this piece of crap. i have done EVERYTHING to remedy the 4 stroke issue. and the only thing that works is pulling out the air filter cartrage about 1/2 inch. the carb is clean, the airbox is void of any foreign objects. the filter itself is super clean. i can even take the foam filter out completely, but uless the cartrage is out 1/2'' it four strokes. here are some more possible causes i thought of while taking the pain in the ass apart...again. it says to use 25;1, that seems like a lot. i have been using 32;1. would more oil possibly displace the richness? what is the correct plug? i have an ngk bp6hs. there are no numbers on the main jet. could the previous owner possibly put in a bigger jet 20 years ago when it last ran? can you get different size jets?