Carby Keihin carb clone

Discussion in '2-Stroke Engines' started by SRPM, Apr 20, 2016.

  1. SRPM

    SRPM Member

    I made a thread more vague about this so I'm making a new, more specific post.
    So I'm looking for anyone that has used one of these clones with any info they can provide. Mainly I'm looking for jets for it and like tunning advice for the dang thing. Here are a couple pics to show what it looks like and show what markings are on it.
     

    Attached Files:


  2. How is your bike running with that setup i have the same thing and my bike is boggy and slugish are you having the same results if so alot of people been telling me i need to do some porting because of the reed valve i also read somewhere that if you use the box reed valve and your not running a ported Cylinder that it restricts the fuel flow not really sure how accurate this info is but as far as tuning you may have yo adjust the c-clip position on the needle and there is an idle adjustment screw on the right side of the carb under your seat but if you do find some jets for this carb do let me know which is also still something we might have to do 20160429_161924.jpg 20160429_162018.jpg
     
  3. Also wanted to ask you about that little hose coming from the bottom you have it pluged in the side by the fuel intake at first thought thats what i thought i was supposed to do so i just let it hang but are you supposed yo plug it in the shaft by the fuel intake?
     
  4. SRPM

    SRPM Member

    Nice bike. I'm not having any real boging or being sluggish Im a little more and less than a mile above sea level and I'm not running the long poopoo pipe tho too. I have good power down low (when I'm taking off from a stop) just not much top end power or speed (27 average mph and it has trouble getting up smallish hills. I have heard these box reed valves suck and that the rse reed valve is way better.I have not heard anything about having to do porting, that could be true but I know yours and mine have ported cylinders. As far as the tubes, there is a fuel inlet(obviously) the other one on top is fuel bowl vent and the one on the bottom I have not figured out, if you take the fuel bowl off you can see the nipple on the outside leads in to a needley thing that seems the sit above the fuel level. I have adjusted the c-clip on needle up one and set the idle screw and idle air/fuel screw. I've done lots of research for jets and have found the right ones but they are $6-7 a piece. Here's what I found:
    Jet overall length: 7mm
    Jet head diameter: 5mm
    Jet thread diameter: 3.9mm my actual measurement was 3.87 mm
    Jet size measures .68mm
    So taking the jet measurements I found that the matching jets are from a Keihin 99101-116 carb or a Keihin N424-35 nickel plated, both are the same one is just nickel plated and are the same price. They are available on jetsrus.com.
    Here is the link to the jets:

    https://www.jetsrus.com/a_jets_by_c...hin_99101-116_main_round_small_and_38-xxx.htm
    See as they are so expensive and not knowing exactly what size jet I have I went and bought some solder and some micro drill bits from the hobby shop down the road and a rotary micro drill bit set from harbor freight. Bought the set to determine what bit size the jet was. Turns out its is a #72 sized bit from Excel Hobby Blades they are $8 for 12 bits of the same size (they do break easily) so maybe not cheaper but I know I can solder and re drill over and over and over again. I will be drilling to #74 and we'll see how that dose when it warms back up.
    When rejetting remember the reed valve tends to richen things up a little because the air moving through the carb then has to "wait" in the space behind the carb and before the reeds I'm not 100% on that but think about how the air is flowing. Here's a pic of what I did with my "tubes".
     

    Attached Files:

  5. SRPM

    SRPM Member

    Looks like you dont have the high comp. head on the engine too. Could be part of the boggy sluggishness.
     
  6. SRPM

    SRPM Member

  7. SRPM

    SRPM Member

    Sorry that I'm just remember this but it is really important that you make sure your spark plug is actually connected, mine was not and I had a very disappointing first start up and run. It could not rev up well at all and could have been boggy and sluggish but I never ride on my first start up its just a check for me to make sure everything is good and to start the break in process. All you have to do is under screw the little connector piece on top off the spark plug leaving the threads exposed (pic) and you'll have purrrfect connection. And this is with the supercharged CDI. 20160501_143056.jpg
     
  8. butre

    butre Well-Known Member

    that depends on your plug boot. I have to unscrew the nipple but many boots don't require that. also it's worth noting that many spark plugs don't have the option of unscrewing the nipple
     
    SRPM likes this.
  9. Do i need a compression head to run this setup
     
  10. SRPM

    SRPM Member

    I don't think so, I've heard they can be to much and can cause the plating from the cylinder walls to flake off. I just noticed it wasn't on yours and could be effecting the tuning.
     
  11. Ok so as far as idle what did you do cause mine either reved to high right around 3500-4000 or reved so low the bike would stall at times it would rev up to almost 7000 rpms and i would hit the kill switch to not cause harm the idle screw seems to do nothing and the air screw seems to do nothing as well
     
  12. SRPM

    SRPM Member

    I really didn't do anything at all. When I first started it kept trying to die so I turned up the idle screw (the biggest) and then screwed the smaller one in all the way in and screwed it out a quarter turn at a time and revving it up in between and letting it settle out to find the right idle. After I found the sweet spot I adjusted for the best take off because that is the starter jet as well(if i remember correctly). Check out that link and you'll have a better idea of how to set the smaller screw.
     
  13. SRPM

    SRPM Member

  14. So after reading that yes your right does help you understand a 2 stroke carb so after reading went to try adjusting it i know have the c-clip on its richest setting as well as the air screw turned all the way in which is also at its richest setting so after doing some research and watching a good video which was on a dirtbike but was same issues i was having which makes me think i need a richer pilot jet and possibly a richer main jet once i get the jets ill do pilot jet first to see if that fixes my problem but the reason i say main jet as well is vecause that controls from 3/4 to full throttle which is where it cuts out and feels like theres a speed restricting device in my engine but back to the pilot jet no matter how much i adjust the air screw and idle screw she wont idle if i rev she goes up down trys to bog and die then i have to rev again so my conclusion the pilot jet is running too lean and i need one a little bigger once that gets done then i can see where im at as far as the main jet if its even necessary
     
  15. PS almost forgot one of the other reasons i think its the pilot jet is because if i use the choke lever she runs a little better also meaning shes running to lean so if i use the choke it richens the mixture
     
  16. skyash

    skyash Active Member

    I got one of them carbys and no luck with eny of my bikes probably rong jet but I only got what come with it. It's in the carby bin with the Arthur one's. I tried every needle setting and turned the 2 screws in and out but no good. Looks nice
     
  17. You know what im truly baffled right now i set my c-clip to lowest setting did 1 and half turns out on air screw and like 2 turns out on the idle screw and for once she was idling it was a high idle of like 3800/3900 but still no top end can get it 25 MPH downhill only 21 on flat surface throttle cuts out at anywhere from half to full think i might need main jet i dont know yesterday was a bit colder today is a bit warmer so i will have to see how the warmer weather plays out
     
  18. SRPM

    SRPM Member

    Sounds like your running too rich. I re-drilled the jet down to .56-57 16mm #74 bit runs a lot better in the top end. I'm now hitting 30-31.7mph on flat surface and pulling strong up my test hill at 22-22.5 mph.
    What is your oil mixture, could be that you have to much oil in your mixture and could be fowling your plug. I recommend 32:1 for brake in then 40:1 if I need to. I also recommend changing your plug to an ngk b8hs spark plug part number is 5510, I put the one in that came with the engine and it ran like complete dog poo
     
  19. SRPM

    SRPM Member

    Also if you have the high compression head like I do I would put it on and see if that helps at all.
     
  20. skyash

    skyash Active Member

    I can get idle on all sittings but when I try to ride it goes then a bit to much throttle and cuts right out. To much to play with
     
Loading...