Originally Posted by
FormerDairyFarmer
Excessively rich in my statement means over primed, don't even think about telling me you haven't done that. Running rich won't kick the prop off. You sure do like to fight, why is that? As far as commenting in a Saito thread, engines is engines, the name on them doesn't change much about the way they run or respond to various changes.
No, I don't like to fight. Just misunderstanding what you said, that's all. You said excessively rich, not over-primed. There is a difference and I just didn't want the OP or any other user encountering the same or similar phenomena to think being (run) too rich will cause the problem this thread is about. As far as me having over-primed an engine and had the prop come loose? I honestly can't recall it happening on a 4-stroke yet, but I haven't been running these engines for that long. It could happen in the future though. I am certainly not immune to anything. I will say that I use an electric starter exclusively on my 4-stroke cycle engines and I use the choke on them too. I probably would encounter more priming problems if I ran them inverted, but I haven't done so yet. The OP's engine locking up certainly tells me it's being set too lean and is being run hot/overheated. Using a tachometer to set the needle would help greatly IMO. I always suggest to guys not familiar to 4-stroke cycle engines to open the main needle a half turn or more on a new to them engine before starting the engine to ensure its rich to begin with. Once the engine is running, I usually run up to WOT after a brief warm-up and open the needle rich further if it's running fast and clean until it slows down. Then I know it's rich and can start working it leaner. Using a tach, work the needle leaner giving a few seconds between adjustments to allow the engine to stabilize. As the engine runs faster and cleaner, the adjustments need to be in smaller increments until to noted drop in rpm, then richen back up a few hundred rpm.
If after an adjustment the rpm sags and the engine slows down, richen the needle quickly a few clicks. 4-strokes do not respond to needle adjustments as quickly as 2-strokes do, so the tell-tale sag doesn't happen immediately and if you go too lean too quickly, a backfire can happen and will indeed chuck a prop. A scary event for a new user as well as a seasoned user.
Dave - engines are engines.. Very true. They all run the same way although the adjustment procedure between various models can differ slightly. Some specific to Saito aren't my specialty, so I try to leave that stuff to the Saito experts.