Setting Valve Lash on a GY6 150cc
or 139QMB 50cc Chinese Scooter Engine
#gy6 #139qmb #scooter #moped
Setting Valve Lash on 139QMB and GY6 Engines.
Tools: 9mm Socket and/or Wrench
Needle nose Pliers or Tappet Wrench
Feeler Gauge/Gage between 002" and 005"
First Remove the Cooling Fan Shroud on the Right Side (Oil Sprout Side) of the Scooter.
Remove the Valve Cover on the Front of the Engine.
Turn the Flywheel till the Top Dead Center Mark lines up with the Indicator on the Crank Case.
You can easily confirm this when the Three holes on the Cam are showing and largest hole is centered vertically.
Loosen the Valve Lash Nut on the Intake and Exhaust Valves.
Select a Feeler Gauge/Gage to Three Thousanths of an Inch [0.003"]
Or to Four Thousanths of an Inch [0.004"]
Insert the Feeler Gauge between the Valve Lash Tappet and the Top of the Valve you are working on.
Adjust the Valve Lash till the Feeler Gauge is dragging slightly when you try to pull it away.
Re tighten and put everything back in place.
