The sound very much reminds me of an old fashioned stationary engine. When I was doing the small holder farming thing back in my 30s I owned a hopper cooled cast iron horizontal stationary engine. It wasn't very big and it had an open crankcase too with drip oilers on the bearings. I notice that the compression ratio was only 4:1 so it looks like it shares the same soft tuning as my old hopper cooled engine did. That would be one reason why it doesn'tt need a muffler to be quiet as my old engine never had one either and it chuffed away pleasantly to itself in exactly the same way.I said the same thing, Intrepid, about the sound. Is beautiful.
Then asked if he had done an "indestructibles" when I meant to ask "instructables" Snork. I am gonna go with typo, speel check or "I meant to do that"
Tom, in the comments, some one asked and he said he mixed some 4 stroke oil in the gas. I was thinking some kinda McCoy oilier on the cam that could leach into the combustion chamber might be a thought? Then thought a fish bowl/bubble gum glass oil res.....
Dunno but that thing is just an uber cool little power plant