is there a good drill bit set that realates to jet sizes??

[sr5bidder]

While not using this info for my kdx as jets are avalible,, I was wondering if anyone had any info to share on micro sized drill bits (must be good quality as if it breaks I'm screwed.

I haven't looked real hard but at a glance the jets for my xt350 are hard to come by and since I'm going bigger (4stroke!!) on the sizes I think I can drill em out a little at a time with the right tools??

any help would be great as these bike are meltdown lean from the factory and I put a new piston/rings in.

 

[julien_d]

No such thing that I've ever ran across, and it'd be wicked easy to destroy a brass jet.

Is that a mikuni carb? I bet jetsrus has what you need. Great guys to deal with too. I have a few old mikuni jets laying around here. Probably nothing big enough for you though, other than maybe a 42 pilot jet. There's an old buddy of mine near here that has a bike shop. He has an entire wall of small drawers with jets of all kinds. I'd just about bet a paycheck he's got what u need if you can't find it at jetsrus.

J.

 

[whenfoxforks-ruled]

Example: A number 45 drill bit diameter MAY coincidentally match the bore of a #45 jet. BUT, it will NEVER flow the same. Jets are a machined hole, by a broach or a ream. A drilled hole is too coarse. There are all kinds of resources for jets. If Sudco does not carry it, you probably do not need it? http://www.sudco.com/

 

[digifox]

Uh, Jets HERE are ONLY $2 Ea.
Buy a few in Diff sizes and Tada.

 

[sr5bidder]

nope, I will take that paycheck ,it's a Teikei 2 barrel vaccum secondary rumor has it that kiehin jets work for the mains but can't use the anti sloshcup..... pilot is not out there.. that I have found...I will check your sugestions though. thanks

 

[julien_d]

I'll ask my buddy about the Teikei. He's really big on older stuff, so there's a good chance he either has the pieces or knows where to source them. I mean, the guy had two gas tanks in the shop for my 1973 kawi 250! He's pretty impressive....

J.

 

[sr5bidder]

ok but everone over at thumpertalk says they have to drill the pilot out or use minkuni vm28/486 pilots

 

[dmerc]

I redrilled the main on my KDX. Soldered the end closed, then redrilled at .0595",as I recall? Which is a 152 mj size.

152 main, equals 1.52mm, equals .05984

The bits came from a set of tiny ass drill bits from Harbor Freight. It had many sizes, and were in a blister type packaging. Scads of the little buggers, varying in size, but all small, as in jet sizes.
Just gotta' measure carefully with micrometers, till you find the closest match.

 

[mideastrider]

Wire guage size drill bits is what your looking for. They come in sizes 1 thur 80. They range from about .013" thru .228" .

 

[julien_d]

ok but everone over at thumpertalk says they have to drill the pilot out or use minkuni vm28/486 pilots

And they might be right. I'd be relucatant do drill the only set of jets I have though! What's wrong with using the mikuni pilots? Is there some headache involved? Any mikuni jets should be relatively easy to find.

 

[whenfoxforks-ruled]

That is a "herman" carb all right! Yamaha ran them on their 65 tt600, now a 2 barrel? http://www.carbkit.net/TEIKEICARBURETOR.asp . If all else fails, find what available jets have the same thread, just keihn? Why no pilot jets? Won't mikuni jets fit? And for the second time mideastrider, drilled jets DO NOT FLOW THE SAME! Any 2 drilled with the same drill bit, WILL NOT FLOW THE SAME. ESPECIALLY SOME CRAPPY DRILL BITS FROM HARBOR FREIGHT!!! Buying the proper tooling is ridiculous to be attempting this in the garage, if available at all? They are more than likely hand made tooling.

 

[adam728]

That is a "herman" carb all right! Yamaha ran them on their 65 tt600, now a 2 barrel? http://www.carbkit.net/TEIKEICARBURETOR.asp . If all else fails, find what available jets have the same thread, just keihn? Why no pilot jets? Won't mikuni jets fit? And for the second time mideastrider, drilled jets DO NOT FLOW THE SAME! Any 2 drilled with the same drill bit, WILL NOT FLOW THE SAME. ESPECIALLY SOME CRAPPY DRILL BITS FROM HARBOR FREIGHT!!! Buying the proper tooling is ridiculous to be attempting this in the garage, if available at all? They are more than likely hand made tooling.

He's completely right. Jets are machined, then flowed. I've made jets at work before using a mini lathe and high quality drill bits. If I made 50 jets I might get 35 pcs that flow in the desired band, 5 pcs under, and 10 pcs over. You simply are not going to get the accuracy you need using something like a cordless drill and cheapo bits.

Even quality jets that are flowed usually are +/- 2.5%.

 

[dmerc]

........... And for the second time mideastrider, drilled jets DO NOT FLOW THE SAME! Any 2 drilled with the same drill bit, WILL NOT FLOW THE SAME. ESPECIALLY SOME CRAPPY DRILL BITS FROM HARBOR FREIGHT!!! Buying the proper tooling is ridiculous to be attempting this in the garage, if available at all? They are more than likely hand made tooling.

That is the biggest load of crap, no matter HOW many want to agree with you. It's total BS! :coocoo:

>>>>>"ESPECIALLY SOME CRAPPY DRILL BITS FROM HARBOR FREIGHT!!!" :laugh:

Drills are drills, they either cut to size, or don't...this isn't titanium being drilled here!!


>>>>"They are more than likely hand made tooling." :blah:

BTW, I HAVE a minilathe.....actually a "crappy Harbor freight" mini lathe. But, I drilled my jet with a cordless drill!! :rotfl:

Flame away, but you're wrong! :nener: Accurate hole sizing is ALL that matters

 

[whenfoxforks-ruled]

Flame, no, fact. And further proof fools with tools are everywhere? Odd thing is it comes out of kdx riders as much as anywhere? Call Fredette and ask him. Would you believe him over some drugged up guy figuring? How much machine shop experience do you have? Adam 78 knows and then some!

 

[Rich Rohrich]

Flame away, but you're wrong! :nener: Accurate hole sizing is ALL that matters

You should have paid closer attention in Physics class genius. You couldn't be more wrong if you tried.

:coocoo:

 

[whenfoxforks-ruled]

I was just pointing out the physical reason its wrong. The physics part is a lot worse! The only thing accurate at harbor freight is the loss of your money for crap tools made by little Chinese kids. My cheap #1 son learned the hard way also. Its worth scrap metal prices at best.

 

[julien_d]

Flame away, but you're wrong! Accurate hole sizing is ALL that matters

We're talking about your jets and bikes, not your girls ;) . Just making sure we're clear on that.



Sorry, I could not resist......

 

[dmerc]

Okay ladies, let's see this "special tool" for sizing jets.

Total bull....all of it.

Just because you've all listened to the same crap, doesn't make it true. It only makes you wrong, and gullible. :nod:

As for Harbor Freight, they have cheap tools, for when "close" is good enough.

If y'all wanted brain surgery, I'd be a bit more selective. :laugh:

 

[_JOE_]

Okay ladies, let's see this "special tool" for sizing jets.

Total bull....all of it.

Just because you've all listened to the same crap, doesn't make it true. It only makes you wrong, and gullible. :nod:

As for Harbor Freight, they have cheap tools, for when "close" is good enough.

If y'all wanted brain surgery, I'd be a bit more selective. :laugh:

You must be an engineer! I take it you work for Chrysler? :rotfl:

Sometimes in life you're better off to be quiet and learn the proper way to do something. If you feel like "close enough" is good enough for you, feel free to modify your stuff how ever you like. What these KNOWLEDGEABLE guys are trying to tell you is FACT. The finish of the surface has an effect on flow.

 

[sr5bidder]

new question

Whoa..been putting a mini trail engine together all weekend and drinking beer.... looks pretty heated in this topic.

So when I find a jet with the right threads can I assume that jet sizes from different carb makers are the same or do they size them thier own way??

 

[whenfoxforks-ruled]

Whoa..been putting a mini trail engine together all weekend and drinking beer.... looks pretty heated in this topic.

So when I find a jet with the right threads can I assume that jet sizes from different carb makers are the same or do they size them thier own way??[/QUIf the thread pitch is the same, and the length of the jet, you are in business.

 

[Rich Rohrich]

So when I find a jet with the right threads can I assume that jet sizes from different carb makers are the same or do they size them thier own way??

You're probably OK from the standpoint of a jet bolting in place but there is a bit more to it.

Mikuni hex head jets are numbered by bulk flow, while Mikuni round head jets and Keihn jets are numbered by inner diameter in mm.

The flow difference between a Mikuni 175 hex jet and a 180 is about 6cc ~3%) . Keihn jets are numbered by jet id, and the difference between a 178 and a 180 is about .0008" (I'll let those so inclined do the math to determine the flow difference) .

Now to further confuse the issue keep in mind that air/fuel ratio is based on weight of fuel and weight of air, but jets essentially meter by volume. So we really need to know the weight of the fuel flowing through a jet to understand all this. In simplest terms fuel weight is a function of the area of the jet multiplied by the value of the square root of the fuel head pressure multiplied by the density of the fuel.

It looks like this:
weight of fuel = jet area * ( SQR Root (head pressure * fuel density)

The sad fact is the cross sectional area of two properly made jets marked with the same number can vary FAR MORE than the difference in flow due to small changes in density . Good jets can vary as much as 2-5% cheap jets can be closer to 10% variance, and jets drilled by hand with a junk drill bit set will be about as consistent as a potato with a pencil hole punched in it.

I hope this helps.

 

[whenfoxforks-ruled]

That is the biggest load of crap, no matter HOW many want to agree with you. It's total BS! :coocoo:

>>>>>"ESPECIALLY SOME CRAPPY DRILL BITS FROM HARBOR FREIGHT!!!" :laugh:

Drills are drills, they either cut to size, or don't...this isn't titanium being drilled here!!


>>>>"They are more than likely hand made tooling." :blah:

BTW, I HAVE a minilathe.....actually a "crappy Harbor freight" mini lathe. But, I drilled my jet with a cordless drill!! :rotfl:

Flame away, but you're wrong! :nener: Accurate hole sizing is ALL that matters

Regrettably I know a guy who bought one of them also. Accurate, no. I would rather have a 100 year old used south bend lathe any day. And do not loose your receipt! Its good for 30 days. Real world, an .018 bit can drill a hole about .020 or bigger, its called clearance. Then you go in with a ream or broach to take the last couple of thousandths off the finish bore. Harbour freight does not sell those, they only sell you enough to get you in trouble, think you know what you are doing, and coming back more for more! This is nothing, its dirt bikes, you should see what self proclaimed geniuses do for plumbing repairs! When harbour freight opened, the cheap in me sent me there, I do not even buy latex gloves there anymore!

 

[dmerc]

Sometimes in life you're better off to be quiet and learn the proper way to do something. .

Do a search on drilling jets. It's commonly done, even by race team mechanics. Cars/trucks/bikes/

If the tiny variation caused by surface finish is so worrisome to you, remind yourself, it's a bike, not a nuclear reactor :laugh:

 

[dmerc]

Regrettably I know a guy who bought one of them also. Accurate, no. I would rather have a 100 year old used south bend lathe any day. And do not loose your receipt! Its good for 30 days. Real world, an .018 bit can drill a hole about .020 or bigger, its called clearance. Then you go in with a ream or broach to take the last couple of thousandths off the finish bore. Harbour freight does not sell those, they only sell you enough to get you in trouble, think you know what you are doing, and coming back more for more! This is nothing, its dirt bikes, you should see what self proclaimed geniuses do for plumbing repairs! When harbour freight opened, the cheap in me sent me there, I do not even buy latex gloves there anymore!

Well congrats, and who cares? Now you need to attack Harbor Freight to feel superior?

I don't give a rat's ass about HF, OR, your opinion. I'll readily admit that BOTH are crap! :rotfl: