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GY6 Valve Adjustment for 50 and 150cc Engines

  1. You must remove your valve cover
  2. The top valve is the intake and the one on the bottom is exhaust.
  3. Now you need to rotate the motor to get to TDC (Top Dead Center) The big hole should be at the top of the cam and there are two little holes with lines, the lines must be lined up with the case.
  4. Remove the spark plug.
  5. You need to pick up some feeler gauges.
  6. After you have it set up on TDC you need to check with a feeler gauge to see what the clearance is. I did look up what the valve clearance should be for the GY6 and found many answers. The best answer I found was to set both valves between .003" to .005". If you do not ride all that hard then set at .003", if you ride hard like most of us set between .004" or .005". I set mine to .005" and it is quite, not like before where the valve noise was louder than the engine.
  7. Now the real pain in the butt part. You need to loosen the nut that holds the valve adjuster.
  8. After you loosen it you can adjust the valve by using a Crescent Wrench to move the valve tighter or looser. You need to move a little at a time and keep checking the clearance with the feeler. Once you have the valve adjusted you need to hold the valve adjuster with the wrench while tightening the hold nut. This part is not easy as I kept on moving the adjuster just a tad and you need to do it over. So after everything is tight recheck the clearance before moving down to the exhaust.
  9. Once the intake valve is all adjusted correctly do it again for the exhaust valve.