yamaha 200 oil in crankcase 1985

hello i have got an 1985 yammy 200 when it sits<br />for a month or so the oil in the resovoir on the engine drains into the crankcase through the oil<br />injection ports i verified by removing the carbs and the oil pump and keeping the lines connected on the oil pump to see if it was from the shaft<br />but it is coming through the injection lines dripping very slowly, i also noticed it does not have or take the check valves like the newer motors, can you guys give me any suggestions on what could be causing this? is it the oil pump?<br />on the website (yammy) they only offer a kit to repair? i dont want to damage this motor and you can imagine fouled plugs!! landlocked for now<br />thanks

Re: yamaha 200 oil in crankcase 1985

The check valves are to keep the oil from draining down. I would have to suspect the oil pump itself. The kit includes the check valves and a new oil pump shaft to convert the old syatem to the newer pump. They rotate in opposite directions, so you have to install it all for it to work.