Hey Everyone,
I was getting ready to put my 06 YZ125 away for the winter when I kicked it over and there was no compression. The only mods to the bike are a Pro Circuit pipe and silencer, V-Force reed and the head has been machined for race fuel(Klotz 108 octane mixed 40:1 with Klotz pre-mix). I ripped it down to find that the ring has seized in the groove on the exhaust side. The piston looked okay on top (blackish brown) and there are no abnormal marks on the cylinder wall. I have run this same set-up in my past three bikes with no problem. There is approx. 20 hours total on the engine(10h on a fresh top end).
I am at a loss. Any help????