awesome though, the big dirty two strokes make a racket like nothing else. Off to YouTube to look at dirty sidecars.
