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Story so far: My 1976 CB200 with under 1700 actual miles is smoking when hot from left cylinder (white ish smoke). Not choking clouds, but enough to feel pretty bad sitting next to a Prius in LA traffic... I've gone the Mystery Oil route, no dice. The left cylinder did have a lot of carbon build up when I got it, not sure if that helps. I checked the compression and got 120 psi from both cylinders. A mechanic at a local shop suggested lightly misting water into the open air intakes, he said, if done carefully, the water would pretty much steam clean the internals. He cautioned against putting too much mist in the intakes, saying that it would cause hydro-lock, not sure what that is, but just like a low-flow-shower head, I don't like the sound of that... I ask the wise ones in this forum, what is my next step, is the steam bath a good idea? Re-ring, Valve guides? I appreciate all suggestions, your help is instrumental in my enjoying my bike and motorcycling in general, thanks in advance... -ryan-
 

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120 is good compression - Pull your plugs and do a reading. I'm not sure about the water treatment - sounds a little odd to me. I would not just change a ring or a valve, if your planning to tear the engine down - I'd do it all for both cylinders. If the mc is running pretty good, I'd run it until your ready to re-do the engine, just make sure you can source all the parts first.

Other than worrying about your carbon foot print, enjoy the ride.
 

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the water trick is an old hot rodders trick to decarbon the inside of an engine. Used to work on old muscle cars, never tried it on a bike. Hydrolock occurs when you have too much fluid in the cylinder. As you know fluids don't compress so if you have too much water in a cylinder it will have the same effect as the piston hitting the head itself.

check your jetting and do a leak down. leak down will tell if if you rings are bad, but I suspect if you are seeing white smoke the bike might be running lean.

Keep in mind, bikes lean to the left on the side stand, you might have a valve seal leak that is allowing oil to drain into the cylinder when parked and burn when you start it up. Once you get oil in the pipe that sucker burns for days.
 

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btw, is your buddy who told you about misting the water a buick guy? the guy who showed me that old trick was an old timer mechanic at a buick dealership and it seems to me all the guys I ever hear mention the water trick own old buicks.
 
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