Fisrt off, did you get the instruction manual with your engine? If not you can download a pdf copy from http://www.osengines.com/. This will answer most of your questions about break in and starting.

As far as break in is concerned, the conventional wisdom is to not run it fully 4 cycling rich. However, strangely enough OS's instruction manual for this engine actually says to do that on the first couple of tanks. I wonder if the fact that these engines are ABN (nickel) not true ABC has any effect?

The whole break in process will take a while, I think I ran about 1/2 gallon (about 2 litres) through mine real rich for 5 minute runs before I flew - slowly leaning it in after each tank. I've now got about 2 gallons (~8 litres) through it and turning a 10x7 prop on 15% nitro/18% oil fuel it is set exactly 1 turn out open on the main needle around 500 rpm below full lean. Also, I needed to close the idle needle quite a bit to get a good reliable idle.

Another thing, what percentage of oil are you using? The manual says 18% minimum is mandatory. Many commercial fuels here in the US are lower (16-17%) so I adda few ounces of castor per gallon for safety.


I've found that I can usually get it to hand start once its primed well. the method I use is:
1. Throttle open full
2. finger on card, flip until fuel reaches carb
3. flip 1-2 times more
4. finger off carb, throttle at idle
5. flip 2-3 times to get mixture into cylinder

Now attach the glow driver and flip to start. This method sometimes fails on the first start of the day but is usally sufficient thereafter.