Blue Line Valve Rocker Arm Assembly: 64mm 139QMB Type 1

Keep your 139QMB engine running smoothly with this OEM two-valve rocker arm assembly from Blue Line Designed specifically for Type 1 engines with 64mm valve stems and a shorter cylinder head, this is a direct-fit replacement that restores proper valve actuation and engine timing without modification.

Not sure which type you have? Type 1 engines have 64mm valve stems and a shorter head. If your valve stems measure 69mm with a taller cylinder head, you have a Type 2 engine (made by Zhejiang ZhongNeng / ZNEN) — this assembly will not fit Type 2 engines.

Key Features

• OEM Direct Fit: Exact replacement for Type 1 139QMB engines — no modification required.
• Complete Assembly: Includes rocker arm holder, inlet and outlet shafts, two rocker arms, two tappets, and two nuts.
• Precision Tolerances: Machined to OEM specifications for reliable valve timing and long service life.
• Broad Engine Compatibility: Fits all QMA/QMB engine codes with Type 1 head configuration.

Technical Specifications

• Rocker Arm Holder: L: 66mm / W: 66mm / H: 26mm / Holes: 7.4<9mm / Spacing: 50mm
• Shaft Inlet: L: 51.3mm / OD: 8.8<12.9mm / ID: M5
• Shaft Outlet: L: 43.5mm / OD: 10mm / ID: M5
• Rocker Arms (x2): L: 52.7mm / W: 22.2mm / H: 18.6mm
• Tappets (x2): L: 18.53mm / OD: M5x0.5mm
• Nuts (x2): L: 4.2mm / ID: M5x0.5mm / OD: 9mm

CSC Model Compatibility

139QMB Engine Code Compatibility

Fits 50cc and 80cc engines with the following engine codes (Type 1 head only):

Don't see your engine code? If it includes "QM" or "FM" and you're running a 139QMB Type 1 engine, this part is compatible.

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