seen this loads of times mate(being a bike dcotor)usually its a yamaha that has this problem.the rubber veins in the oil pump are worn and the oil is leaking through it with gravity.the best thing to do is take the carb and inlet manifold off and then the reed block and take the plug out.then pour about half a cup of fresh fuel into the crankcase where the reed block was then put the reed block back on and inlet manifold back on then the carb, shake the bike about a bit with thr front brake on and give it about 10 really fast kicks with the throttle right open it will spew the fuel out of the plug hole and wash the oil out of the crankcase.then refit the plug and turn the ignition on open the throttle right up and kick it hard again make sure its on the centre stand it will start and smoke alot just keep the revs up until its cleared the excessive smoke.but do change the oil pump if you are going to not use it to often as it will do it again.if you use it pretty much everyday it may be ok.
adam bike dcotor, March 2010
