Oversized (80+) jets, where or how?

Discussion in 'Motorized Bicycle General Discussion' started by Frankenstein, Jun 25, 2016.

  1. Frankenstein

    Frankenstein New Member

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    So, installed Reed valve, and other mods, had to increase my jet sizes a few times, latest mod involved needing more than size 80. Looked and looked, nobody sells them past 80 unless it's foolishly expensive (5-8 bucks PER jet) to buy it.

    My method, use calipers to find a steel pin or needle of the appropriate diameter (79 jet is .79mm diameter hole. I like to press a micro drill bit of the Carbide variety against the pin perpendicularly with my fingers and turn the pin round and round untill a spiral groove is cut along the entire length, creating a pathway to remove material like a drill bit would, doesn't have to be deep, just noticeably there. The first 5-10mm from the point I rub a diamond grinding bit along it to rough it up a little, helps make it a bit more abrasive. Fasten the jet in a drill chuck one way or another, just not via the threads, a good way is to use a stock carb with the long brass rod that holds the jet. Run the drill, and slowly drive the pin in place.

    Now you've got a custom sized jet. Works with any pin far as I can tell. Currently experimenting with drilling multiple micro holes in a closed jet, and adding up the surface areas of the holes to make a specific jet size. The multiple holes can atomize the fluid better than one large hole. Think about carbs with multiple jets per intake.

    Whatcha think? Easier way to do this? It a bit of a pain to sort through jars of pins but the end result is always beautiful (and cheaper by a long, long shot.)

    Also contemplating a way to stuff my crankcase with jb weld so that the chances of losing bits of epoxy being virtually eliminated. I'm looking as using some micro bits to cut holes, tap them to a 1.3mm thread, then locktight a few micro sized screws into said holes, and those will be the anchor to the jb weld, it would be next to impossible for the epoxy to fall off unless chiseled away. This method might not be for everyone, in fact it's not, you'll need a steady hand or a very small and precise drill pressing stand to make working threads. A little slop can be made up for with jb weld. Alternatively you can drill 2 small holes towards eachother at a 45 degree angle, and push pins into them, once jb weld cures around them they will be locked in place at the angle, locking the weld down too.

    Mongoose terrex, stock engine ported, Reed valve, piston to match, delorto clone, modified shift kit, and a gastank from a 1970s suzuki ts125. My expansion chamber is cut and welded in my backyard, might be less effective than it was stock, but works well, looks fine, sounds like i chopped the baffle off, which is what I did, but around here everyone and their brothers car sounds like they took their muffler off so no biggy. Also bike gives me headaches as often as it doesn't.
     
  2. Tony01

    Tony01 Active Member

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    Or.. You could just buy a drill set with every size for $20.. Even HF has a micro drill set for $4 but not many different sizes. Only thing is that these micro drills like to spin in excess of 15000 rpm, so whatever you got that spins fast use it.

    Also I wouldn't do all that drilling and tapping. It's a disposable motor anyway.
     
  3. 2door

    2door Moderator
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    Micro drills like to spin at 15K??????

    Strange. I use mine in a pin vice and rotate it with my fingers. Are you sure we're talking about the same thing?

    Tom
     
  4. Frankenstein

    Frankenstein New Member

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    Never heard of that 15k stuff, not unless we are talking cnc. I modified a cheapo drill and stole the chuck from it, set it up with some bits of left over shelf brackets, and put a nice 1 inch wheel on top. Turn the wheel and gravity does the rest. It's for very precise work, using special compounds to hold to item being drilled if needed. The mini press works great for anything larger than a quarter of a millimeter.

    I don't know what the point of looking as these things as being so disposable is supposed to do. I mean perhaps if your looking to fry some chrome then go ahead get nuts with it. My post/thread has nothing to do with burning metal with new metal as a backup, it's about the challenge of building a castle around the structure of a camping tent. I want to bring a motor from being weak and unruly to being powerful and capable under most conditions. I even rode my bike in the snow covered streets, during blizzards, in the rain, in the woods, and without an air filter, but you couldn't tell it ate salt water and pine needles unless I told you, and then you still wouldn't believe it.

    I think the challenge is the part worth working on, and the only thing I dispose of are the problems, being a cheap bastard helps too.
     
  5. Tony01

    Tony01 Active Member

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    Pin vices are good for cleaning burrs in holes with the right drill, but not for actually drilling. If you do you risk cutting a hole that's not straight, round, or to size. Also those drills are very easy to break. If you want a nice surface finish in the hole the best way is to use a drill press with a dremel attached and turn it up to the highest RPM and drill with multiple light pecks and some cutting oil or wd40. Actually micro tools like to run at up to 30k-ish. Parts like jets are made on Swiss screw machines which are similar to CNC lathes only they are somewhat smaller and have multiple axes, chucks, high pressure oil coolant systems that allow for drilling very long holes in very small parts accurately and quickly, usually live tooling on different sides - so the drill spins at let's stay 10k and the chuck spins at another 10k for a combined 20, etc. And their precision is much higher than lathes. So if you were to drill a jet bigger you'd need to go into the side holes with a pin vise and either a drill or sharp edged precision gauge pin to deburr, then go down the main jet and deburr, repeat until no burrs. A screw machine can cut over 30 jets a minute... I would just buy these jets as is and not mess around with drilling them..

    Also you won't be able to measure a small drill accurately enough with a caliper. The difference between jets is only .0004", my own measuring tolerance is around .0005" or so and that's on rectangular parts. Round parts? Forget it. Only thing that will work is a 1" micrometer that reads thousandths, tenths mics are the same only they also have a vernier scale on the side for the tenths.

    If your drill chuck isn't small enough to hold a tiny drill you can use a pin vise to hold it, but there are some steps. First off you must check the runout. With a small drill just hold a piece of white paper behind it and see if it runs out. If it does at all you'll have to stick it out very far and drill with it deflecting somewhat so that it "follows the hole". People do this frequently with reamers. Other thing is that a pin vise won't hold it too strongly like a micro chuck so you need to go slow.
     
    #5 Tony01, Jun 26, 2016
    Last edited: Jun 26, 2016
  6. Frankenstein

    Frankenstein New Member

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    20 dollars for every size micro bit in increments of 100ths of a millimeter? Please do share, all I find are sets with increments of 0.03-0.05, makes for difficult jet work when all I can make is 63 65 73 75 83 85 93 95 ect... I must be missing something or that something doesn't exsist formally at 20 dollars unless you have an additional 200 to throw towards it
     
    #6 Frankenstein, Jun 26, 2016
    Last edited: Jun 26, 2016
  7. 2door

    2door Moderator
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    That all might be correct but.....we're talking about opening up an orifice in a carburetor jet. We're not making watches. There is absolutely no need for the precision you're talking about to allow a little more fuel to pass through the jet of a simple Chinese carburetor.

    No need to complicate a simple operation that doesn't require the degree of precision you're describing.

    Tom
     
  8. Frankenstein

    Frankenstein New Member

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    I'm not complicating anything. Jets don't exactly exist readily after 80, some people need more than 80 to keep the engine running from running lean and all the crap that comes with it. So this is how you make it bigger, and I can do it in under 5 minutes exactly when I need to and while the bikes being tested I can cut 2 more, one a size larger and the other smaller.

    Me and my cheapo macbastardo friends have great running bikes, enjoy the art of drinking beer, and are happy. That's what happens when you get a welder, an expert on fasteners, a bearing chain and sprocket specialist, racing fuel technician, a watch builder's apprentice, old and new time mechanic, and a former dental reconstructionist and marine core engineer all together in a big group and toss in a few happy time motors.

    It's not about being complicated, it's about advancement. But I guess if we all had the "it's good enough" mentality then we'd still be stuck in the stone age with our brass wrist pin bushings, good thing using a roller bearing wasn't considered too complicated...
     
  9. YesImLDS

    YesImLDS Member

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    I don't think they are saying it won't work, just that it's more complicated than it should be. Micro bit and pin vise makes my bike run pretty well at 10k rpm...
     
  10. 2door

    2door Moderator
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    Cool down, Frank.
    My reply was to the other member who was advocating using advanced machining technique to drill out a jet orifice. Not you. Read the post above mine. # 5

    Tom
     
  11. Frankenstein

    Frankenstein New Member

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    Not sure if he was advocating an advance technique, I think he was explaining it. He even stated he'd rather buy them then make them.

    Is there a specific problem you guys have with sharing thoughts and solutions or promoting the advancement of current technology on this forum?
     
  12. 2door

    2door Moderator
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    On the contrary. The reason this forum was created was to help members have a running, reliable motorized bicycle. Many of them have limited mechanical knowledge or experience. We strive to offer help and advice, share thoughts and "advancements" in the hobby. Nevertheless we don't want to see a new builder overwhelmed with technical information that is out of his/her reach and be discouraged.

    When alternatives to a given and time tested procedure are offered it might be a good idea to explain that it isn't absolutely necessary and a simpler solution is available.

    If you want to continue this discussion I suggest you contact me via a PM.

    Tom
     
  13. Tony01

    Tony01 Active Member

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    just use a drill press. Hand drilling is fine for personal use, but then giving advice on jet size and how to hand drill it is just adding to the larger unwanted part of the Internet, garbage in garbage out. Nobody knows least of all the guy hand drilling what size it actually is.

    Here's a carbide set of numbered drills, these won't follow a hole as much as HSS and they'll bore it, need a drill press for these for sure but yeah got sizes bigger than what you need in jumps of .001 which is two jet sizes
    http://m.ebay.com/itm/161720379861?_trksid=p2141725.m3641.l6368

    agk
    http://www.affordablegokarts.com/Drilling Main Jets.php
     
  14. Frankenstein

    Frankenstein New Member

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    The first link is mostly useless, it increases mostly by .05mm, again that's not ideal for getting a custom 83 jet, or 87.
    Your second link is quite a bit more in line with the idea I already provided, cutting, measuring with a caliper ect...
    However the second link says "let's use drill bits!" which is not the point, I own the set in the first link, not effective in all cases, second link just proves I had a point.

    I don't even use pin vices! Stop mentioning it like it was part of the threads point. And of you look through an assortment of pins you'll find a pin with a diameter correspondening to a jet size, usually very quickly, once you get used to looking at it, then prep is easy and you can cut jets on the fly, even on the side of the road with nothing but said appropriate pin and a screw driver, it's just that easy.

    As far as less mechanically inclined folks go, don't be talking about defending their inabilities and then talk about pin vices and then defend members who are posting links describing exactly my so called advanced techniques, all in the same thread buddy.

    Anyone who's in need of an 80+ jet had to of done interpersonal modification of said motor just for it to require that jet! Jesus I think if they pulled that off they can use a needle, caliper, and a drill.

    Common sense people, it's free, use it.
     
    #14 Frankenstein, Jun 27, 2016
    Last edited: Jun 27, 2016
  15. ftw357

    ftw357 New Member

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    Depending what carborator you have I overcome this problem with a cns by using a nt mane needle it smaller in diameter at the point and let's Moore full in her no more bogging hi rpms hold on tite haaaaaaaaaa.duh.
     
  16. ftw357

    ftw357 New Member

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    Depending what carborator you have I overcome this problem with a cns by using a nt mane needle it smaller in diameter at the point and let's Moore full in her no more bogging hi rpms hold on tite haaaaaaaaaa.duh.
     
  17. ftw357

    ftw357 New Member

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    Depending what carborator you have I overcome this problem with a cns by using a nt mane needle it smaller in diameter at the point and let's Moore full in her no more bogging hi rpms hold on tite haaaaaaaaaa.duh.
     
  18. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Changing the carb needle will only affect the low to mid throttle response of a carb... When a carb is 'wide open throttle' the needle isn't affecting the fuel flow.

    'Wide open throttle' fuel flow is controlled by the main jet.
     
  19. ftw357

    ftw357 New Member

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    Have you achy dun this I have and it makes a big difference by mixing the are full oil together for better combustion I have Bilt two stoke ingens all my life and carberators are 1 of my spsheltys dnut
     

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