4 stroke engines

[MotorBicycleRacing]

looks like AGK is using something like this to get 2 speeds
its not a new idea was used on rupp minibikes in 1968

 

[Ibedayank]

like I say its not a new idea

 

[Fuzzy79]

Trying to not sound like a complete noob, but how does that system change gears I see no shifter or linkage to change the gears, especially on the pic of the pup

 

[Ibedayank]

The clutch on the engine simply has two sprockets on it. theres no direct drive off the engine. One chain goes to the one way clutch and the other goes to the clutch on the jackshaft. the one way clutch is first gear. the clutch on the jackshaft is second gear which has its sprocket on the weight side and the bell is solid on the shaft. when the speed gets high enough on the jackshaft the weights solid up second gear which frespins 1st and off you go.