Carburetor jetting trick [YOU NEED TO KNOW THIS!]

[@NutsNBolts24]

My dad was a WWII aircraft mechanic, I learned this from him. Use to do it all the time on 70's cars as a teen/20'ish age. Great money saver and if you are willing to try a bit at a time and try it out it works good. And like the man said if you open it up too much a bit of solder and go back down a size.

[@RollingWrench]

You know what’s up :-)

[@Errol.C-nz]

There is a better trick to jetting down.. a lot of jets (most) have a necked down inner section.. like a venturi.. I have some pin punches with ends ground to about a 20deg very blunt angle & polished point.. slip fits inside the jet body.. punch the jet orifice swages the jet bore down .. careful weighted stiles with a small hammer can get very consistent results for multi carb settings

[@kennyh5083]

@@RollingWrench The right way is to buy 2 jets, and use one to determine the correct size, and once you've gone too far, then drill the second jet to the size that made it run best and leave it at that! Then if you ever do mods that require a bigger jet simply install the jet you over-drilled slightly and go from there! If the solder ever comes loose and goes into the engine you could damage a piston!

[@caduceus33]

I especially like the info on cutting off a tiny bit of solder and heating the jet, as well as chucking the jet and using running it onto the drill bit! Thank you!

[@dangerouskoin4874]

If you travel a bit with your scoot, having additional sizes with you isn't a bad thing if you go up or down elevation enough. That said, very nice kit!

[@49684]

You are a ROCKET SCIENTIST, I love tricks of the trade of any industry. 😊💪👊

[@mancavecustoms13]

Great stuff my guy. Just about getting tired of finding the right needles! This is the next step. Keep it up.

[@wallycleaver1046]

Just to throw a "wrench in the fire" LOL, Twist drills do not make round holes. And, they often push metal rather than cutting it, if not maintained sharp. Have you never deburred a hole? Where did the burrs come from? Also, twist drills make holes bigger than their shank size. Round holes are made with reamers or are cast, possibly stamped in a die, as such. The jet orifice is not simply a hole size. If you use magnification, you will see that the jet is ramped both into and out of the restriction orifice, and the orifice wall is rounded, not flat. The reason is that these forms help to keep the fluid flow in a laminar, non-turbulent manner over a wide range of fluid speeds. Stepped orifice walls will introduce turbulence, often in a modal fashion related to fluid speed or the pressure difference between the orifice inlet and outlet. You've probably seen this effect with a garden hose nozzle, where at low pressure the outgoing stream is solid, but when the pressure is increased, an air pocket begins to appear at it's output. When the pressure is increased more, the solid stream begins to flail about wildly. Drilled jets often flow LESS at holes sizes larger than smaller sized properly formed orifices, when subjected to high flow rates. Precision, well formed, holes are seldom achieved with $3 tooling, unless you are not measuring, or not looking very closely. It is possible to use jet reamers and jet gauges to get much better precision when modifying jet orifices. Still, these may not flow as well as properly formed jets. But, there may be no alternative if a suitable source can't be obtained. OR you can just drill your jets an get Riding!

[@matthewmase3549]

this is literally why i was scrolling through the comments. looking for the guy that knows what fucked up shit could come with just drilling a jet and sending it. thanks for your knowledge man. have a great day

[@thomasclerke4725]

Yes, that's something my father told me long ago. The entrance and exit as well as the actual hole. You will ruin a jet with a bit. Just buy another Jet.

[@southpawfrmguam]

Drill it shut? I literally just took a few hits before you said that and my mind was blown . I was confused but at the same time I knew what you meant, lmao my bad it sounded better in my head. Gonna try drilling the jet on my dirt bike tomorrow 👍🏽

[@Sage-qd6tf]

Oh hey I’m about to smoke too! I know the feeling of when something makes so much sense and then you try and write it and it’s like what the fuck

[@cchaquies]

😂🤣👌🇺🇸🗽

[@poet99999]

yep been doing this forever. after i find the right size jet from drilling i just order that. probably over kill but i assume brass is stronger than the solder or that solder may not be all that great long term... idk but yup this is the way to go for sure

[@jamesh5937]

My mechanic told me a trick he used to do was place one piece of thin wire in the jet to make the hole smaller by micro meters… The thing is if you hand drill a hole that’s super measured and thing could mess up your supposed to be perfect hole….

[@pantherplatform]

That's a really good tip. I have a ton of mikuni and keihin carbs with all kinds of jets but never thought of soldering and drilling.

[@aidankilleen5889]

If you can keep track of what diameter your mystery jet is at, good for you, you may have saved some money. If not for the questionable surface finish from drilling like that, potentially making it out of round, or simply not needing a precisely sized jet, I'd be all for it as a machinist, but I'm just going to keep bringing back/trading jets I don't need. In the end, it's just another way of doing things.

[@speedfreak8200]

Drilling was done in the stone age

[@Maxumized]

Don’t be afraid my friend…it’s just a jet

[@theodavies8754]

Clock broaches are around 1° taper. Cutting broach is 5 sided, smoothing broach is slightly out of round with a roughed surface. Get some control in your experimenting with making a flow tank. Tip. You don't have to test flow with fuel, water will give a good idea of the flow rate. Record the time a given volume took to pass through. It's not rocket science. Those drills are 0.1mm increments which is a lot. Just remember π x r² for hole diameter and you are good to go. With the smoothing broach you can measure how far in it goes with a caliper for close enough, mark with a Sharpie where you want to be. Happy days. Diploma in horology and a '99 TC88 FXDL. I don't like the sound from EFi Harley but that's progress.

[@russellpinner2279]

after watching your video i sorted my carb issues so thankyou, you de man

[@HYBRIDBATTERYSHOP]

Thanks for sharing in that awesome video. I just picked up 4ea mountain sleds, and brain farted the first one by riding it without rejetting. It's toast now but was the ride of my life twin pipe 1998 arctic cat zr 600.

[@BenJKlar]

Want it. Need it. Gotta have it. Thanks for the build vids and helpful stuff like this.

[@holywoodyamaha22]

Thank you for posting this! I have 04 400ex with a aftermarket pipe. OEM Jetting Main 148 Pilot 38, the pipe calls for Main 158 Pilot 58 but no elevation chart to factor in. I have a few carb kits I can try this on. Elevation 1050ft

[@benfranklin935]

No no no sir lol don't change the pilot the pilot is idle only going up with the pilot will cause you a hassle I rebuilt mine and did the 416 and 11:1 piston stage 2 cam and I was listening to people in the forums so I went from the stock 38 pilot to a 42 with a 178 main and it ran so good except after it got good and hot it would shot off at idle and come to find out the bigger pilot was causing the stalling and shutting off the whole time even with the bigger bore and higher compression piston

[@speedfreak8200]

42 pilot 152 main

[@speedfreak8200]

@@benfranklin935 42 pilot you barely need the choke and won't be cold blooded. They have to pass emissions for the EPA so new they come too lean not the way honda would have wanted.... 178 Main WTF

[@michaellarcom]

I was just looking at a carburetor schematic for a 2001 Honda 400EX and I noticed something that I don't see anybody selling with these jet kits. If you look at the schematic for a Honda 400EX there's the number (38) JET, SLOW AIR (#110) they sell you pilot Jets for the air fuel mixture on a pilot jet circuit. They sell you a main jet. They may give you a needle or some needle shims which were only rich in it not lean it if you don't have an adjustable needle. But I don't see where they have this number 38. I never seen a car very quite like the one on the the 300 400 450 EXs I guess I'm just used to the older style carburetors but I would think if you're pulling more fuel through the system don't you need more of the slow air adjustment?

[@k-sell4065]

I used a 1/16 drill bit for my 212 predator engine

[@benjaminhunt808]

When are you getting more in stock

[@joshbrewer316]

honestly seems like more work then just swapping out. in the long run what you pay for that bit of sadder and gas for the torch is a constant purchase, but having them jets on hand is a one time buy. easy to just swap out.

[@RollingWrench]

In some cases ya your right. In my case I would have to carry aver $800 in jets for all the different carbs . So it’s a nice little backup to have in your tool box. The best part of jet drills is they are more precise than jets. Jets go in 3 step increments. Jet drills go by each size.

[@jameskenney5623]

If you drill out an original Jet and change the orifice size then the next guy will have no clue what you've done and you have just ruined the "system" The next guy/shop thinks he's got a 78, but he's really got an 82..84..86 and is banging his head against the wall because it won't run. ultimately, it's because you couldn't spend a dollar on the correct jet size. Great tip!

[@quinnymandude1234]

be careful of some of these drill bit sets, they can be completely mismatched and have multiple repeats of the same size in a box. Make sure you measure each drill bit with a mic before attempting, or make sure you didn't cheap out on drill bits. I got 4 of the same repeats for 3 different sizes. Luckily I had a #66 and a #70 but nothing else.

[@jamesh5937]

I am fine tuning my carb and the kit came with 110 115 main jet… I need a 113 estimate because 110 is to small “I’m hitting my rev-limiter to soon” and 115 is to big “I’m bogging and seeing gas (white smoke) come out of my exhaust pipe”….

[@d.l.horton2093]

"Drill it shut." Great final words.

[@RulgertGhostalker]

SOL if your doing a 40mm Keihin, with that kit ... some torch tip cleaning sets are an affordable solution also, being by the time i overshoot a jet, i know where i am at enough to buy one.

[@dabertspracklin3086]

It would be great to have a visual while you explain the items you're talking about. Words and explain things confusing, visual is easy for most people to understand the situation

[@RollingWrench]

Noted

[@enoz.j3506]

I thought the new Ethonol fuel E10 etc,eats lead solder, and as its softer than brass,isnt that an issue?

[@bradfaught1695]

This is a old hand trick used by carb tuners everywhere, if your not familiar with it or think it's a hack-job....then your probably a rookie.

[@RollingWrench]

True story.

[@aidankilleen5889]

That's entirely your opinion. It's just another way to do things.

[@nunya9555]

​@@aidankilleen5889, don't get facts and opinions mixed up. The fact is that jets come in sizes of 3 and drills can go each step. Which would you rather have, sloppy but close, or perfect? Drilling is as perfect as we can get in the world of "Controlled leaks", otherwise known as carburetion. The OP is correct, rookie.

[@rynnff4648]

I just found out about this lol

[@Dirt_Serpent]

For people doing jetting on dirtbikes and traveling to different elevations exploring different places to ride it simply just makes way more sense to carry multiple jets. This is great if you’re only riding your bike in one place and never leaving but sometimes you need to change something out on the fly in mountains and this doesn’t work for that. Jets come in sizes of three because they are based on the basic need between every thousand feet of elevation. The fuel screw handles the fine tuning in between

[@emilkling7850]

but why don't you buy a metric dill set? then you don't have to guess the sizes. it corresponds to the drill 75 jet = 0,75mm

[@willistjohnson2543]

My carburetor is running great but every hour or so it fouls the plug I was told to make my main jet smaller . can I Sutter it close and start with the next smaller bit size that is smaller then my original jet I’ve been dealing with this issue for about 5 years now. Just been popping in a new plugs Waisting time money and fun

[@Mr.EeToMyself]

Just wondering if ya ever solved it?

[@SpoonerTuner]

thanks! the solder tick is a great idea

[@MJ-gq9nv]

All I'm going to say is Yes good idea but one must not assume drilled orifice will flow = 2 bought exact size because of flow bore length , good tune tip though to get it in Park 🤫

[@RollingWrench]

You can dial it in much better then jets. Jets go up 2 sizes at a time. Drill one step at at time. It’s more precise.

[@operatorgaming1669]

does homie not know they have jet kits that are made for the specific bike/ other application?

[@BillEddie]

Thank god you are willing to work on any scooter instead of being weirdly prejudice against Chinese scooters

[@mrcleanisin]

When the pilot jet is plugged up, just use a wire brush wire to go thru it.

[@RollingWrench]

Exactly 👌

[@ronbrideau8902]

Might have found a couple old jets for basic generator type motor in trail bike that could use upgrade. Solder sounds great but I might just put a 1mm hole a .5 mm solder coating over the larger than ~1.5mm existing jet hole. Think there is chance it may even work better with greater spray cone than simple linear jet. Thx

[@Bill-nm9wb]

Isn't the inside of the jet tapered to match the needle? So won't the solder trick undo that?

[@ujmrider]

This may work ok for single cylinder bikes. Drilling by hand for multiple carbs would be begging for trouble.

[@nunya9555]

Drills are a single step while jets skip around in sizes of 3. Wouldn't you rather get it perfect? Drilling is the closest of the two ways.

[@kobiisrael10]

I have a problem with this tool, it's a KTM 250 2T The tool has not been used for almost a year This week I found time to take care of it, I did a fuel-oil change, I cleaned the filter plug, everything, finally I tried to start it, but the car could not start. It only started with carburetor spray and shut off straight away From that I understood that the carburetor needed to be cleaned and that's how I did it. Now the problem is different, the motorcycle drives straight up to very, very high turns I played with the air-fuel screw but unfortunately it didn't help. Is there a situation where the problem is different? Something in the carburetor maybe? need help please

[@frez777]

that is one helpful piece of knowledge to know there buddy

[@noncompliant209cali]

Learned the hard way that all jets are different, I just bought a real Mikuni VM22 and tried buy jet kit. Was able to find main jets but all pilot jet kits are for the knockoff vm22. I never tuned a carburetor so don't know what size I need so wanted a kit with multiple sizes but can only find pilot jets for mikuni sold separately so trying to figure out what sizes I need for my Vader 125

[@ernestmurphy3898]

Awesome advice the predator 212 engine on the generator runs rich it comes with a 76 i think and folks buy a 68 and it seems to work would the tube that the jet holds in the carb need resizing as well?

[@Ethan.s..]

The tube would not need resizing. It will hold any size jet of that style jet.

[@jkreviea]

Lol, "solder to drill it shut."

[@oldman8141]

I just bought a gl1100 converted to one carb, it Boggs, I hope this helps

[@kilnmaster]

I live in the Philippines and have a Yamaha YTX 125. I want to put on a different muffler, here they call them a "chicken pipe". Is it mandatory I rejet? Or can I just get a "tune up"? Do all exhaust modifications require re jetting?

[@bmxkelowna]

New to tuning carbs and looking at rejetting my Honda spree after doing a full exhaust how will I know when I have the right size jet and how will I know if it's too large?

[@arthurcutaiar9994]

Great 8nfo,if your working on steam locomotive built before 1848. Jets are precision made. Glad i work on my own crap and don't pay people to screw my shit up

[@RollingWrench]

Works great with a nice set of precision drill bits :-)

[@stevebrzosko9793]

Nice - VERY informative! Thank you.

[@RollingWrench]

Glad it was helpful!

[@Diese1505]

Do you know how to tune a thunder jet super g carb s&s from zippers. It's a pain in the ass 🤔🤬 its on a 117 s&s 5000 elevation

[@mshadow64]

been doing this since before the 80s hehe it works fine! :)

[@RollingWrench]

You know what’s up

[@mshadow64]

@@RollingWrench yes! sure do :)

[@bendeleckeiii4229]

Omg u can also buy same drill bit set @ your local welding supply store. Called torch tip drills for $20. My little secret

[@RollingWrench]

Or a hobby store has them as well. You choose

[@ArthurSperotto]

Can you make this for cars as well?? I would love to use this this on my Holley 850 instead of paying Holley $10/jet!

[@josen.santos8959]

You are the best... Money saver

[@JEHERETIC]

Dude my dirt bike is a nightmare I have done 200 different jet scenarios and the God damn f****** thing just still does not run right it's sputters/hesitates really bad at about half to full throttle on acceleration

[@RollingWrench]

Do a compression test and check the valves. Also recommend a wide band 02 sensor so there is no guessing involved in tuning: www.rollingwrenchdenver.com/products/wide-band-o2-sensor-tuning-kit

[@flow_922]

I have a 2001 Honda vtr1000 carbureted it pops a lot when you let off the throttle jetting issue? Or is it normal for those v-twins to pop like that?

[@israelduffy9140]

I have a 274cc engine for my Coleman and can’t figure out what jet number to put in the engine

[@Kevin-j9c1l]

Just get the pilot jet, main jet for your carburetor 🙂

[@Survive2022]

So, is it effective putting a 150cc carb after a 50cc big bore swap?

[@cemtkeenan2750]

Did you find an answer? Im preparing to install a 47mm cylinder and head and need same info.

[@littlejoey4756]

THats pretty tight...good idea.

[@Alexclk230]

Hello, what sizes are the drills, please?So I can figure how to enlarge the hole. Thank you.

[@k-sell4065]

I used a 1/16 drill bit for my 212 predator engine

[@ernestmurphy3898]

@@k-sell4065 are you at sea level?

[@k-sell4065]

@@ernestmurphy3898 yes

[@jerrybigrig9475]

I went to my welding supply store bought a torch cleaning tip kit...drill bit style .. Good luck...

[@andyproctor3588]

I don't know if you have time to get back with me but I do have a question is it worth ncy direct coil on my GY6 150 I have and oml coil just asking getting tired of spending money on BS if you can get back with me just with a yes or no it will tell me everything waving my hand from Gainesville Florida

[@jameswilson2423]

Cool I'm definitely getting that from my. KLX 300r

[@brianlowe172]

I have a 2 generac GP3000i that I need a high altitude kit for but Generac does not make a kit for these so is there a aftermarket kit for these generators? They are 149cc motors

[@wilmer2754]

Hi I would like to buy a twin Plug & Play EFI kit for my Vulcan 500cc 1994. Do you know anywhere I can buy this kit. Many Thanks

[@carter.coleman]

I have a sportsman 700 with a big gun exhaust and idfk what to jet it to

[@jerrybigrig9475]

How about shimming up the midrange needle jet...???

[@jimambonekeener8081]

I bought a jet kit but the main jets are to fat to change mine are small round. How do I get the small rounded jets? Because these are new but I can’t use them. . My main is 76 I want to go to a 80 or 82 to help it idle and run better it’s running just a little too lean. I get air fuel adjustment right and it just doesn’t idle smooth it is ether to fast or Boggs down and dies I don’t have a way to check rpms so I turn adjustable screw out to make it smooth but then it runs to rich and it’s a brand new carb but it’s not jetted right.

[@ruben4927]

Love this video man. Well done

[@edwardseaton4492]

I could see myself ending up with a pile of jets that aren't what the numbers on the side of them say they are. I'd need to come up with an entire system of organizing them. I'd consider this route if I had a business. Otherwise though...

[@RollingWrench]

It’s important to grind the number off for sure. Only use the one jet. If you go to big solder it shut and start over. The main point is you don’t need a bunch of jets. Just one :-)

[@Bigredkarl]

Well deserved upvote

[@JEHERETIC]

Is there a Jet Drill kit for Dirt Bikes?

[@RollingWrench]

It will work for any carburetors

[@vickaminski]

Where can i get it and how do the hole sizes correspond to jet sizes? I have not a scooter but a yamaha banshee with pilot jets and main jets. So what size drill would get a 290 jet for example, is there a guide for that?

[@jondoe8816]

I was led to believe that drilling is not really a good way to enlarge a jet as the taper in the jet is not right for the size hole. But it was the 70’s when I was taught that

[@RollingWrench]

You are only going up micro sizes. You won’t loose the tapper

[@Brian-jz1pi]

​@@RollingWrenchI lost half the taper when drilling a 28 mm mikuni on a kz 1000.The bottom end was a little rich and I think I lost some flow characteristics in the top end range.I also remember the pin highth was a bugger to set.Never thought of adjusting the accelerator pump to come in later to help the lean spot.Its touchy I do remember that.

[@RollingWrench]

@@Brian-jz1pi you can use a larger drill bit to tapper the hole

[@lassassin2239]

Yeah I'm not drilling Bru that's actually wild af

[@robertstiles5122]

i like that drill kit how much

[@MotorheadRedo]

What Chinese 150cc scooter do you recommend? Are there any big Chinese scooters over 150cc? I saw another video of yours about the best quality Chinese scooter, but it was a 50cc model and the video is 7 years old. Thanks.....

[@dedeabsrn8044]

Automatic choke does not activate in cold engine. What is the reason? How do I set it.?

[@scmafia7515]

What if you needed say a 150, I didn't see a 1.5 in your kit.

[@user-neo71665]

As a mechanic, buy a jet kit for $6 on ebay. Do not hack crap by drilling jets. Gas and fuel additives are corrosive and react with lead over time. Remember back in the day when lead was dissolved in gasoline to prevent knocking on high compression engines?

[@RollingWrench]

I have been doing this for probably 15 years. Never had a negative experience. No hack here, just a simple hole being drilled. If your worried you can buy a $6 jet from eBay if you go to big, so solder isn’t used. No more buying jets if you have drills. This isn’t for everyone, it it works great for me though.

[@stephenscr]

TEL is produced by reacting chloroethane with a sodium�lead alloy.[8] 4 NaPb + 4 CH3CH2Cl → (CH3CH2)4Pb + 4 NaCl + 3 Pb The product is recovered by steam distillation, leaving a sludge of lead and sodium chloride. TEL is a viscous colorless liquid. So no the lead won't dissolve.

[@SethZooms]

How does the bike act when you have a main jet too big

[@RollingWrench]

Sputter

[@SG-wv7qu]

I have a 300cc icebear zodiac trike. When I went to put it into forward from neutral I pulled it too hard and now it wont go into forward neutral or reverse. Can someone plz tell me what to do next or where to go I stay in Maryland

[@erickittrel]

I have a old taotao scooter that was a gift and would like for you to restore it

[@jameswilson2423]

I searched tuning 4-stroke dirt bikes for elevation because I realized I lived in the city and I go way up in the mountains in my bike runs like crap and I'm a squid

[@topnotcharms1]

Did not see it on your website?

[@jdog4534]

Nice kit. But what about the other jet? ..the teeny tiny one? You can do the same thing but the tiny micron sized drill bits are hard to find. You can find them at welding supply houses. They sell them as torch tip cleaners but that little pin vise (not hand drill) might be too large to chuck up the bits. You'll need the smaller pin vise, or try bushing up the drill bits by wrapping it with fine speaker wire or welding lead wire. ..don't forget to lift the seat in the bowl if needed. Edit: I've heard about soldering up oversized orifices but I always wondered about the operating heat of the engine. Will it get hot enough to melt the solder? I brazed the one closed on my water heater, just in case. ...actually, isn't it welding if you're doing it to brass? 🤔😏

[@scottalanclymer]

Does fuel flow erode the lead afterwards? That would be my question.

[@samuelpanasyuk2955]

Can you do it to the pilot jet?

[@hvhnubek]

i have a 200cc shineray dual sport,im at 2800ft elevation and im wondering if the 115 jet is good,stock is 102 and it bogs when u throttle it and overheats

[@hvhnubek]

would that be a good jet for it? @Rolling Wrench

[@nunya9555]

Doubtful that it needs a larger size than stock. Take a spark plug reading and see what color it is. Google that process. If the plug is black, it is too rich. Whitish equals too lean. You want a slight brown color. Your bike probably doesn't need tuning. More than likely it needs a carb clean.

[@49684]

Your a ROCKSTAR

[@GordinJ]

Bad idea. For next time you will never know what size hole you did. And nobody in the entire universe will either. Jets are numbered. So next person may know what you did. This is one of those mechanics I don't recommend going to.

[@AaronRiegel]

Good video. Quick and succinct

[@tubejim101]

Great idea

[@bigsweden1975]

What would be suitable jet sizes of 90cc GY6. Pilot and main. Thanks

[@edsontototan5894]

Where can I buy the drill Beat for the said jet?

[@ironhead320]

What size screws for the carb bowl

[@stasysstrauka9818]

hello guys can anyone tell me what is the point of a carburettor trick? 😮 why do you need to drill a bigger hole? does it give more power at higher rpm? and its trick works with all engines that have carburetor?

[@RollingWrench]

It’s to add more fuel if needed. You want your carburetor to have the perfect fuel mixture. This is achieved by jetting the carburetor.

[@jacobtucker6819]

I have icebear maddog clone like to know what size the engine is and more

[@nicholasventura4107]

When are you going to get some in

[@RollingWrench]

Maybe 3 week or so

[@rasmushjs5318]

What about the pilot jet ???

[@RollingWrench]

Only works for main jets :-(

[@jamesmason7124]

Hello from the high desert of New Mexico USA 🇺🇸 about 6000 feet. What size of main jet would you recommend for a Predator 3500 inverter generator? Thank you and please stay safe

[@RollingWrench]

Take the jet size that’s in it and times (x) it by 0.92 (your atmospheric pressure) that will give you an idea of the sea level to 6000 jet to start with

[@jamesmason7124]

@@RollingWrench thank you