Drilling out jets

I've heard of ppl doing it...but does drilling out your jets really wise..

I don't think so. Jets are pretty cheap.

jets kits are alot of money that i dont have for more power...i need more fuel but cant afford the jet kit right now..

Jets not only have sizes but have internal profiles that you will not be able to duplicate even with the correct size drill bit.

Stick with the kits. They're too cheap to compete with.

KZCSI

where do guys get jet kits cheap...?

Doug's Cycle Shop
Highway 24 W
Salisbury, MO 65281


Phone: (660) 388-6159

You don't need to buy a jet kit to get your carbs jetted correctly. www.z1enterprises.com sells probably about all the jets available, should be able to find what you need there. Jet kits are way overpriced because there are enough people out there who believe that just because it says "stage 2" or "stage 3" they are getting better jetting and therefore more performance than if they take the time to do the research and determine what jets they need to install in their carbs. Figure out what jets you need and order the individual jets and you'll be right where you need to be.

I drill my jets all the time. I even drill out pilot jets down to #34. It's super easy since the hole is already drilled for the most part. You're really just reaming out a tiny bit. The holes are just straight through, there are no profiles or anything. The jet numbers are simply hundredths of millimeters. Don't let anyone tell you different, all you need to do is measure them and it's obvious. It's simple math to convert to thousandths of an inch.

The jet sizes I need are not available for the TK carbs, but even if they are, I would drill them anyway. I have many spares since the rebuild kits all come with the smallest size as standard.

All you need are some hobby drill bits which are tiny, and a cheap drill from Menards. The cheap "Tool Shop" drill has a chuck that closes all the way down. That is hard to find in expensive drills.

I mount the drill in a vise very lightly and use the excellect speed control on the drill. It can go as slow as 2 or 3 revolutions per second. That really helps. Then I just hold the jet in my fingers. It drills through in one or two seconds. If you want one size bigger, just let the drill run for a couple seconds.

I used to put the jet in a piece of flexible tubing to hold it, but then just got lazy and hold them in my fingers. It's not rocket science, it's just a hole in some brass.

I always check my mixture on an EGA and it's always very stable.

Agree w/ani, there's more to a jet than it's hole dia. and depending on application has different flow charactaristics. jet drills come in minute size differences, often still greater than oe changes.drilling is best opt when options needed simply aren't offered. the area leading to orifice and following, are usually chamfered, and follow the venturi/bernelli principals. after market jets seldom follow the same rules as oe, thus sizes from say Dynajet or flow master differ from oe.some jet are sized by dia. others by flow rate. Keep your' random variables to a minimum. best results are usually within the scope of oe.and seldom exeed a couple sizes without major engine mods, my 2 cents G

$10 for a pack of four jets. What exactly are we talking about here? :ohmy: The postage is half the cost of the jets.

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When you drill the jet, the chamfers don't get removed. Only a shaving is removed. I'm not saying to take a #20 jet and make it into a #200 jet. We're talking about #32 into a #34 or #37. That is .o2 or .05 mm removed from the ID.

Everytime I've drilled one, the bike ran much better. So if I'm altering the flow characteristic, then it's for the better. I've run a bike with Dynojet #98 mains and compared it to some #94 mains I've drilled to #99. There was virtually no difference at all in the bike's operation. At least none that I could tell.

But if someone has a source for #37 pilots for a TK-22 carb, I'd be willing to try them and put the bike on an EGA and compare the difference, if any.

The only jets I've seen on KZ's that I wouldn't drill are some of the 650 pilots. They are super tiny. I have yet to see a drill kit that size.

I drilled the jets two diff. times for my 1015cc motor. I have a set in it now and it's smokin. It works fine but be very careful not to over size them. One size bigger bit may be way too big for your motor. Like said above there are big jumps between bits and if it doesn't fall in the right place for your size increase it's gona be too much. Especially since your jets are probly close already. I had some 120's and drilled them with the smallest bit in an american set that was bigger then the hole and they turned out 155! So watch out. What you'll need is a bit that is barely, and I mean barely bigger than your jet, that might mean finding a metric bit. If the bit doesn't almost fit in the hole already it's gonna be too big. If you can't find a bit size as mentioned, you'll have to buy some jets. GO for it! Do it! What have you got to lose? 5 bucks? ten? Taking the carbs off twice. Hey maybe you'll break something else in the process! lol.:woohoo: