My bike is a 96 250 I have had it since new it has about 40,000 miles on it. The engine started to develop a pinging noise that I had determined was detonation in the left cylinder. I disassembled the engine serviced the valves, replaced the rings and honed the cylinders. A new gasket kit was installed with new valve seals. I assembled the engine and every thing looked perfect and it started up smartly on the first crank. I ran it easy for the first few miles and then increased the power, soon after within 200 - 300 miles the left cylinder started to smoke heavily and evidence of detonation returned. The right cylinder was clean with no smoke. I disassembled the engine the second time and the left cylinder valves are heavily caked with carbon, the piston has no carbon on it and is very clean. The rings are new and in pristine condition, the valve seals are new and still in good condition and there is no slop in the valve guides. Even if the valve guides were faulty they still wouldn't convey the amount of oil that it is consuming. The entire lane behind me is a cloud of blue smoke. At this time I can see nothing out of the ordinary. I am going to return it to my tech and see if he can diagnose the issue. The only thing I can think of that would cause this amount of oil consumption on one cylinder would be a crack some where, hopefully not. I will report later what the tech has to say.