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Hello, I'm going to update my Polini cylinder to 58mm because I had a small problem with the piston. The engine still work with 20hp but there are small marks inside... I will then rework the exhaust port to reach the 70% with the new GS piston and I need your advise. My old exhaust port use to look like the B model, but I saw that the Dittmar's one (http://www.vespa-hamburg.de/pages/index.php) is a bit different and more straight on the sides. What is the best shape for the exhaust ? Is there document that shows the construction of the shape with minimal radius, etc ? Thanx

Anyone knows what is this seat ?

Hello, I did the modification on the polini reed valve to use it with a Keihin 33 but I think I have cut the midle part a little bit too low... What do you think ?

Hello, Sorry to change the subject, I saw this intake on this thread, where can i find one ?

Mad Max !!!

Hello, When machining the bottom of the engine casing, can we use the side of the engine as a reference ? When the machinist did it on my engine casing he told me that it was probably the reference used by piaggo to make all the mahining operation on the casing (drilling, bearing surfaces...). Right or wrong ?

Things have a bit changed since last year... I have updated the diagrams to 192/127,put a 3.00 primary ratio, reworked / optimised the exhaust, i use the DRT clutch, a frantz exhaust, the piston clearance is far away from 7/100 but it seems to work well

Hi, i'm looking for the shockabsorber plate of the following picture, the model B. I don't excatly know what is the model of Vespa equipped with this model. Cheers

Hello, i'm looking for a PV/Et3 handelbar. Thanx Antoine

Hallo, Ich suche ein PK XL gabel für meine primavera. Danke Antoine

Arf.... I sould have ordered the DRT disc kit... Articolo FS 170/DF04 http://www.drtdenis.com/catalogo/sottocat.htm%20DBE?idcat=33 KIT DISCHI FRIZIONE x 170/E/K 04 DISCHI guarniti 2.50 mm 02 DISCHI acciaio 1.50 mm 01 DISCO acciaio 1.00 mm Già con alette piegate pronti all'uso Se ordinati con 170/E/K saranno installati nella frizione

Hello, I have a problem when i use my Drt clutch with surflex cork plates (2mm) and friction plates (1mm). The friction plate touch the outer clutch plate before the cork plate and the surface for the thrustplate is 2mm higher than on original clutch : There is a tip on Sip: SIP-TiP: always order the V50/ PV plates when purchasing this clutch. Denis personally recommends the 4x 2.5mm cork plates in combination with 2 friction plates measuring 1.5mm and a 1.0mm friction disc. However, some trial and error experimentation will be the best way to find the right combination that fits both the engine and your personal preferences. Where can i found this kind of plates ? Thanks Antoine

Hi, Here is a bottom view of the polini 130 cylinder. What is the ideal shape for the exhaust ? I increased its size to fit with the GS piston, and i have make something like the A drawing. Thanx

Hi, i'm looking for a worb5 Special Lip Crankshaft in good stand for smallframe. Thanx Antoine

Is the difference between the race mazzu and the lipped by worb 5 only on the masselot of clutch side ? Do they only remove the lip or do they made other modifications ?

I will recheck my measurements, i don't know where the difference comes from, i have a gravedigger cylinderhead with 1mm squich, and when i take measure of the squih with tin (pewter ?) i obtain 1mm so my TDC should be the top surface of the cylinder. Concerning the exhaust port the base of the port is higher than the piston can i remove the 1mm like on the picture ?

Yes it does, why don't i find this measures with my graduate disc and 0,2mm block part, i have check it before removing the cylinder i found 186 / 121°... However i will make something like this:

Here is a portmap of my polini 130 cylinder: I found 41,5mm for the width of the exhaust map, so it makes 66% for a 57,5mm diameter. If i want to reach 70% i should increase the portmap width to 44,59mm (40,25 linear) I also took pictures of the exhaust port: http://picasaweb.google.fr/fleuryantoine/Polini130Exhaust# Edit: The inlet port is 39,6mm on clucth side and 39,2 on ignition side.

Hey !!

That's clear, i will try to use the port mapping calculator, what is the size of the conroad and its stroke on mazzuchelli ?

Because i thought it was a problem when the bottom of the port were higher or lower than the bottom of the piston. So i though it was necessary to increase the bottom of "X" on my drawing.

Yes that's a race engine but if i raise the cylinder i will have to work the bottom of each port, exhaustport , inlet port, 3rd port, isn't that easier to work only on the top of the inlet port without raising the cylinder ? I will ask Mathias for the ideal timing of his exhaust.

- I will check the ignition with my strobe light asap. - For the 70% schould i take the width measure on the portmap or the measure directly on cylinder ? I think "Sehnenmaß" is more logical - To raise the 126° i really don't know, i know that it's dangerous to touch the shape of the inlet ports, but i would like not to use a spacer..... any aproximative idea of how much millimeters i should increase ?

Thanks FalkR, for the vespatronic i have adjusted it like on the picture bellow. I'll take all the measure for the exhaust tonight, the inlet port is the polini original, and for the exhaustport width i'm far from the 72% ? allowed by the gs piston. the exhaust flange is 32mm diameter (i have adjusted it for the pm40).

I will make a portmap and take pictures tonight, i didn't update the exhaust port since i put the GS piston...