Drill size help!

[den35]

I was going to try drilling out the jets on my 5.5 clone and my original Doodlebug engine,but I hit a snag.

All the posts here talk about drills with number sizes(eg,#64 bit).But all my bits are standard measure.(My smallest is 3/64")

Does anyone know what size bit I should use(in standard measure) for each engine?I don't want to use the wrong size and mess up my engines.

[rasndas]

A 3/64 is about a number 56 bit. you will need something smaller than that for your carburetor jets. I just opened the jet on my 6.5 clone this weekend to a number 68 ( stock was a number 70). A 56 would be too rich. What you need is to get an index of small drill bits. McMaster Carr offers one which goes from #61 to # 80. This works really well as you can find which size just fits in the stock jet hole and then drill with the next size up, test and see if you need more.

[den35]

Crap.I was hoping to just use what I had on hand.Oh well.Payday is comming,I suppose.

Thanks,Rasndas.

[cjtmini]

be careful drilling the jets with the tiny drill bits

I put the drill bit in the vise and then "drill" the jet carefully over the drill bit by hand

Start small, you can always go bigger

Number size bits are different than fractional bits

[65ShelbyClone]

Go on Google Images and type in "drill chart". That will give you a cross reference for all the drill sizes; number, letter, and fractional.

The clone carb is in all likelihood a ripoff of the Keihins that Honda uses. If that's the case, then the jets are sized in tenths of a millimeter. A 68 jet has an orifice size of 0.68mm, a 70 jet is 0.70mm, etc. That will help you figure out what assortment of small drill bits you'll need.

[5hpminitech]

adjustable jet from nr racing is only like 15 bucks probably same price as drills and if your off you can just turn the screw instead of buy another jet and start over

[den35]

Hmm.That's an idea.I know they make them to fit the clones.But what about original DB30 engines?