CM91 white smoke from cylinder head

Discussion in 'General' started by jeff kjoller, Jun 30, 2019.

  1. jeff kjoller

    jeff kjoller New Member

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    So I finally have my CM91 starting on first kick. No more leaks from the carb. Everything is adjusted and it is running smoothly. BUT, after it runs for a minute or so, white smoke starts coming out near the cylinder head. I can't find exactly where but its wisps of white smoke like you would see coming from a cigarette burning.
    Is the gasket going bad?
     
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  3. kirrbby

    kirrbby Well-Known Member

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    If the smoke is puffing out with every stroke of the piston, you have a problem. But if it's just oil or something burning off of the outside of the exhaust, cylinder, or head...it should stop after it all burns off. If it persists, you have a problem.
     
  4. jeff kjoller

    jeff kjoller New Member

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    you can sort of see the smoke in this you tube video. It's faint but there towards the right side of the cylinder head. You will need to enlarge the viewer to see it.

     
  5. racerx

    racerx Administrator
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    Very hard to see. As best I can tell, it looks like it's coming from the main oil passage...getting past the sealing washer & acorn nut. That's unusual. Check the crankcase breather. It could be the result of excessive crankcase pressure. Also, if the pressure leak is coming from the stud passage, you'll get an oil leak, too. Don't bet the farm on this, it's just an educated guess based on very little visual evidence...better than nothing and that's about it, for now.
     

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