This is post #3 of this thread where I explain a potential modification for horse power gain " I forgot to state the displacement for the 2 options I am pursuing. 3.1" stroke = 852 cc and 3" stroke =824 cc. " I am not expecting to get much more out of 750cc but rather gain horsepower through added displacement with a 3" stroker crank and boring, resleeving the engine to larger bore. Other things that may add horsepower is new carbs and better airflow as the stock air cleaner set up is restrictive. Though the test for stated hp was done with no air cleaner installed so this is an investigation of what can be done with this engine to improve it from its stock configuration for aviation use.Oil coolers are stock on (all?) these V-twins. They do a good job of keeping the oil from breaking down and help with head cooling. To have a more substantial impact on CHTs (and, thus, continuous HP) would require a much larger flow of oil through the heads, to piston squirters, etc. Probably a high volume, low pressure oil pump would be needed in addition to the stock high pressure, low volume oil pump (plus a bigger heat exchanger, and air to feed it).
With 750cc, I think it will require "heroic measures" to achieve more than about 28 continuous HP (i.e no more than about 415F CHT, measured under the plug). Like most of the air cooled 4 strokes, heat rejection will be the factor that constrains the available continuous HP.