Its not only bad fuel that screwed that engine over. Look at the cranksahft. That engine must have eaten a LOT of dust...
Something i have found out this summer. I always used to run my engines compleatly out of fuel when finsished for the day. This sumer i forgot a few times and that enigne looks like new inside. No corrosion what so ever. So i took one of my worn out enignes looking good inside, and ran it on the street for a tank of fuel. Ran all the fuel out of it so if would not ignite anymore.
Well, engine ran totaly out of fuel, corroded inside and engine that i just stopped, and even had fuel in the fueltank, was like new inside. This was runnung Meccamo fuel. Avery very good fuel here in europe.
Running the fuel out of the engine also removes the lubricant out of the engine
Those internals look like an engine that had been mistreated fershur , lots and lots of
needle screwing which suggests either a very hard to tune fuel or a tuner having a tough time getting a proper mixture
Discoloration is not always a bad thing but with all these lil and also big companies that are producing fuel with one goal in mind , shear performance at expense of longevity to engine internals, its not hard to understand why engines are failing prematurely
Castor oil is important in a fuel blend meant for these little two stroke engines