Re: My 2 stroke is 4 stroking..
I discovered on teardown of one of my BGF motors that the seals are junk. They were flaking and looked used. I went to a bearing house and picked up some high quality seals and cured my problem. Most metric seals have the sizes molded right into them, like 14.8 27 5, and 14.8 27 7. My crank shaft measured 15mm, so the seals I ordered were TCM #15X27X5TC, and TCM #15X27X7TC. Metric seals use the bore, o.d., and thickness as the part number.