Polini221 vibrates heavily above 7k rpm

[Svint1]

Hi!

I have a Polini221 engine that rides very smooth. -never had so little vibrations in a Vespa engine...

But that is only as long I don't push it over 7000rpm...

-then it starts to vibrate heavily...

I'm suspecting that the pick-up isn't all good, and can't deliver proper sparks above 7k rpm.

-does that makes sence?

 

 

Setup;

PX200 casing matched to sylinder

60mm crank (unknown brand, bought here on GSF)

SI24/24 autolube with nd3,33 and hd128

Standard ignition on 19"

Polini box exhaust.

 

 

Rgrds
Ø

Bearbeitet 7. Juni 2019 von Svint1

[Crank-Hank]

Put in a bigger HD

Carb is overworked?

[Svint1]

Put in a bigger HD
Carb is overworked?

Tried 135, and same vibrations...


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[shamane]

Are the vibrations gone if you come in higher revs?

[Svint1]

Are the vibrations gone if you come in higher revs?

Haven’t tried to push it to far above 7k, as it vinrates so much.


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[shamane]

I think it comes from the Polini Box. I had this, too. With an other Polini Box the vibrations were gone.

[Svint1]

1 hour ago, shamane said:

I think it comes from the Polini Box. I had this, too. With an other Polini Box the vibrations were gone.

Ok, thanks!

 

Very usefull information!

-I have been thinking of that myself, but wasn't sure...

I might try with a SIP Road to check....

[Dudenhofenssohn]

I ve tested the Polini Box since 600km with a bunch of carb. Modifikations but I still have these vibrations. 

 

There could be a relation between the attachment oft the Box and the cylinder, i guess.  I´ll try to put on the viton attachment, to solve this Problem.