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
Strange to see on a little 155cc....
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Re: Strange to see on a little 155cc....
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..Holds the exhaust valve open a bit longer.
Enables Piaggio to use a smaller start motor.
Re: Strange to see on a little 155cc....
At 6:47springer1 wrote: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..Holds the exhaust valve open a bit longer.
Enables Piaggio to use a smaller start motor.
Fish
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Re: Strange to see on a little 155cc....
Oh yeah . . . I see what you mean when he starts describing it at 6:40.See the mechanism on the side of the cam sprocket?
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Re: Strange to see on a little 155cc....
Wow, is that cool or what - I love learning about stuff like this.Old Grinner wrote:Oh yeah . . . I see what you mean when he starts describing it at 6:40.See the mechanism on the side of the cam sprocket?