Polini twin induction crankshaft question

[Ospite]

First of all I appologise for my lack of language apart from English.

 

I'm currantley looking at building a Polini motor from an old kit I've had stored for sometime,on inspection it turns out to be the TI version.As a proud Scotsman I hate waste and feel the need to utilise whatever I've got.

 

I realise that the Polini manifold is a reed valve item so going by this I presume I will need to run a suitable crankshaft.

 

After a browse around SIP I've come up with a couple of alternatives but I'm unsure as to which is the more suitable for this application,the Mazz full circle or the Worb5 special lip version.

 

-Worb5

 

 

 

All help will be gratefully received,thank you gentlemen.

[Ospite]

The twin induction cilinder can't run with the full circle crankshaft because the specific manifold for twin induction has the reed valve only at the side of the cilinder and at the other hole the flow is regulated by the rotary valve , therefore you can fit a standard crankshaft or a Mazzucchelli with a "standard cut" BYE

[+ curare]

hello,

 

to say a little more:

 

no special lip. As vespazizzo wrote still needed the rotary induction and special lip crank doesn't seal the compression plate.

 

Don't buy a race crank with double intake.

With double intake better the standard crank. It is question of inlet time and since of its design with double intake your inlet time is already much longer.

[Ospite]

Ciao Curare, se lo special lip è quello della prima foto come ha fatto capire Juan, ha solo la spalla che non fa da tenuta smussata, l'altro lato sembra normale...e comunque se il cilindro è tirato e non lo usi tutti i giorni si può azzardare a montare anche un'albero anticipato

[+ ArtLab Garage Italy]

La spalla smussata è proprio quella che fa da tenuta, quest'albero è indicato per il montaggio di un collettore lamellare al carter in quanto la spalla lavorata in quel modo favorisce l'ingresso della miscela. Ciao

[Ospite]

La spalla smussata è proprio quella che fa da tenuta, quest'albero è indicato per il montaggio di un collettore lamellare al carter in quanto la spalla lavorata in quel modo favorisce l'ingresso della miscela. Ciao

 

quoto!!

[Ospite]

Ooops non avevo guardato da che parte è il cono del volano...in effetti è proprio la spalla che fa da tenuta ad essere smussata allora modifico la risposta a Juan di sopra...

[+ CRISTINE]

l albero a spalle piene converrebbe montarlo su un aspirato al cilindro..

e l altro su qualsiasi aspirato lamellare anche al cilindro..

[Ospite]

Thank you gentlemen.This is the first time I have experianced the TI so I'm even happier that the standard crank is used as it saves me more money.

 

Thank you for your help.Curare,I would have asked over on SIP but it seems you don't look down on the smallframe forum.If it's not too much trouble do you mind if I ask for advice when I build a Polini 50 motor for my daughter?

 

Thank you again.

[Ospite tecnofalc]

your welcome Kerr..I say, in alternative take the full circle crank and cut where the crank side control the inlet in case...you will decide the complete phase, cranck + valve...I think about 185/190° are enought for a wrong TI polini..

 

this is an old modified do many years ago to Parma land...land of many good vespa tuner people...

 

but wich tipe of exhaust pipe you will mount on your TI?

 

ciao

[Ospite]

ahi ahi... io non so una virgola d'inglese...

[+ Whine]

Mazzucchelli also products a crank with special cut appositely made for the 130 polini with double intake: it has an inlet time longer than the original crank but shorter than a common race crank.

The fact is that with a common race crank you have a negative interference between the rotary valve and the reed on cilinder.

[Ospite]

Thanks gents,more food for thought.

 

I think I may as well just split and cut an ETS crank for this motor by the sound of things.

 

Alberto-I want to keep this motor as user friendly as I can as it will be a field bike with knobbly tyres for myself and my children to thrash around in the mud. As I have a spare lying around I thought that an ETS banana would be a decent choice probably running with a 19/19 carb.I will be fitting it to an old,damaged ET3 chassis that is doing nothing at the moment.

 

I would appreciate more thoughts on this.Thank you.

[+ curare]

Thank you for your help.Curare,I would have asked over on SIP but it seems you don't look down on the smallframe forum.If it's not too much trouble do you mind if I ask for advice when I build a Polini 50 motor for my daughter?

 

Thank you again.

 

No problem