Strange to see on a little 155cc....

[fish]

See the mechanism on the side of the cam sprocket?
That lowers the compression during starts on this Piaggio "Liberty 150i 3V i-get" engine. Holds the exhaust valve open a bit longer.
Enables Piaggio to use a smaller start motor. (and probably helps the measly 6Ah battery!)



I had to go to Vespa's Robot to find if my guess was correct.

Fish

[springer1]

Holds the exhaust valve open a bit longer.
Enables Piaggio to use a smaller start motor.

I'm thinking it isn't a compression release like my old BSA single had .... rather a variable valve timing gizmo, like any newer cat or truck has. That looks like it's centrifugally driven, the same as the older vintage points plate in the distributor would be shifted by weights & return springs to alter ignition timing..

[fish]

Holds the exhaust valve open a bit longer.
Enables Piaggio to use a smaller start motor.

I'm thinking it isn't a compression release like my old BSA single had .... rather a variable valve timing gizmo, like any newer cat or truck has. That looks like it's centrifugally driven, the same as the older vintage points plate in the distributor would be shifted by weights & return springs to alter ignition timing..

At 6:47


Fish

[Old Grinner]

See the mechanism on the side of the cam sprocket?

Oh yeah . . . I see what you mean when he starts describing it at 6:40.

[springer1]

See the mechanism on the side of the cam sprocket?

Oh yeah . . . I see what you mean when he starts describing it at 6:40.

Wow, is that cool or what - I love learning about stuff like this.