anonymous.shyster wrote:
Do a quick check of your crank seals, filling the top cylinder with petrol to see if it flows out the bottom one is a quick and nasty way to see if it is not sealing between the cylinders. Of course, check for play in your crank while you are at it too!
After you've done this remember to stick some oil down through the crank...you've just washed away all the lubrication for the crank!