Chinese 4 stroke GY6 50cc with 100cc BBK. Can't exceed 35MPH
by: deejae - May 20, 2018 15:01:46 GMT -5
Post by deejae on May 20, 2018 15:01:46 GMT -5
I did all my mods the sames weekend. In regards to specs for the bbk I only have the info that I posted above from the manufacturers website. Yes I am using a 100 main jet on my new carb.
Here is a cut and paste from the manufacturers website showing the specs on the bbk I installed
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Performance Cylinder Kit Chinese Based Scooters
Boost your 50cc from a 39mm Bore to a 50mm Bore,
This is one of the biggest kits on the market
4 stroke 50mm cylinder set. Kit includes cylinder, Performance Head with Valve Set, Rocker arms, Piston, rings, Piston pin, cir clips, A9 cam, head gasket, and base gasket.
Specification:
Cylinder Bore: 50mm
Wrist Pin Diameter: 13mm
Total Piston Height: 34.8mm
Compression Height: 18.3mm
Valve Length: 64mm
Rocker Arm: 64mm
In regards to limitations I removed so far;
I replace a carb with the screw heads cut off (prevented port access).
I replaced an intake insulator gasket which had a restricted ID of 14.5 mm and is now 19mm.
I removed a spacer/limiter from the variator. (Prevented stock variator from closing enough to push belt to end of pulley)
I replaced stock CDI with blue performance racing CDI.
I removed stock throttle grip which wouldn't allow full twist of stock throttle.
I removed air box and replace with exposed bug screen covered performance air filter.
I removed PAIR system.
I replace Chinese no name 100/60/10 tire with Pirelli 100/9 0 /10 tire.
I replaced stock restricted exhaust with wide open performance exhaust.
I replaced stock reduction gear from 51/15 to 47/17.
I replaced fuel valve and fuel filter (just incase - not sure there was any restrictions there)
BBK didn't have a port for PAIR so I replaced valve cover to a non PAIR cover.
I replaced the spark plug and cable.
I replaced the stock clutch assembly with a racing clutch with 2000 rpm clutch springs and 1500 rpm torque spring
I replaced the variator and weights.
I replaced the variator drive face gear... required changing the bendix and starter as well.
I replaced 4ma battery with 7.5ma battery.
I replaced the stock rotor with a performance rotor and pads from EBC (FYI - EBC part # FA-151 fits Chinese stock caliper.)
Here is a cut and paste from the manufacturers website showing the specs on the bbk I installed
----
Performance Cylinder Kit Chinese Based Scooters
Boost your 50cc from a 39mm Bore to a 50mm Bore,
This is one of the biggest kits on the market
4 stroke 50mm cylinder set. Kit includes cylinder, Performance Head with Valve Set, Rocker arms, Piston, rings, Piston pin, cir clips, A9 cam, head gasket, and base gasket.
Specification:
Cylinder Bore: 50mm
Wrist Pin Diameter: 13mm
Total Piston Height: 34.8mm
Compression Height: 18.3mm
Valve Length: 64mm
Rocker Arm: 64mm
In regards to limitations I removed so far;
I replace a carb with the screw heads cut off (prevented port access).
I replaced an intake insulator gasket which had a restricted ID of 14.5 mm and is now 19mm.
I removed a spacer/limiter from the variator. (Prevented stock variator from closing enough to push belt to end of pulley)
I replaced stock CDI with blue performance racing CDI.
I removed stock throttle grip which wouldn't allow full twist of stock throttle.
I removed air box and replace with exposed bug screen covered performance air filter.
I removed PAIR system.
I replace Chinese no name 100/60/10 tire with Pirelli 100/9 0 /10 tire.
I replaced stock restricted exhaust with wide open performance exhaust.
I replaced stock reduction gear from 51/15 to 47/17.
I replaced fuel valve and fuel filter (just incase - not sure there was any restrictions there)
BBK didn't have a port for PAIR so I replaced valve cover to a non PAIR cover.
I replaced the spark plug and cable.
I replaced the stock clutch assembly with a racing clutch with 2000 rpm clutch springs and 1500 rpm torque spring
I replaced the variator and weights.
I replaced the variator drive face gear... required changing the bendix and starter as well.
I replaced 4ma battery with 7.5ma battery.
I replaced the stock rotor with a performance rotor and pads from EBC (FYI - EBC part # FA-151 fits Chinese stock caliper.)
