Short Case GY6 QMB139 Scooter Engine 50cc, 80cc or 100cc

This is the 50cc short case scooter engine that fits scooters with short case engines.

You have the option of getting this engine in 50cc or 80cc or 100cc with the big bore racing engine.  This is the 4-Stroke complete engine, short crankcase.  For the 80cc big bore engine we install a 47mm cylinder and piston.  For the 100cc big bore engine we install the 50mm big bore cylinder and piston..

The 100cc Option 

This is the 100cc short case scooter engine that fits scooters with short case 50cc engines.

This is the 4-Stroke complete engine, short crankcase.  For the 100cc big bore engine we install the 50mm big bore cylinder and piston and a performance head in the engine.

The reason that your 50cc scooter engine is so weak and powerless is that your combustion chamber and piston is so small--only a little larger than a quarter.  see pictures below.  The power of your engine come from the explosions when the gasoline is ignited in the cylinder.  The smaller the chamber the small the explosion and the less power.  Compare to the 100cc big bore cylinder and piston kit you have double the volume of combustion chamber and thus far more power.  see pictures below.

• This is not the correct engine for Maddog style scooters, it will be too short and will not have the correct rear mounting point.
  
  
• No returns on engines.  Call us and make sure you are ordering the correct engine.