Originally Posted by
Capt Lou
I need help with a Saito 125. It's a new engine that I installed in a Great Planes Decathlon (Giant Scale 89" Wing Span) kit. The engine is installed inverted with a stock muffler but right angle (90 degrees) manifold. I use Powermaster 20/20 fuel and a 16x6 Zoar wood propeller. I have broken in the engine with about 1.5 gallons of fuel and it runs well with a good transition from low to high. My issue is that I can only get about 8600 RPM's at full throttle. I called Horizon and they told me that 9000 RPM's is the max I should achieve and that 8600 is the low end but not necessarily bad. I have find tuned the low end idle and that is running perfectly and I can tune the high end but only at a max of 8600 RPM's. Can anyone tell me what their experience is with these engines, especially maximum RPM's. Also, has anyone used a 17x6 propeller to improve the RPM's? thanks in advance for any assistance. Capt Lou
I used only a 15" APC on mine, but I suspect that may be about the best you are going to get for a while. You may see some RPM creeping up as you burn more fuel. The 125 is a slow turner, so it won't be a screamer. Another thing about that engine is it was difficult to keep well tuned from one day to the next until around the 2 gallon point. It was just touchy that way on mine. I would say give it a little more time, get used to the 9000 rpm range, and watch for small improvements if they develop further.
RC-Fanatic- okay, I see where you are coming from. The low speed should stay set once the engine is completely broken in and you get the needle set just right.