[LETMGROW]

I would be more inclined to think your issue is fuel or seal related rather than timing. If it was timing you should see evidence of overheating or melting on the other piston. I'd be checking carb boots and reed gaskets for signs of failure as well as crankcase seals.
Possible restricted main jet or needle out of position?

 

[LETMGROW]

Anytime I run across a melted piston(s) and I can't find an obvious reason for it I back up and take a close look at the fuel delivery system. I will drain the fuel tank completely and remove the fuel line and fuel filter from the fuel tank. The filter on the end of the pick up line is probably one of the most forgotten items in the whole fuel system! I change my filters periodically just as preventative maintenance. I have never found a satisfactory way to clean these filters. Another thing to check is the fuel line in the tank. These lines can rot away to the point where the filter can become detached from the line. This can present two problems.
# 1, the fuel drawn out of the tank will not be filtered.
# 2 the line may tend to float in the tank and when the fuel level becomes low the line may rise enough where it's drawing in air as well as fuel which will starve the carburetors of fuel. The filter acts as a weight to hold the line low in the tank. These pick up lines can crack over time too allowing air into the system. I will only use BRP Polyurethane lines part # 415005700 in my Mach 1 and Z sleds. Not over the counter gas line. I'm especially particular with our Pro Improved Mach 1 which gets fed VP C 14 fuel. It can be rough on fuel lines.
To be considered: The filters are small in size. Over a period of time these filters can become plugged and limit the amount of fuel which can be drawn through them.
Being hidden inside the tank these items are often forgotten or overlooked. When is the last time you checked yours?
I do my best to try using only filtered fuel. I have a funnel which has a fine mesh screen and a chamber under it which will catch any debris or water which might otherwise end up in my fuel tank. I don't use fuel additives. There is a warning on my funnel with the screen in it which states "additives may allow water to pass through the filter. If you are buying fuel on the trail this isn't practical. You can only hope the tanks owner keeps a vigilant eye on filters etc. to pump only clean fuel. Most of these tanks sit outdoors in all kinds of weather. Hot, cold and everything in between. I'm sure they don't get "Dip" tested like the tanks at a filling station with a long stick with a test compound on the stick.
One other side note about buying fuel "On the trail". You never know what you are getting. A few years back I was riding with my family and we stopped at a popular place for a burger and a drink. This was in the middle of the week and my kids were on winter break from school. I watched as a fuel truck pulled up to the gasoline storage tanks. There were two tanks. One for regular gasoline and the other for premium gasoline. The tanker driver filled the regular gasoline tank then stepped over and began to fill the premium tank. He didn't touch any valves or anything else on the truck. This told me anyone paying for premium gasoline was getting the same gasoline I was when I was filling up the sleds with regular. Anyone buying premium was only paying a premium price for regular grade gasoline.

 

[LETMGROW]

Makes me wonder what was in his burger!

They used to have horses.

 

[LETMGROW]

Did you know that before you ordered?

The Army had worse.

 

[LETMGROW]

Do you have a picture of the cylinder head? Mainly the combustion chambers.

 

[LETMGROW]

My first exposure to two stroke engines was in 1962 when I went to work in a Saab dealership. The Saab 93 GT with Abarth exhaust, three carburetors and the 4 speed transaxle with the shifter on the column was the hot set up.
The Saab cars had a free wheeling feature which meant when you let off the gas pedal the engine slowed to an idle. This was so the engine wasn't turning high RPM's with very little fuel going into the engine which would limit the oil for lubrication.
The dealership owner raced on the ice track at Watkins Glen Raceway. I was his pit crew. Good times. The owner attended a race school in England where he met former world champion Sir Sterling Moss. I had the opportunity to meet Sterling Moss when he was in the US for a tour and he came to visit the Saab dealership's owner.

 

[LETMGROW]

I'm not worried about low RPM.

I want to protect at higher RPM / load - I think.

High RPM was no problem. You dumped a quart of Saab 2 cycle oil in the gas tank then added 8 gallons of gas. 32:1 gas to oil ratio.
Smokey little devils. We rebuilt / replaced a few engines because someone would fill the gas tank and forget the oil.