I just bought a 92 B400 with only 2500 miles on it. It's in Mint Condish...Problem is 2 cylinders have 125 lbs of compression, the other two have 100 and 75 lbs. The bike was in the dead zone for years at teh shop, I offered the guy cash and he took it. My plan of attack is to Drain gas, clean carbs, new oil, charge battery and get her to at least start, after that, I shall devise a diagnosis. I have a laundry list of things that were done to the bike while it was in the shop. It seems that they have given up on it though. New valves, springs, gaskets, plugs, wires. It's a machine right, the problem is somewhere. Could a bad crank seal be the problem. i'm picking the bike up thursday, and starting work immediately. Any suggestions would be appreciated. Thanks