drilling jets

considering i have four spare carbs for my 2 opposed twins, would it be a good idea to try and drill out the jets a lil bit bigger on one? if so, how much would improve fuel flow, and how much would be to much?

I'd watch out how far u do this could have the engine to rich. Then the carb would be useless

thats what i was thinking, but i would only go like a 16th bigger

richie thomas wrote:

thats what i was thinking, but i would only go like a 16th bigger

I'd start with a 64th, A 16th is .0625 ", Thats a lot when it comes to jets

If you care, .0625 is pretty much double the spark plug gap on an average engine

thanks, give me some wood or metal i can bout build whatever you want, give me a motor and im as lost as a fat kid at fitness camp
ima do it at school so should i get a drill bit that will almost fit in it or what?

Find the biggest bit that will fit in the jet, then go to the next size up in the smallest increment possible. Usually 1/64:, unless there is a letter or number size that comes in between.

I use a pin vice, has bits so small I can't see them with out my glasses on. You can get them at welding supply stores. They are sold as torch tip cleaning drills. Hobby shops sell them too.

thanks chopper, i have a really reallly small set of round files, would these work?

Nope

I use a pin vise and numbered bits to drill my jets, too. But nobody has yet mentioned this:

You gotta let your engine tell YOU what it needs. Read the plug. If the insulator (conical ceramic part that the center electrode sticks out of) is really light or even white, you're lean and would benefit from a larger jet. If the insulator is a medium tan to chocolate brown, don't mess with it. Your mixture is already where it needs to be. If the insulator is black, you're too rich and need a smaller jet.

Also- make sure everything else is okay. A carb gasket leak can make things rear too lean even if your jetting is correct.