thanks a bunch 1QuikSport that page has lots of good info i will definitely be checking that out since it relates to my engine specifically.
i did get to run my boat again today and it ran lots better. i had been watching some videos on youtube about how to tune a nitro engine. i think i learned enough to make it run better than it was before and im happy with how its running now for the most part but it still sometimes dies for some reason and gives little or no warning that its about to die. so i am trying to figure out why and how to fix that. also im thinking my boat may be a little big and heavy for this motor. not sure the exact weight atm but ill get it weighed this week sometime. i wish id had a camera to record the run i made today. it was really screaming there for a while then i got chicken and slowed down.
Airplane engines are rather easy to tune, generally. ST engines (based on what I've read) are good running engines, but can be a little tricky to tune. The General rule of thumb is you tune the main needle first setting to peak RPM, then richening the needle 2-3 clicks. Then set the idle mixture to get a clean transition then richen about 1/16th turn. If you adjust one needle, you have to adjust the other since one usually affects the other at certain throttle settings.
If its just dying for no reason, I'd suspect air bubbles in the fuel line from vibration. Ensure the fuel tank is isolated from the hull - any part of the tank touching the hull directly will/can cause the fuel to foam up a little bit leading to air bubbles in the feed line and ultimately causing a deadstick. If you havent replaced the fuel lines on it yet, I'd suggest doing so - Old fuel line can crack or get pinholes in it leading to air bubbles as well. Watch the fuel line to the carb while the engine is running. Throttle it some while watching the fuel line looking for bubbles. A whole bunch of small bubbles usually turn into one big one and a big enough bubble not only will lean your fuel mixture but can cause your engine to just quit for no reason especially at higher RPM.