Huasheng burnt valve(s)?

Discussion in '4-Stroke Engines' started by unior, Aug 19, 2010.

  1. unior

    unior Member

    My huasheng recently started popping and backfiring. I adjusted the valves and the problem went away temporarily. Now its starting to pop and backfire again under heavy loads and lower rpms. Could I have burned a valve? Do I have to split the entire motor to get them out?
     

  2. unior

    unior Member

    found valves for eight bucks i wonder how hard they are to install
     
  3. unior

    unior Member

    Well I tore her down, removed, cleaned and reinstalled the valves to no avail. The engine makes no power and backfires. She's about done for I worry. I guess the seats are scored or messed up?

    BTW HS valve removal = remove clutch, remove flywheel, removed front cover, disconnect connecting rod bolts and push piston up in bore away from crank, remove crank, remove piston, remove valves.
     
  4. GearNut

    GearNut Active Member

    Burnt/ pitted valve seats will cause what you are experiencing as well as severely reduce the compression. Have you done a compression test? I have no idea what the compression should be on your engine but anything less than 100 psi is very low.
    Are you positive that the ignition is firing properly/ correctly timed?
     
  5. unior

    unior Member

    I visually inspected the seats but they are tough to see way down in the engine. I dunno maybe ill try lapping them.
     
  6. Old Bob

    Old Bob Member

    backfiring is usually an ignition timing or misfire problem, as indicate under heavy load or low rpm I would change plug, its common for bad plugs to misfire under load.
     
  7. unior

    unior Member

    Ok so now my huasheng is out of time. I realized upon removing the crankshaft the cam gear moved outta time. But I can't find any timing marks on this gear.
     
  8. GearNut

    GearNut Active Member

    Well, that's alot easier than repairing a burnt valve seat.
    There has to be timing marks on it somewhere.
    One tooth shorter width wise on the gear?
    A little dot?
    A short line?
    I have even seen the mark being just a v notch in the tip of a gear tooth.
    That was a PITA to figure out.
     
  9. unior

    unior Member

    found the timing mark on the backside of the plastic cam gear. too bad it's half destroyed...pics to come...
     
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