Drilling out pilot jets

jdallen · Posted: January 5, 2009, 1:04 am Post subject: Drilling out pilot jets

I have gathered a range of pilot jet sizes.....27.5, 32.5, and 35.......but I think the size I need is a 30. I've got an extra set of 27.5's, so can I drill those out to a 30 and will they work well, or is this a waste of time? Do the small holes on the sides of the VM22/bs38 pilot jets increase with pilot size or stay the same?

What's the best way, drill press or one of those hand held drills you have to crank by hand?

xsjohn · Posted: January 5, 2009, 1:27 am Post subject: Re: Drilling out pilot jets

Can be done but not with a drill......have to use exact sized guitar string and jam it in there....I do it all the time........but I have the right string for what hole I want......and a “good” micrometer……..

a .3mm (30 pilot jet) would be a .0118 or almost a 12 thousand guitar string….noticing a .325mm jet (32.5 jet) would be a .0128 guitar string….almost 13 thousands……..and a .275mm (27.5 jet) would be a .0108 or almost an 11 thou guitar string……easy……….

And the marking on the guitar string pack is usually never what size the string actually is.........""have"" to measure with a micrometer.........and get the burr from cutting the string off theend with a stone so you aren't jamming a burr in there.............hold the string with pliers and take some time pushing it in there......feeling the spinning pressure once it penetrates....and doing the second one the same way.......easy......

www.kitchencabinethard.../Pop2.html

thank you John

xsjohn

yamaman · Posted: January 5, 2009, 7:54 am Post subject: Re: Drilling out pilot jets

Yes, drill bits exist for this purpose. You have to be careful & it's best to go up one drill size at a time. Best to use a thumb drive - not a power tool:

www.hobbytools.com.au/prod325.htm

xsjohn · Posted: January 5, 2009, 9:18 am Post subject: Re: Drilling out pilot jets

That's cool..............but it starts a .35MM..........and only goes to 1MM.....to big for some BS38 pilots and too small for any main jets...........

xsjohn

yamaman · Posted: January 5, 2009, 9:53 am Post subject: Re: Drilling out pilot jets

Only an example of whats available John, this is only one shop, other sizes available for sure:

www.hobbytools.com.au/prod858.htm

www.hobbytools.com.au/prod859.htm

xsjohn · Posted: January 5, 2009, 10:22 am Post subject: Re: Drilling out pilot jets

Sometimes off sizes are what is needed........example I use a 46 pilot in my BS34's........45 using a .018 guitar string =46......

xsjohn

yamaman · Posted: January 5, 2009, 10:45 am Post subject: Re: Drilling out pilot jets

Maybe these John:

www.hobbytools.com.au/prod736.htm

drifter · Posted: January 5, 2009, 12:16 pm Post subject: Re: Drilling out pilot jets

xsjohn wrote:

That's cool..............but it starts a .35MM..........and only goes to 1MM.....to big for some BS38 pilots and too small for any main jets...........

xsjohn

Having been a watchmaker, I can tell you that drill bits are available in pretty much every size imaginable. All you need to do is search. Also...bits are not that hard to make either. Used to make them all the time for watches and clocks.

Dave

xsjohn · Posted: January 5, 2009, 4:28 pm Post subject: Re: Drilling out pilot jets

All this retorick will teach me not to mention a simple way to do it..........xsjohn

yamaman · Posted: January 5, 2009, 5:22 pm Post subject: Re: Drilling out pilot jets

Keep it up please John, your ideas and thoughts are always treasured by most on this site. Your way is a fine idea and I see the merit in it. I also play guitar and have a endless supply of strings. I don't however have a micrometer, so for $20 I can buy a set of number drills and do it that way. I wouldn't like to own a $20 micrometer.
ore options the better!

tito650 · Posted: January 5, 2009, 9:28 pm Post subject: Re: Drilling out pilot jets

ahhh but drill bits are only as acurate as the hands that hold them. done wrong the right drill can make a hole bigger than u planned . sounds like johns got the math worked out Very Happy

! being a machinist i wouln't dream of doing any thing with out my micrometers or measuring tools ! and as for drill bits from hobby stores. mmmmmmm ? key word hobby. i don't see how they can be that accurate. i wouldn't trust them. best thing to do is start measuring like john did , then u know for a fact what size that hole is.

jdallen · Posted: January 5, 2009, 9:52 pm Post subject: Re: Drilling out pilot jets

XSJohn, a .012 guitar string is a high E, I believe. Is it sturdy enough to make the hole bigger? Do you twist it as you push it in, and do you use acoustic or electric guitar strings?

Thanks John

jayel · Posted: January 5, 2009, 9:56 pm Post subject: Re: Drilling out pilot jets

I use acyltelene (gas torch) tip cleaning bits (comes with a holder chuck) or you can find # drills but yes you better measure them before you use them and even then shaky hands make for shoddy work, I put my little bitty bit into its holder chuck and then that into my drill press chuck which I turn into the jet by hand... had to do this on my 450 honda as jets are no longer availible, had a couple of over sizes so soldered them shut and then re-drilled to size

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

The air bleed holes in the sides of the VM22/210 type pilot jets don't make any difference in the '76-'79 carbs, in fact they're not even needed. Some of the originals had none. This is because the pilots in these carbs mount "upside down" and flow in reverse. Air is added above the jet so the bleed holes in it's sides do nothing.

xsjohn · Posted: January 5, 2009, 11:38 pm Post subject: Re: Drilling out pilot jets

Going up one jet size would be all I would expect from the 12 thou string...may need to go up in stages..took a bit of pushing and twisting to go from 42.5 to 46 on mine...used some fine valve grinding compound......actually used a 17 then and 18 to do it....was about 16...guitar shops are handy and electric or acoustic strings makes no diff.............mark the string pack for future use and remove the original jet size marking......don't know how you would remark.....maybe make a code .....1 line equals ...2 lines equals ect....small file......

Being able to go in between sizes tickles the "s" out of me.......finding a jet that uses about 1 1/2 to 2 turns is probably good as it gets.....too big and the movement of the screw gets to radical.....too small and decel sucks...........

www.kitchencabinethard.../Pop2.html

xsjohn

tito650 · Posted: January 6, 2009, 12:48 am Post subject: Re: Drilling out pilot jets

john i c where your going with the guitar string. it's a very good idea. your not using it so much as a drill but more a reamer. wich is going to give u a cleaner smoother more accurate hole. i bet that would make tuning a lot easier . no pun intended Laughing

starrett link below has got some good converson tables. i love starrett tools!

catalog.starrett.com/c...1&Mode=REF

xsjohn · Posted: January 6, 2009, 1:05 am Post subject: Re: Drilling out pilot jets

Tuned like a piano.....with the CR decreased just a half bit I would venture to say I have the smoothest xs out there......up the express ramp in 4th and 5th @3700 at 70mph and gone......no vibes no noises...........18/29.......finally being a skinny ass at 135lbs has paid off...and I can go somewhere without the normal xs hassels.....feels like a different bike now.....did 60K with the cr beating it to death is now gone "forever".... pushing 68K and Very Happy

Had to think out of the box before I nailed it...........

www.youtube.com/watch?v=JBUtNWD7_bs

xsjohn

yamaman · Posted: January 6, 2009, 10:38 am Post subject: Re: Drilling out pilot jets

A list of some available drill bits:

www.madison.k12.wi.us/...drills.htm

jayel · Posted: January 6, 2009, 11:45 am Post subject: Re: Drilling out pilot jets

xsjohn wrote:

Tuned like a piano.....with the CR decreased just a half bit I would venture to say I have the smoothest xs out there......xsjohn

you need a old H-D WL 45cu.in. (750cc) flat head john like they used in the three wheeler Servi-car, idle all day and not over heat of course top end was only about 60mph but at least you wouldn't be getting blown off the back by the wind

xsjohn · Posted: January 6, 2009, 12:27 pm Post subject: Re: Drilling out pilot jets

""""getting blown off the back by the wind""""

Could just ride down wind all the time....and tack my way back home.... Laughing

xsjohn

tito650 · Posted: January 6, 2009, 9:52 pm Post subject: Re: Drilling out pilot jets

wow a H-D sevi car that was a wile ago ! all they make any more are trailer queens lol. no wind in there Laughing

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