Hello, My name is Pablo, I'm from Chile and this is my first 4 stroke, I bought this bike from a guy who bend 4 valves after a full rebuild, but he didn't replace the timing chain, damper and tensioner. I took it home and bought springs, valves seals and took the head to a shop so I would just install it and set timing. The cylinder looked OK, not great but useable(iron sleeve, plating doesn't exist down here, all the bikes run steel and do OK), the piston and rings had just a few hours, and the rod too, the bike was running great until the chain slapped. When I installed everything(with the ring end gaps where they belong), second kick and it ran good, but the blue smoke just didn't stop, it was like the bike was on fire. Did a test run and damn it pulls, nothing compared like the cr250r I previously had. The compression is great I can't get pass the compression stroke without the decomp lever(I'm 240lb), but the oil out the exhaust kept going, so I decided to take everything apart and start all over again. With the help from a friend we re installed the cylinder and found out that the piston pushes oil trough the rings up to the combustion chamber in every stroke, like the oil was under pressure, even after when we drained almost all of the oil out of the engine. This was done by pushing the kickstart lever with only the cylinder installed, is this normal?. After all of this we honed the cylinder because it seemed glazed and re installed everything hoping that the rings would settle this time. First couple of kicks and it ran ok but died after a few seconds, then again holding the throttle and started to rev it up over some dunes, when I was getting back to the truck I noticed water everywhere, the head gasket was leaking and the base gasket was literally blown away from it's place by all of the compression that the crankcase is holding. The oil level wasn't even at mid. What the hell is wrong with my YZ? Please help!