We have a 2005 CRF250R and we are losing transmission oil into the engine oil. The engine level increases until oil blows out the crank case vent (we have the crank case vent hose routed down the back of the engine case and not into the airbox to prevent fouling the bike upon wipe outs). We just replaced the counter weight shaft seal on the left side of the engine. We figured the engine was sucking transmission oil through this seal. But we still have the problem. We lose 500ml of oil in 20 minutes of hard riding. I'm afraid I need to split the case and go in deeper. It's quite obvious the oil is moving over as the engine oil becomes very dark and is obviously contaminated with transmisison oil. Any thoughs would be greatly appreciated??