I have just an interesting observation here. I bought an OS .70FL by mistake. I bought it on the internet and assumed the seller had made a typo, meaning FS instead of FL. When I got it, I realized it was not the FS series I was used to seeing. I did some research on it at that point and found that it was the poor man's OS .70 four stroke engine. It had an air bleed carburetor and non-ringed piston to make it cheaper. I further found that it weighed just 19 ounces with the muffler installed (I believe that is what it weighed, but my memory is not perfect). And the most amazing thing I discovered is that it has exactly the same mounting pattern as most .46 engines. Sooooo, I was looking for a plane to put it on. I was building another Sig 4*40 at the time and decided to try it on that plane. It is a dream to fly. It has the sound and torque of a four stroke but power of a .46 two stroke. I have never had a Tiger 2, but I suspect they are pretty similar in size and flight characteristics.

In my research, I discovered this is a love it or hate it kind of engine. A little search here or on other sites will reveal a lot of criticism of the engine, but I had it and was determined to use it. It has one unique feature in that it has two nipples on the muffler, one to pressurize the tank and the other to blow some lubrication back into the crankcase. A lot of people say this engine will self destruct early, and it might. I have only flown mine a half dozen times or so, but I really like the combination of engine/airplane.