Expected top speed?

[Dea_944tTopic starterBerichten: 87]

I have the following eninge configuratino on my 1973 Ciao

Polini Speed Engine
Polini 46mm cylinder
Origiginal moped crank
13/13 mm carb
Polini air filter with extra holes according to Polini spec
Sito Plus 45kmh/ exhaust (ref nr 0248) possibly also called Sito Citypower

I started with a fairly low gearing as I wanted quick acceleration, giving a top speed (GPS) of 60km/h whoch gave great acceleration and made it really strong.

I then tested with a 16% smaller rear pulley but only got a 10% speed increase, 65 km/h.

I was expecting higher top speed from this engine, could it be the exhaust that is limiting?
In the latest exhaust test it did seem that the Gianneli Original Power gave a lot of power and looks fairly original, could that be a better choice?

[MartinoModeratorBerichten: 7384]

Yes, the exhaust is your limited factor for top speed, but i don’t think there is much difference between the Giannelli Original Power and Sito +. We did not actually test both of these pipes, but i don’t think there are much better exhausts which do look original. You should go for an expansion pipe for more top speed.

Link naar Mijn collectie / Projecten.

[Dea_944tTopic starterBerichten: 87]

Thanks, I had some hopes it might be better as it performed as well as the Leovinci SP.

I asssume that the Proma City Power is about the same as well?

[ritzeBijdragerBerichten: 3421]

The gianelly city power Wil give some hi rpm, I drove it with a 46 malossi and a reedvalve engine and got a top speed of around 75/80kmh. It wil go into the 8.5k rpm zone witch is pretty good.
Even with a moddded 50cc it will do a good 65 kmh
(this is with a cvt gearbox)

De budget beun tjoener: geen geld is te duur of het werkt nog niet
Link naar Mijn collectie / Projecten.

[zevenenergieDonateurBerichten: 4167]

I assume you have edited the crankcase, the inlet and the booster ports. For more power you can also change the timing of your crankshaft.

How to: Krukas tuning berekenen

[Dea_944tTopic starterBerichten: 87]

I was under the impression that no modifications were needed on the Speed Engine crankcase?

[ritzeBijdragerBerichten: 3421]

I also think that you shouldn’t have to tune the timing in your crankshaft. The speed engine has already a fierce timing. Unless Yall wanna get some screamin hi rpm engine block 🙂

De budget beun tjoener: geen geld is te duur of het werkt nog niet
Link naar Mijn collectie / Projecten.

[zevenenergieDonateurBerichten: 4167]

I also think that. I didnt know you had a speedengine

[Gebruiker]

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