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Polini 130 Grauguss - was kann er wirklich?


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2,52 primary gearing isnt too bad. Sorry i've overlooked that.

How much does the driver weigh if I'm allowed to ask? 

Probably just the 4th gear is too long.

 

Milling the transfer ports to higher duration is not recommended unless you absolutely really know what you are doing. A small failure there will have a huge impact in performance (loss)

 

(Sorry, I cant delete the following link any more on the phone....)

 

The small inlet is not optimal for horsepower, but i have not much experience with that and do not know right now where the limit is with this. 

Which crankshaft inlet duration do you have?

 

Considering that ~10hp are needed for reaching the tip of 100km/h you might have approximarely around 7-8hp. 10-12 hp should not be that big of a deal with your current setup I guess. Maybe double check carb settings and ignition timing just as alfonso already wrote.

And for more torque, putting a spacer under the cylinder is a must with these exhausts in my oppinion.

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Hier nochmal ne frische Kurve von meinem guten alten Polini;) 2 Loch Piaggio Block,54iger Bgm Vollwange,polini Rotax Kolben.Polini Membranblock gedreh Mini V Force 33iger pwk aus der Backe,Falk R Ar

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Hier mal der aktuelle (und hoffentlich finale) Stand von meinem GG-Polini. Alter Gussklumpen 54er Kingwelle FalkR Ares Keihin PWK33 Overrev mit Luftnummer   Polini 1

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Driver weight around 75 kg :-D:-D
Crankshaft duration should be around 135/64. I think that is plenty of duration, maybe too much. 


IMG_20201103_171334.thumb.jpg.c3813152f4061d7ab4412109a0075f98.jpg

But I thought about it overnight and I think that I will mill the rotary valve and plug in the reed valve to maximaze intake flow. Maybe open the inlet ports on the base of the cylinder and keep the (115°/177° = blowdown 31°), because I think that you are right with the milling the port height. 

@skinglouie before he modified his post I saw something like this.
My inlet area        (12.5 mm; 22.3 mm) = +- 279 mm²
Carb area                            (d. 24 mm) = +- 452 mm²

If modified to reed with (20 mm; 30 mm) = 600 mm²
I would maximaze the area that the 24 mm carb uses. My area now would be sufficient for shb 19.19, that has area of +- 254 mm²
Maybe this make sense? I also have conected a functional rotary valve with reed valve together. This could be making a mess also since the reed valve only function on vacuum from cylinder and rotary valve on set timings. 

Again thank you for your help :laugh:

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@msk_motori

 

hello there (where are you from?)

 

Personally i would, at this point not touch the rotary valve yet as i think there is still a lot of potential too be found within your current set up and its a pitty to go havoc on a prefectly fine ol rotary case (as i understood?)

As the fellas before me mentioned already i would just lift the barrel and go up to approx 125/180-182, which are the numbers of my wifes primavera which is with sip road and a PHB30 a blast and super fun to ride!

Furthermore i would recommend that you have a look at the rotary valve housing and open it up accordingly to give enough space for the mixture to easily pass through the bottleneck.

I assume based on my limited Vespa knowledge that with a 24 carburetor that you do not need yet to enlarge the carb entry area outrageously as a area increase there would disturb the (somewhat) homogenous flow of mixture.

 

So based on my (limited) experience i would look towards following procedure:

 

 

raise cylinder

lower top to compensate for raising barrel

enlarge rotary valve not just crank

sensibly enlarge carb intake area

widen exhaust  port in barrel

enlarge transfer foot prints in barrel and crankcase

 

all the best and good luck, let us know how it goes!

 

Christian

Edited by Yamawudri
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vor einer Stunde hat msk_motori folgendes von sich gegeben:

Driver weight around 75 kg :-D:-D
Crankshaft duration should be around 135/64. I think that is plenty of duration, maybe too much. 


IMG_20201103_171334.thumb.jpg.c3813152f4061d7ab4412109a0075f98.jpg

But I thought about it overnight and I think that I will mill the rotary valve and plug in the reed valve to maximaze intake flow. Maybe open the inlet ports on the base of the cylinder and keep the (115°/177° = blowdown 31°), because I think that you are right with the milling the port height. 

@skinglouie before he modified his post I saw something like this.
My inlet area        (12.5 mm; 22.3 mm) = +- 279 mm²
Carb area                            (d. 24 mm) = +- 452 mm²

If modified to reed 
Maybe this make sense? I also have conected a functional rotary valve with reed valve together. This could be making a mess also since the reed valve only function on vacuum from cylinder and rotary valve on timings.

If you're switching to reed valve intake you must remove the rotary intake pad to avoid intake systems interfering resulting in massive intake flow restrictions.

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I would also keep the rotary valve, but enlarge its duct size to match the inlet manifold. There is no need for large engine transfer ports, just match smoothly with the cylinder transfer ports. Also the crankcase timing is not too big. Depending on the exhaust pipe I would just raise the barrel, lower the top and mill the exhaust port in width to increase blowdown area (use GS piston rings).

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Hab hier einen bearbeiteten Polini 133 mit folgenden, per Stichmaß ermittelten Steuerzeiten:

A: 184°

Ü: 122°

Und einer Auslassbreite von 69% mit GS Kopf und GS Ringen.

 

Das ganze soll auf meine PK80s mit 2.56 Primär, BGM Pro Box Auspuff und 19er Vergaser.

 

Wie ist eure Einschätzung zu den Steuerzeiten? Für diese Peripherie mit 31° VA nicht geeignet?

Was sind eure Vorschläge?

Gruß und Danke

 

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vor 20 Stunden hat shanana folgendes von sich gegeben:

Hab hier einen bearbeiteten Polini 133 mit folgenden, per Stichmaß ermittelten Steuerzeiten:

A: 184°

Ü: 122°

Und einer Auslassbreite von 69% mit GS Kopf und GS Ringen.

 

Das ganze soll auf meine PK80s mit 2.56 Primär, BGM Pro Box Auspuff und 19er Vergaser.

 

Wie ist eure Einschätzung zu den Steuerzeiten? Für diese Peripherie mit 31° VA nicht geeignet?

Was sind eure Vorschläge?

Gruß und Danke

 

 

 

ziemlich gut, mit 128 190 hatte ich mit 69er breite und franz aber bei 54x105 25ps.

122 184 kannst aber auch so fahren, passt auch gut.

 

edit: oh scheisse, 19er gaser? 30er gaser mit membraneinlass wär da schon gut damit du die 20ps leicht knacken kannst.....

Edited by Motorhead
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habe gerade den Kolbenüberstand mit montiertem Zylinder ohne Fußdichtung gemessen.

Kolbenüberstand beträgt 5,39mm.

Am Rand korrekt gemessen: 1,29mm

Wenn ich das unterlege komme ich auch sehr komische SZ :sigh:

1608393732907_copy_1200x1600.jpg

1608393732924_copy_1200x1600.jpg

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vor 54 Minuten hat jolle folgendes von sich gegeben:

Kolbenüberstand wird aber am Rand vom Kolben gemessen 

danke für die Info. Ich messe und korrigiere.

 

Edith: es sind 1,29mm Kolbenüberstand

Edited by shanana
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vor 18 Stunden hat shanana folgendes von sich gegeben:

danke für die Info. Ich messe und korrigiere.

 

Edith: es sind 1,29mm Kolbenüberstand

Das würd quasi mit 2,5mm passen, wahlweise Kopf oder Fuß oder beides.

Je nach dem wo du hinmöchtest mit den Zeiten... 

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