Polini Speed Engine

[AllanteTopic starterBerichten: 8]

Hi all. I have a question about crankshaft and carburettor for Polini Speed Engine with 46mm Polini cylinder kit.
Can I use std. (regrinded) crankshaft, free from fear of it’s damage and a 21/21 carburettor (of course with a new custom, on the turning-lathe made intake manifold – 21mm = have I to regrind the Speed Engine’s sucking?

Thank’s a lot for answers 🙂

[DriesBijdragerBerichten: 317]

I think you mean a 46mm polini cilinder:)

Probably your engine wil run whit this crankshaft, but it will be beter if you buy a “full” crankshaft.

I hope that I answered your question a little bit.

[AllanteTopic starterBerichten: 8]

Dries :
I think you mean a 46mm polini cilinder:)

Probably your engine wil run whit this crankshaft, but it will be beter if you buy a “full” crankshaft.

I hope that I answered your question a little bit.

Yes, 46mm. Sorry, bad mistake.

[EdjuhBijdragerBerichten: 6956]

Don’t touch the inlet! I think the best thing to do is to use a STD. crankshaft because it will perform best in low and midrange whereas a race crank only @ higher rev’s.

A piaggio crankshaft(rod?) is strong enough.

[DriesBijdragerBerichten: 317]

no problem!;) we understand what you mean;)

[viciousBijdragerBerichten: 337]

Dries :
I think you mean a 46mm polini cilinder:)

Probably your engine wil run whit this crankshaft, but it will be beter if you buy a “full” crankshaft.

I hope that I answered your question a little bit.

DO NOT, I repeat, DO NOT mount a full-cheeks (or whatever it`s called in English) crankshaft into a SPEED ENGINE. These `full` crankshaft are used in the EVOLUTION ENGINE, because it works with a valve steered intake. Your SPEED ENGINE uses the crankshaft`s gap cut out of one of the cheeks (crank steered intake), so you have to use the `normal`, conventional crankshaft.

[ArvidWDonateurBerichten: 6258]

But he sais that he want’s to use a dellorto 21mm carburetor, i suppose he is going to use a side-inlet on his momped like the one of simonini.

Or do you want to mounth the 21dellorto on the inlet on the back of the engine ?

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[.-{2F4OV}-.]

Cause if you use simonini side inlet a ‘full cheecks’ crack is possible. If you use the normal inlet you’d use the standard crack.

I don’t think you want to mount the 21mm carburetor on the back.. do you? Because you can never make the inlet of a speedengine big enough…

[viciousBijdragerBerichten: 337]

Maybe it would be easier if you gave us some more details about your intentions.

[AllanteTopic starterBerichten: 8]

I want to make a 21mm intake system on the Speed Engine, but in Czech Republic, there are no products for Ciao (only Polini). So I can’t buy a Simonini side intake system. So I decided to do this:

My uncle can make me the “removable intake extension”, same as the Speed Engine have on the back for 13mm carburator, but for 21mm carburator, and than I will make a bigger intake hole on the Speed Engine.

Picture of plan:

So, is it possible?

[diacBijdragerBerichten: 2184]

u have to cut very much from your ciao if you wanna make that 21mm carb fit..:con

[ArvidWDonateurBerichten: 6258]

Yes it is possible:)

No it is not usefull with a 21mm dellorto, maby a 17-18mm will work but you will not be able to get all the air from the 21mm dellorto trough the small hole in the speedengine. (not even if you make the hole bigger)

But is worth doing it because a 17mm will preform so much better than a 13mm carburetor

I suppose you will have some problems fitting the big carburetor because there is not so much room behind the engine for mounting a huge carb 😉

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[AllanteTopic starterBerichten: 8]

ArvidW :
Yes it is possible:)

No it is not usefull with a 21mm dellorto, maby a 17-18mm will work but you will not be able to get all the air from the 21mm dellorto trough the small hole in the speedengine. (not even if you make the hole bigger)

But is worth doing it because a 17mm will preform so much better than a 13mm carburetor

I suppose you will have some problems fitting the big carburetor because there is not so much room behind the engine for mounting a huge carb 😉

And what about 19mm carb.? 🙂

[CrullieDonateurBerichten: 2279]

I’m afraid that carb will not fitt because there is not enough space for a bigger one, but if your uncle make an intake with a bend than it will maybe work. And try to find a small as possible carb.

I also try to find a way to make it happen. Its not easy. =)

I’m using a pressure pulse carburator 17 mm and believe that this is the best size for the speedengine.
maybe your uncle also can make on for me 8)

TICKLING BARN

[AllanteTopic starterBerichten: 8]

Crullie :
I’m afraid that carb will not fitt because there is not enough space for a bigger one, but if your uncle make an intake with a bend than it will maybe work. And try to find a small as possible carb.

I also try to find a way to make it happen. Its not easy. =)

I’m using a pressure pulse carburator 17 mm and believe that this is the best size for the speedengine.
maybe your uncle also can make on for me 8)

If I will make that intake pipe curved up like this:

Than I will have maybe space for 19mm or 21mm (they are same size) carb. 🙂 🙂

[Gebruiker]

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