Hello,

I'm working on a new engine for a daily scooter.

The idea is to use the engine casing without weelding it.

Here are the parts I already have.

Short 4th DRT

Clutch DRT 8 springs

Koso 28

Polini reedvalve manifold with a fitted 28mm intake

2,86 with repair kit

Mazzu anticipated

ET3 ignition with 1,8kg Sip flywheel

PM40 exhaust or maybe Sip Road

I would like to use a cylinder without touching it too much, maybe the exhaust port but that's all.

So I think I could use:

- Polini 133 Iron

- Parmakit Aluminium touring (not the SP09 but the one with small transferts)

- M1

I saw on another M1 post that the timings of the M1 are lower than on a Polini... but i think i remember than the PM40 need 185° to work well at the exhaust port.... so what's the best choice for a punchy scooter ?

The thing is that I have already ordered the M1 on Sip, and I'm a bit disapointed now that I have seen the other post...

What do you think ?

Thanx

Antoine

Bearbeitet 7. Dezember 201114 Jr. von keuk

why not the new aluminium polini EVO?

send the m1 back

Bearbeitet 7. Dezember 201114 Jr. von heizer

the new aluminium polini EVO?

Only raise the Exhaust port to 30° Blowdown and there you go.

Bearbeitet 7. Dezember 201114 Jr. von Brosi

why not the new aluminium polini EVO?

send the m1 back

Because the transfert ports are too big on the Polini EVO and i don't want to weld the engine casings.

Bearbeitet 7. Dezember 201114 Jr. von keuk

Afaik there´s no need to weld.

Really ? Ooooh damned !! that's why they made this little edge inside the transfert port !! I thought the transferts were like a modified Quattrini but in fact their are more tight ?

Bearbeitet 7. Dezember 201114 Jr. von keuk

So it would fit like that ? (That's a Photoshop)

the evo kit would be my 1st choice for an engine like you want it.

if you don't open the transfers, you don't have to weld the casing

So it would fit like that ? (That's a Photoshop)

maybe the transfers a little smaller, but yes, it will look like this.

Right. But you have to remove the "noideawhatitscalled". Just take a look at the official manual: http://www.gsf-shop....44534821536.pdf

Bearbeitet 7. Dezember 201114 Jr. von Brosi

Thanks for the advises guys ! So it will be a Polini evo to stay in the Polini family with my racer !

I will try to get rid of the M1 then...

One more question, I just took a look on the official manual, the Polini EVO has the same timings than the M1, 178/126, is there a big difference between both cylinders ? Of course the price, but for the performances ?

Yes. The scavenge angles of the transfer ports does differ a lot. Where the M1 ist "designed" for high RPM the Polini has a reasonable mid and low rpm design.

High RPM meaning 10000 plus, mid an low everything below.

Alles klar, danke !

Bearbeitet 8. Dezember 201114 Jr. von keuk

Eine neue frage: Now that I have both cylinders.... M1 and Polini EVO, is the M1 a good choice to replace my old full machined Polini iron cylinder on my racer ? I have to choose between a upper size for my GS piston or something else...so maybe the M1 should be a possibility.