Damage to engine at WOT?

Under a sufficient load, nothing.

there is another thread about this on here and it just turned into a battle i tried searching for it but could not find it i thought it was called "how long can you hold it to the pin"

you remember what I'm talking about JOE

If it breaks, you had under lying issues you did not know about. Fresh engine will last 30 minutes plus 2 laps, Okie said so!

Even a perfect engine with perfect jetting will eventually crater, so, if you want to get technical -- and in these type of arguments, that's the only way you ever win -- your friend is wrong. Nothing lasts forever, or even "as long as you want."

Compared to a four stroke a two stroke can survice a much higher RPM.

There are consequences to the higher RPM, however.

As the RPM goes up the forces that the engine is subjected to goes up. Some forces will double if you double the RPM, some forces will go up four times if you double the RPM.

At higher RPMs the balance of the crankshaft becomes a factor. Any imbalance puts a load on the crankshaft bearings. As a minimum the wear and tear on the bearings goes up and at the worst the load can become so great that the crankshaft can break or the case where the bearings are held can fail.

The connecting rod is a far more likely source of failure as it is subjected to tremendous forces. If you let the RPMs increase without limit the most likely failure would be the connecting rod breaking, which in turn would hammer the engine into little pieces.

High RPMs plus wide open throttle equals maximum power, which in turn equals maximum heat being generated. If there is any issue at all with the octane of the gas, the quality of the oil or the ability of the cooling system to remove the heat this is where it will show up. If the connecting rod didn't break first then I would expect the piston to melt after a prolonged period of operation like this.

I would certainly not agree that you can operate at WOT as long as you want, unless yo only want it for short periods. The straight away of a typical track, no problem. A few minutes down a sand wash would be okay. Pull onto a paved road and sprint for 20 miles...... expect a blown engine.

Rod

4-stroke gas engines burn/tulip valves if run continuously at a high power output. 2-stroke gas engines don't have valves, but they don't cool their pistons very well because they have a power stroke every revolution, don't have oil cooling of the underside of the piston, and generally have fewer piston rings (not necessarily true with the current generation of 1 compression ring 4-strokes). An agressively turned 2-stroke is likely to burn a piston in short order if you run it at full power for an extended period of time.