thanks sleeper idk the compression seems fine when u put ur finger over the plug holes it will plow your finger off an make a pop idk if its a 4 mill or not how can i tell? i went riding for a few hours today on it an it just seems like its spitting an sputtering at wot an when it reves bak down seems like it wants to load up an bog out an sometimes when u wind it out in first an hit second it just falls on its face everything is tight an nothing is sucking air or leaking any other thoughts?? thanks alot