what do your spark plugs look like? I had a similar problem on my xr2 and it was the little check valves that screw into the reed block that drain fuel back to the cylinders were stuck open. they have black spaghetti rubber lines going to them. I had 2 that were bad, and it really made my motor load up on fuel, and foul the plugs. I repplaced the bad ones, did a decarb with engine tuner in the spray can and put new plugs in and its doing much better. Im also switching from the blue jug wallart 2 cycle oil, to some pennzoil synthetic blend, and reducing the mix ratio to 60 to 1, since I primarily idle around or cruise at midrange .
you can test the little check valves by blowing in them they shouls seal in one direction, and free flow the other way. they have little plastic balls in them that act as check balls, that get out of round. So check them several times before you call them good, because if the liitle ball spins a liitle, it will seat, then then next time it might not.
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