- Nov 23, 2003
I have had my 02 yz125 ported and polished and i was out riding it the other day and i noticed sthis strang sound. When the bike it in like 4th or 5th gear about midway through the rev it makes a noice like somthing if flapping but then it goes away as you get to hig RPM. i have torn the top end apart nothing took the reed valve apart still nothing and i checked all the bolts and nothing is loose. What the heck is this "flapping" noise i hear. There is no power lose or n e thing soo i dont know.