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@zachyzach avatar
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'64 VBBs, '74 BMW R75/6 airhead, '74 Bultaco Alpina 250, Lambrettas + projects
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@zachyzach avatar
'64 VBBs, '74 BMW R75/6 airhead, '74 Bultaco Alpina 250, Lambrettas + projects
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UTC quote
I should have taken the NSM bot's advice and just started a new thread. So here goes.

Since most discussions on air filter "heart" drilling for tuning purposes are pretty old -- and views were hotly contested back then! -- I'd love to know, what are folks' newer experiences?:

Question is, whether to drill out a 5mm hole in the heart cutout of the air filter on a stock dell'orto SI 20/20D as recommended by Pinasco for its iron 177cc 2-port kit (to open up air flow above the main jet stack).

I rebuilt a 1964 VBB2 motor, added the Pinasco top end, using the aforementioned 20/20 carb and will run a Malossi Power Classic big box exhaust. I have a supply of main jets up to 110, tho I'm missing a 108 size currently.

Anyone have recent experience, good or bad? Did it screw up the jetting as some previously reported? I don't have lots of tuning experience And I have only one original air filter.
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⚠️ Last edited by zachyzach on UTC; edited 1 time
@christopher_55934 avatar
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2007 Stella 225
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Location: Rochester, Minnesota
 
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@christopher_55934 avatar
2007 Stella 225
Joined: UTC
Posts: 3547
Location: Rochester, Minnesota
UTC quote
zachyzach wrote:
I should have taken the NSM bot's advice and just started a new thread. So here goes.

Since most discussions on air filter "heart" drilling for tuning purposes are pretty old -- and views were hotly contested back then! -- I'd love to know, what are folks' newer experiences?:

Question is, whether to drill out a 5mm hole in the heart cutout of the air filter on a stock dell'orto SI 20/20D as recommended by Pinasco for its iron 177cc 2-port iron kit (to open up air flow above the main jet stack).

I rebuilt a 1964 VBB2 motor, added the Pinasco top end, using the aforementioned 20/20 carb and will run a Malossi Power Classic big box exhaust. I have a supply of main jets up to 110, tho I'm missing a 108 size currently.

Anyone have recent experience, good or bad? Did it screw up the jetting as some previously reported? I don't have lots of tuning experience And I have only one original air filter.
I say chuck the entire filter and put one of these on, bypasses entire drill or not to drill debate. When I can go from rich to lean by removing a filter it's a choke point for performance.

https://www.shapeways.com/product/ZFBJ7HCAE/20mm-largeframe-vespa?optionId=451888&li=marketplace


If I had to vote "drill", that filter is setup for a standard cylinder and exhaust that was about 8hp. .
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@zachyzach avatar
UTC

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'64 VBBs, '74 BMW R75/6 airhead, '74 Bultaco Alpina 250, Lambrettas + projects
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@zachyzach avatar
'64 VBBs, '74 BMW R75/6 airhead, '74 Bultaco Alpina 250, Lambrettas + projects
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Location: Western Mass., USA
UTC quote
Thanks for pointing that out.
As far as drilling out the filter, what have I got to lose.
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Vespas 1964 GS160, 1965 SS180, 1977 V9A1T, 1983 PX150E
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Vespas 1964 GS160, 1965 SS180, 1977 V9A1T, 1983 PX150E
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Location: Siam
UTC quote
zachyzach wrote:
As far as drilling out the filter, what have I got to lose.
A small amount of aluminum?
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