I bought my '06 EC300 brand new and have ridden and raced it for 3 and a half years now. In my last race, I dropped the bike on the right side and when I picked it up and kicked it over, it was locked up. I thought I had siezed it. 
Long story short, the inner water pump shaft bearing had slid down when I dropped the bike and when I picked it up and tried to kick it over, the flywheel jammed it into the plastic gear. It looks like the bike came from the factory missing a 'C' clip to hold the bearing in place as there is a groove cut in the shaft for one. But looking at the parts diagram, this is not the case, it only shows one 'C' clip and it is holding the plastic drive gear up to the shoulder on the shaft.
Anyhow, since I have the engine half apart already, I decided that I might as well throw a new piston and rings in it. I'm sure the piston is starting to become fatigued and even though it still looks brand new, it's probably best to do it before it fails.
This leads me to the question about pistons. The rear of my jug is stamped with an 'A' and the on the top of the piston, there is an engraved 'B'. Is this normal? And does it matter what piston I put in if I'm not replating?
I also noticed one of the PV bearings had damaged dust covers on both sides. Not too impressed that the bike would come from the factory like that. It made the bearing have a sticky spot. AND, the PV actuator bracket stud (the little one that's welded in that the linkage attaches too) was sheared off. No wonder I fell over, I had no power to keep me upright.
Long story short, the inner water pump shaft bearing had slid down when I dropped the bike and when I picked it up and tried to kick it over, the flywheel jammed it into the plastic gear. It looks like the bike came from the factory missing a 'C' clip to hold the bearing in place as there is a groove cut in the shaft for one. But looking at the parts diagram, this is not the case, it only shows one 'C' clip and it is holding the plastic drive gear up to the shoulder on the shaft.
Anyhow, since I have the engine half apart already, I decided that I might as well throw a new piston and rings in it. I'm sure the piston is starting to become fatigued and even though it still looks brand new, it's probably best to do it before it fails.
This leads me to the question about pistons. The rear of my jug is stamped with an 'A' and the on the top of the piston, there is an engraved 'B'. Is this normal? And does it matter what piston I put in if I'm not replating?
I also noticed one of the PV bearings had damaged dust covers on both sides. Not too impressed that the bike would come from the factory like that. It made the bearing have a sticky spot. AND, the PV actuator bracket stud (the little one that's welded in that the linkage attaches too) was sheared off.
No wonder I fell over, I had no power to keep me upright.
