Vespa Inlet Porting

[DickieD]

I've got my hands on a Polini 210 with Polini 60mm crank and have just matched the casings to the barrel. I now need to modify the carb inlet, looking at the supplied instructions it looks as though you have to elongate it by 4mm. My question is do you do this at the back end of the port the furthest away from the barrel and to the inside only? I'm almost sure you do but would like to make sure before I start removing any ally.

Any help would be greatly appreciated.

Link to instructions below.


http://www.sip-scootershop.com/App_Them ... ns/pdf.gif

[DickieD]

That link didn't work I'll see if this works.

https://www.flickr.com/photos/138247792@N08/sh

[Norrie Bodge]

Few pics here may help - http://modernvespa.com/forum/topic87680.2

[DickieD]

Cheers Norrie I'll have a look.

[DickieD]

Not sure if that last link worked either but here it is again if anyone can help ta.

https://www.flickr.com/photos/138247792@N08/sh

[sean brady scooters]

the way i do it and would suggest is as follows.Firstly determine how much overall inlet timing you want, for a torquey tune prob 180 degrees max /longer for a revvier tune .
then dry build the top end with crank,piston and barrell fitted /with a spacer if required .and use a timing disc.
Then turning it over you would ideally want the intake to open roughly about when the piston closes the transfers or slightly after ..mark and measure this and alter to suit by removing the nessesary alloy from the REAR of the intake port .
then take your chosen inlet timing figure from this starting point to give you the closing position .

[DickieD]

Thanks Sean, I was just going to remove 4mm from the rear as per instruction but I will have a go the way you suggested to make sure it's right.

Do you open all of the inlet or taper it down leaving the top of inlet hole the same size?

[sean brady scooters]

if your using the standard carb in the air box just blend and flow it through ,you can also if you wish modify the carb a bit under the slide ..if using a bigger carb on a bigger manifold ,again just blend all parts to match ,try and maintain a smooth/even transition shape throughout as much as poss

[DickieD]

Ok Sean many thanks for the advice much appreciated.