Bogging, lean, now rich?

[catchacuda]

Looking for some advice here.
Dinli atv with 1e40qmb
Ran fine all day. THEN,topped off the gas tank with the usual 40:1 premix. It ran for about 40 seconds and began stumbling with any throttle input. I pulled the plug and it was dry and obviously was seeing a lean mixture. Noticed the head and cyl seemed very hot after such a short run time. I then put a new plug in it, and its running again but was ideling poorly, wanting to stall. I had to turn the mixture screw nearly all the way out to get a decent idle. (Carb is the typical slide type like in GTVert's carb videos)

Any input of where to start? Im lost because the first issue conflicts with the second I beleive. After the initial hiccups, I let it cool and it behaved well for a very quick test ride.

The carb was cleaned about a week ago, the fuel cap does indeed vent, running a manual shutoff, and 1/4" hoses.

My first thought is to check the fuel hoses for signs of deterioration, and once again tear down and clean the carb...

Long winded yes, trying my best to explain the situation.

[90GTVert]

I don't know that you can accurately judge if the engine is running a little hot just by observing head temp without a gauge. Even running normal, they should be pretty darn hot.

Was the plug color looking lean (white or light) or just a dry plug after trying to start?

Was the fuel source/batch the same one used previously? If not, especially if there's still a loss of performance, possibly a gas issue.

Some rubber hoses can have bits and pieces come off and clog things. A clear fuel filter lets you know if that's potentially an issue at a glance or translucent tygon hose can be used and that doesn't flake off. It will harden and lose flexibility over time though.

[catchacuda]

Thank you for the reply!
The plug was well used, and when pulled was nearly white and dry. Right, without a temp sensor im probably just being paranoid. The gas we mixed with was also fueling a 150 gy6 with no issue. On a side note I pulled the carb, found it's vent hose was MIA and a bunch of dirt was clogging the vent's barb. Could something so simple be the culprit? As of now it seems to running fine.

[90GTVert]

That could be it. It needs to vent to atmospheric pressure for the carb to function properly.