I stand corrected. The weight I specified for the OS .91 is WITHOUT muffler. I cannot find the spec. for the muffler weight. but I would imagine that it would put the engine a few ounces heavier than the Saito 100. Not sure though. At any rate I would estimate that the power to weight ratio of each engine is about the same.

Another thing I would like to point out. My Saito 100 is rated at 1.8 hp. I can get about 1.7 hp out of it. My 2 stroke .46 is rated at 1.7 hp but I can only get about 1 hp out of it running a prop that will give enough thrust such as an 11X6. I could put a 10X5 on it and get more rpm and more calculated hp output but the smaller diameter would produce less thrust and wouldn't be practical. So the lesson learned is that you can get about 94% of the rated hp out of a 4 stroke but only about 60% of a 2 stroke's rated hp.