Strange engine running problem please help

I'll throw out a couple things to check, Is the carb flooding? Is there still a good seal on the cylinder and the head? How much oil do you put in your gas? See if the magnet is still strong, you might need a new one. I have one lightly used laying around for you if you do...

Change that spark plug brother! Two strokes are known for fouling plugs and sometimes cleaning a plug doesn't help! it may be that simple!

Re: strange problem please help

I would check the torque on the head and check the exhaust for a restriction, it could also be the spark plug. Just because a plug looks good doesn't mean it will work correctly.

kinda sounds like a leak clean it well then look for oil around case seams, head seat, and spark plug. Also check the crank seals. When looking at the case seams, you're only looking for the least stain of oil in a blotch along the seam.

Good advice above... check everything mentioned above and also run a compression check if all else is good and you're still losing power. Compression readings are fairly low on a stock engine already so if you lose any compression it can cause a very noticeable power loss. Stock compression is only like about 90 psi so you get the idea.

The good thing tho is if it did lose compression it only costs about $35 to $40 to replace the jug, piston, and ring and restore power. i get mine from BoyGoesFast on ebay as a complete set for $25 plus shipping so it comes out to $35 or so for a new cylinder, piston, and set of rings.

What causes premature compression loss is the plating on the cylinder walls can chip and peel off around the ports since these areas are rather sloppy from the factory and should be cleaned up before running. If you look at a new cylinder you can usually see or feel some of the plating where it overlaps into the port areas and this should be filed off and slightly chamfered for best longevity. If it is left in there and not taken care of it can start to peel from where it overlaps or it can even cause a ring snag or a scratch in the cylinder wall which would cause enough of a compression loss to cause your power loss.
Another thing you can check if you don't have a compression tester yet is to remove the head and rotate the crank so the piston is at the bottom and check for scratches in the cylinder wall, these will kill power.

do you still have the fuel filter INSIDE the fuel tank that most of these tanks come with?? might remove the petcock and check to see fi thats clogged.

i guess before doing that, just see if you get good fuel flow into a bottle from the fuel line that goes to the carb. remvoe it and turn the petcock on and see what ya get.