drilling jets
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Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2285

Sun Sep 13, 2020 6:03 pm quote
I'm trying to confirm the proper way to enlarge a jet , I have a 100 here and in the drill Microbox HSS twist drill set it says its a the 10 , I measured it with the caliper and it says its .95mm, so it sounds simple enough that the three sizes match the 100 jet.
Big question is what drill bit size do I use to make this 100 into a 125 or there abouts? Nest size up drill bit says its a 12 and measures to 1.20mm , safe to assume this is drill bit to use to make this 100 jet into a 120? Next drill bit size is then a 13 and measurement is 1.25mm so would this be the Bingo bit to turn this 100 into a 125? Just want to make sure I'm reading into this correctly.
Thanks
Guys

sept 13 drill.jpg
Tools available to measure bits

sept 13 drill 2.jpg
.95 or number 10 drill bit fits this 100 jet

sept 13 drill 3.jpg
measured and says .95mm

sept 13 drill 4.jpg
measured number 12 drill bit and shows to be 1.20mm

sept 13 drill 5.jpg
measured drill bit number 13 and shows to be 1.25

Molto Verboso
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1116
Location: Rochester, Minnesota
Sun Sep 13, 2020 6:42 pm quote
Lynnb wrote:
I'm trying to confirm the proper way to enlarge a jet , I have a 100 here and in the drill Microbox HSS twist drill set it says its a the 10 , I measured it with the caliper and it says its .95mm, so it sounds simple enough that the three sizes match the 100 jet.
Big question is what drill bit size do I use to make this 100 into a 125 or there abouts? Nest size up drill bit says its a 12 and measures to 1.20mm , safe to assume this is drill bit to use to make this 100 jet into a 120? Next drill bit size is then a 13 and measurement is 1.25mm so would this be the Bingo bit to turn this 100 into a 125? Just want to make sure I'm reading into this correctly.
Thanks
Guys
I have two packages of those, they didnít measure according to the box labeling either. You could always make it a 120 try it, then drill it out to a 125.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2285

Sun Sep 13, 2020 6:47 pm quote
That is true Christopher, I could try to make it a 120, supposedly though these are supposed to be numbered bits and I think or who am I kidding? I have no idea if they should be accurate to the jets.
Hmm the jets are in mm right?
Molto Verboso
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 1781
Location: california
Sun Sep 13, 2020 9:51 pm quote
Gents - I have have had more luck with jet reamer than with bits.
Lynn - a 1.20 MM bit is a 120 jet
- a 1.13 is a 113
- a 1.17 is a 117
And so on.
You wont be able to find drill bits in such fine increments.
The reamer seems to do a good job of allowing you to really control the sizes.
Having a basic kit with a range of jets isn't such a bad idea either.
BGM and SIP both sell full kits - and Mercato and others here in the US cary them.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2285

Sun Sep 13, 2020 10:04 pm quote
charlieman22 wrote:
Gents - I have have had more luck with jet reamer than with bits.
Lynn - a 1.20 MM bit is a 120 jet
- a 1.13 is a 113
- a 1.17 is a 117
And so on.
You wont be able to find drill bits in such fine increments.
The reamer seems to do a good job of allowing you to really control the sizes.
Having a basic kit with a range of jets isn't such a bad idea either.
BGM and SIP both sell full kits - and Mercato and others here in the US cary them.
Thanks CM as long as I can drill to be in the neighborhood to define over rich.
Ossessionato
2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: 26 May 2013
Posts: 3992
Location: That bushfire place
Mon Sep 14, 2020 4:23 am quote
My all-time fav PHBH jet...
Many moons ago, while on my first Scooter Rally, Speedy was having richness issues (hmmm.... nothing much has changed there!) & I went to a scooter mechanic, he hand-drilled a jet, & while he hole is kinda Triangular, its STILL the best jet EVER, & the default whenever tuning issues arise!

So, go for it with drilling them yourself, use the ones that are far too small for your needs, then it doesn't matter if you stuff it up.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2285

Mon Sep 14, 2020 3:01 pm quote
Re: My all-time fav PHBH jet...
SubEtherBASS wrote:
Many moons ago, while on my first Scooter Rally, Speedy was having richness issues (hmmm.... nothing much has changed there!) & I went to a scooter mechanic, he hand-drilled a jet, & while he hole is kinda Triangular, its STILL the best jet EVER, & the default whenever tuning issues arise!

So, go for it with drilling them yourself, use the ones that are far too small for your needs, then it doesn't matter if you stuff it up.
Thanks for confirming , yep I did some drilling.
Molto Verboso
2005 PX150 In a Love-Hate Relationship with a 2-Stroke Vespa Since 2007
Joined: 01 Sep 2007
Posts: 1845

Tue Sep 15, 2020 1:26 pm quote
Here's a handy chart that shows the equivalent sizes in inches and mm of 'wire drill' size bits.

A 'set' of bits may not contain the in-between sizes and they may be special order or something you'd have to buy at a tooling shop.
And I'd still mic them.


https://www.uboltit.com/pdfs/drill-bit-conversion-chart.pdf
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2285

Tue Sep 15, 2020 2:18 pm quote
pdxjim wrote:
Here's a handy chart that shows the equivalent sizes in inches and mm of 'wire drill' size bits.

A 'set' of bits may not contain the in-between sizes and they may be special order or something you'd have to buy at a tooling shop.
And I'd still mic them.


https://www.uboltit.com/pdfs/drill-bit-conversion-chart.pdf
Thanks appreciate the extra cross over information.
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