OK, your shimming should be correct then, do you see anything around the button, like maybe fuel may be pushing through the threads and out the motor, also pull the carb and preasure test it, this only takes a min, check it by placing it under water, use a hair dryer to heat it some and submerge it in water and blow into the fuel line keep both the intake and exit of the carb covered when you do this, if the carb has a leak it will push bubbles out the alum HSN housing where it meets the composite body, or the rubber boot may have a tear or small pin hole in it, and don't be afraid to run the motor hotter than 220, once the motor loosens up the temps should have droped alot, so it can still be to rich with the settings your at know, and this can be a reason as well, but check the carb, and seal the backplate as well, you ewant to make the entire motor airtight. LMK what happens.