What a thread....
This was not just a long thread, but a interesting one. There are a couple steps you can take to make sure your systems are in good shape, in this case, the oiling system.
I totally agree with Dr. Honda. The only engine I have ever premixed was my outboards, which called for premixing.
Premixing these engines, especially if your still using the injection system, can cause carbonizing. This can be just as bad as not running enough oil.
The biggest tell tale that your oil system is not working well is the spark plugs. Because I also own this boat, along with the 1997 GTX with the same engine, I carry tools with me and check my plugs real often. Yeah, I'm there to enjoy my day on the river but the way these motors are set up, it takes 3 minutes of my time to get satisfaction that my motor is performing well.
The oil injection system is more reliable than most other parts of your motor. There are 5 types of pumps used today, that I know of. Since school, they might have come out with more, but your oil pump is a simple "gear" type pump. It's directly geared to the crank shaft via the magneto and uses one drive gear. Most gear pumps use a power gear and an idle gear. The lubrication is from the oil that passes through the pump itself, on it's way to your injectors. This pump doesn't usually just go bad, it breaks. As long as your filter is keeping out grit, the pump should last forever. You can feel the pump during operation to see how warm it is. It should be warm, but not so hot you can't touch it.
To see that it's running correctly, you can also grab the cam and wind it wide open while at idle. The motor will begin to smoke like a mosquito truck. If you get that kind of smoke, the pump works fine.
Myself, when I have an engine down, I take the gear pump (oil) and connect it to my drill. I made a special piece that I connect to my drill, run in the counter rotating direction and watch it pump oil. It's a very reliable way to ensure you have a positive flow through the pump. The drill is not exactly a high rpm motor, so you won’t see it blowing out a stream of oil, but it will flow oil.
Looking at your pictures, it doesn’t look like a lack of oil caused the destruction of the piston. If you look closely, you’ll see the carbon and oil residue on the pistons and heads.
From just a first hand thought, I think you lost your piston to a bad crank bearing. It’s possible that you ingested something or one of the rollers flat spotted.
The spark plugs, which you don’t show, would have also showed us if it were due to a lack of oil. Back in 2007, this was one of the first engines I worked with, helping the previous owner (Kustomkarl). He asked many questions about the issues he was having and we worked together to solve his problems. I’m pretty sure he bought new parts to replace parts that were bad. But, if there was a flat spotted bearing, there would be no way he’d have known this.
If you have an engine stethoscope, you can listen to the bearings and with the trained ear, know when you have one that isn’t up to par. There is a rat-tat-tat kinda sound coming from the bearing. Roller bearings are easier to determine a problem with more-so than the 4 stroke journal bearings. With babbitted bearings, there isn’t a lot of leeway on determining a problem exists. You can hear the rattle of your crank on startup or you might notice a loss of oil pressure.
Test what you can, be vigilant in reading the spark plugs and take compression readings every so often and enjoy the season. Don’t be gun shy. Using premix when you know your injection system works is a waste of money and won’t stop you from blowing an engine. Running double oil will cause carbonizing and fouling plugs. It won’t protect you from blowing a motor……..
:cheers:
