I was riding from Phoenix, AZ to St. Louis, MO and about 70miles outside of STL I was going up a hill with a head wind. When I gave it more throttle it felt like it was bogging down and then I felt a little pop. I guess that is how I would describe it. Then I loss some power and noticed in my mirror that I was blowing white smoke from my rear cylinder. When I got to the side my oil was showing about 220 degrees and I could hear the lifters real bad. I would say about like an old Detroit Diesel. I pulled the plug and it wasn't damaged but was caked in black carbon.

Has this happened to anyone on here? Is there something I should be looking for in particular before I tear her down?

EDIT: This was on my 98 XL1200 with 29,000 miles... Did the 1200 conversion 11,000 miles ago.

 

Are you sure the smoke was white or did it have a bluish tint to it?

 

Do a wet/dry compression test on both cylinders, that will tell a lot.

 

I went and got the compression tester. But the fittings it came with didn't fit my bike. It wouldn't have mattered though. I pulled off my rear head and found this.



I would say that explains the power loss and smoke. lol Could this be from a lean condition? or maybe a manufacturer defect in the piston? I'm guessing I should pull the front cylinder apart too... I'm fairly new to gasoline internals, I'm a diesel guy.

Any help or tips would be much appreciated.

 

Looks like there are some pretty good size chunks gone, I would think you would have to pull everything apart to look for those and make sure they haven't damaged anything else.

 

unfortunately, if the chunks went down it aint good. I would find every piece before turning the motor over again.

 

Damn sorry to see that.

 

Never seen such a clean piston for a carb bike with 11,000 miles on it ??

I'm thinking a lean condition causing detonation is the problem.

 

+1 Lean conditions will weaken the piston top and then you get what you see in the picture above....

 

I'm guessing I should pull the other head and see how the piston looks as well... or should I just replace both? If one runs lean they both should... correct?