Guys, I have a DJ kit on the bench and plan to put it in this Friday. The bike, is a PITA to start when cold so I want to drill the choke jet while I have the carb out. I had a bit lined up but ultimately the guy didn't have one that small. 18 thousandths is tiny, like a normal overbore on an engine. You can barely catch your fingernail on a 10 thousandths lip in the bore.

Seriously? 18 thousandths?

The question I have now is where do you find them? Am I best searching local hobby shops, harbor freight, hardware stores? Any ideas? I can't mail order them in time so I will be zipping around looking for an actual bit.

Thank you

 

A good hobby/model shop is probably the best source. There may be some online sources too. In the old days these kits were more available for carb jet drilling and tuning. Yeah, the increase in the hole is small, but if you think about it, jetting step sizes usually are small.

 

Also, look for a #77, which is the same size.

Size chart: http://bobmay.astronomy.net/misc/drillchart.htm

Google for "wire gage drill bits"

There are a lot of places, here's one chosen at random:

http://www.gyrostools.com/Drill-Bits..._53/index.html

 

Got mine from a local hobby shop. Two bits in the pkg for $2.

 

The hobby shops in my city have so far referred me to home depot and harbor freight. Odd. The local shops include nitro RC car places that would be futzing with carb jets too. They actually claim great luck at home depot for small bits. Will let you know.

I had a nightmare last night about this teensy drill bit snapping off inside the jet. This thing should be barely bigger than a strand of hair.

 

Highbeam, it won't be as "hairy"...pun intended...as you think to drill out this jet. The brass is super soft, and you'll know when you've gone through the jet and are touching the pot metal of the carb. In fact, to ease your mind, get a strand out of a wire brush or such and poke it into the jet hole. You can feel where the metal strand stops and hits the carb body. Don't worry. You can't drill or do any damage to the carb body with this tiny bit. And of course, use the bit by hand and not in any drill motor.

 

I bought a couple of them from an Amazon seller. $1.10 each, $5 to ship.

 

Our Home Depot didn't have anything close...and referred me to Ace...which new what they were talking about and referred me to the hobby store. funny.

 

My bike is the same way. Really slow to get going.

How or what will this do? Sorry for the newbie Q, trying to learn/understand what I may be able to do to help.

BTW, I have a "new" TBR exhaust coming from TBR and a DynoJet kit is probably in the works for when I have my first service.

Thanks.



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If you go to Harbor Freight, I would avoid the solid carbide bits they sell. These are left overs from plants that Mfg circuit boards. They are good bits, but carbide is unforgiving when flexed, and will break. Drilling by hand you need the bit to flex some as you will not be able to hold it exactly centered while rotating it. Steel bits will flex/bend without breaking while you auger out the hole. A pin vise is the best tool to hold the bit with, but I was able to get my bit centered and held in my x-acto knife. If you do that make sure it's centered, and parallel to the handle.
Dan