- Joined
- Jan 31, 2010
- Messages
- 3,026
You mentioned there was 12k miles on the bore. So I ASSUME the cylinders/pistons/rings were untouched during the head replacement. Is that correct? If so, did it smoke BEFORE you removed/replaced the head? If the answer is "no," was anything BUT the head changed? The tests indicate there are no issues with the head gasket or valves/seats but the seals remain a possibility and the fact that it doesn't start smoking until the engine has been running a while makes me AGAIN think about the rocker boxes being unable to drain oil as fast as it arrives. BUT...you said you checked and that's not happening.
I'm of the same opinion as Jim re stopping the oil flow to the head and I would be hesitant to do it. IMO, it seems to me you would have to wait at least 5-6 minutes and I think that's too long. Have you tried leaving the rocker cover off - yes it will be messy - and just observing the rocker box for drainage? I did extensive experiments on this some years back and, as noted the spindles facing the wrong way will definitely fill the boxes/submerge the valve guides/overwhelm the seals and it takes some minutes for that to occur. Of course, a plugged drain hole in the box will do the same thing. I know you said you checked all this but it fits the time frame and the smoking issue. Have you tried starting the bike, waiting for it to smoke, shutting it off, waiting for 4-5 minutes and starting it again to see if it smokes immediately or takes another 3 minutes to begin smoking?
Jim mentioned porosity and, if there was some porosity or crack between the rocker box area and the intake port, oil would, of course be pulled through when the engine was running. That would also take some time to occur from a start if the bike hadn't been running for a while.
How's the oil level in the tank? If too full, oil could be drawn into the air filter box/into the engine. BUT if that's the case, one would expect oil in both cylinders.
I'm of the same opinion as Jim re stopping the oil flow to the head and I would be hesitant to do it. IMO, it seems to me you would have to wait at least 5-6 minutes and I think that's too long. Have you tried leaving the rocker cover off - yes it will be messy - and just observing the rocker box for drainage? I did extensive experiments on this some years back and, as noted the spindles facing the wrong way will definitely fill the boxes/submerge the valve guides/overwhelm the seals and it takes some minutes for that to occur. Of course, a plugged drain hole in the box will do the same thing. I know you said you checked all this but it fits the time frame and the smoking issue. Have you tried starting the bike, waiting for it to smoke, shutting it off, waiting for 4-5 minutes and starting it again to see if it smokes immediately or takes another 3 minutes to begin smoking?
Jim mentioned porosity and, if there was some porosity or crack between the rocker box area and the intake port, oil would, of course be pulled through when the engine was running. That would also take some time to occur from a start if the bike hadn't been running for a while.
How's the oil level in the tank? If too full, oil could be drawn into the air filter box/into the engine. BUT if that's the case, one would expect oil in both cylinders.