I just encountered some problems with my first 4stroke. What I was told and how that advice worked out would be worthwhile to hear.

It wouldn't start worth spit. I was told that "4strokes need 15% fuel to start good". I was using 10% so went out and bought a gallon of 15%. The engine did start better. I was at a field later where the majority use 4strokes and mentioned the 10% vs 15% deal and just about started a "Jerry Springer show" of all the guys shouting and waving their arms about how only idiots don't use 15% and how lousy 4strokes run on 10%. I was amazed, but since the engine still wouldn't start worth spit (it flooded almost every attempt) but was running somewhat better, I guess I could understand. But was amazed at the passion those 4stroke guys showed.

So I was told that 4strokes need 15%. The word was "need". I didn't notice that mine was any easier to start with 15%, but it did run better with 15%. It was easier to needle the engine and it didn't deadstick as often with the higher nitro. I'm told the higher nitro works better because it runs the engine hotter and that keeps the plug hot though the non-firing cycle. Which is also the reason you need 4stroke glowplugs. They hold their heat better when washed down with fuel in the nopower cycle.

So how do they start? My first one didn't. Not often anyway. I was at that "Jerry Springer Show" field when that crowd jumped me for not being able to start my 4stroke easily. So I let some of them have a shot at it. They didn't do worth spit either. What they did do was start up another "excited chimps in the zoo" deal when one of them noted that "4strokes need to be side mounted or upright". All of them took up the chant, so I'm guessing there is some truth to that. I know that the installation of mine was inside a cowl that gave no access to the venturi. It was a downdraft carb and being upside down would flood in a heartbeat. After ultimately swapping out the 4stroke for a 2stroke, the two stroke showed no problems being upside down, so there is some truth to "don't mount a 4stroke upside down". Yeah, I know lots of people do it. But that one didn't like it.

And while dealing with my 4stroke, the sucker ruined a couple of spinners that had plastic backplates. The engine had a tendency to backfire and a couple of backfire bouts were bad enough to strip off the serrations that help hold the spinner/prop solidly. I can't use those now even with 2strokes.

I'm very experienced with 2strokes. My experience with 4strokes so far would suggest to me that.......

They need 15% fuel.
They should be mounted sideways or upright to insure decent starting.
They might ruin a spinner or two.
Make sure you use 4stroke glowplugs.