CARBS...I give up

Discussion in 'Motorized Bicycle General Discussion' started by Kevron99, Nov 3, 2009.

  1. Egor

    Egor New Member

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    How does the carb work when you are under power? Do you seem to have normal throttle movement in the twist on the bars? In the pics it looks like everything is OK. I did have an engine that had a bad case gasket and it would not idle and was fussy, but would go OK. If the throttle cable is too short it will hold the throttle open also, check at the twist handle and make sure the boss is threaded in all the way. I have done a lot of mods to this little carb and it works OK with the mods, but you have a unique problem. Have fun, Dave

    PS: Keep it up you will find the problem, and it is not electrical.
    http://motorbicycling.com/f13/stock-carb-mod-1494.html
     
  2. neicull

    neicull New Member

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    That's a pretty unique problem .. Post a video with the handle bars and you operating it in view. Then trace the throttle cable and clutch cable with the camera close up for us. I'm curious as to how or why the engine would rev and then stall when you pull the clutch in... Can you rev the motor with by twisting the throttle?
     
  3. rockvoice

    rockvoice New Member

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    Looks like the carb is not all the way pushed on the intake (airleak) and why is the fuel filter sideway's with the fuel going uphill to the carb. might need to shorten the fuel line so its all downhill to the carb.
     
  4. george_n_texas

    george_n_texas New Member

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    I know the fuel filter looks full of fuel but it is going uphill towards the carb and it is a paper element in colder weather and thicker oil for breakin I had the same problem. Once the fuel is spent from the bowl and it ain't sloshin around rollin down the road you have fuel starving...just for grins bypass the fuel filter and see if it helps. The stock tank has a screen filter in it. Second thing I notice is you put both springs on the actuator side of the clutch cable I did the same...the big spring is for a heat shield on the cable on the other side of the standoff. I took both springs off jrom the actuator side there's plenty of return from the clutch internal springs. Pictures almost always help. I also noticed you air filter seems to be squeezed against the seat post I'd elbow the carb to the side as that seems to me would be jarrin the carb alot.
     
  5. Kevron99

    Kevron99 New Member

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    Posting a video will be my next step this weekend. I am still figuring out how to take video with one hand and the other on the clutch lever. Not only that...I still have to run the bike first then come to a full stop with video cams on my right arm is quite susceptible to crash...but I will take videos this weekend.

    As of right now all I can do is take pictures...
     
  6. bairdco

    bairdco a guy who makes cool bikes

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    your intake looks like a piece of junk.

    didja try spraying it with carb cleaner to see if it has any leaks?

    i'd get rid of those acorn nuts and replace them with regular nuts. the acorns might be stopping the intake from tightening down all the way.

    and like it was mentioned before, take the springs off the cable. the bigger one goes on the cable housing to act as a heat shield for the housing, and the smaller one isn't needed as a return spring. it'll save some wear and tear on your wrist.

    where the cable goes into the carb at the top, it looks like it's sticking up kinda high. mine has about an 1/8 or less of the silver cable end sticking out.

    make sure yours is seated in there, and moves around smooth. once, on mine, the cable pulled up and stuck for a minute, causing hi-revs.

    keep trying, we'll figure it out.
     
  7. Technocyclist

    Technocyclist Motorized Bicycle Senior Technologist

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    i suspect it's an airleak somewhere, probably the oil seals... better check it out... when there's no idle, i check for airleaks first before messing with the carb...
     
  8. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I posted something last night, but I guess the computer ate it...As far as the thing dying when you pull the clutch ALL the way in. Maybe the set screw is rubbing against the clutch cover and killing the engine? Pop off the cover and have a look.

    The other problem is an air leak from the sound of it, and I would look at that funky lump or weld or whatever is on your intake. It only takes a pin hole to muck up the works.
     
  9. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Excellent advice there, bairdco.
     
  10. Kevron99

    Kevron99 New Member

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    Sorry I am new to this terms...what is the boss? As far as the throttle goes..It springs back really good and is not short.
    Thanks
     
  11. Kevron99

    Kevron99 New Member

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    Thanks to all the members of the forum for standing by me resolving this issue. I will post a video really soon.
     
  12. Maxvision

    Maxvision New Member

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    You might also be drawing air where the carb clamps on to the intake pipe.
     
  13. pnz

    pnz New Member

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    Did you get it to Idel
     
  14. Nashville Kat

    Nashville Kat Active Member

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    I'm just going to throw this in here- having skimmed some of the early posts, but not having read this whole thread-

    Does the fact that your fuel line is not working with gravity have an effect?- from the pictures earlier it looks as if the fuel filter is BELOW the carb- The motor uses very small amounts of fuel- does it suck that hard through all revs? have you run it with a more verticle line, or with no filter?

    just some thoughts...
     
  15. Kevron99

    Kevron99 New Member

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    Nope..it still not idling. The engine still revs high on clutch lever half way press and engine stalls at full clutch lever being pressed.

    Here's what I have done and still not idling.
    1. Made sure clutch cable is not binding with throttle cable
    2. Remove clutch spring cable.
    3. Re-overhaul the carbs and clean with carbs cleaner. Made sure I can see a tunnel running through the jets and no clog.
    4. Re-orient the gas line to upright vertical position.
    5. Change the spark plugs to NGK B6HS and gap to 0.28
    6. Replace spark plug cable to 7mm Accel copper braided high voltage radio resistant cable (really cool)
    7. Solder and insulate (heat seal) the cdi black and green wire to the magneto wire. Now it is permanently attached.
    8. Bought new fuel and mix 20:1 synthetic oil
    9. Punch small hole on gas cap
    10. Make sure the throttle springs back and the slider needle is set to proper position
    11. Tried different needle e clip position from first slot to the fifth slot.
    12. Inspect clutch, magneto and engine sprocket for anomaly (everything looks ok)
    13. Made sure throttle cable has no slack and not to tight.

    After all this...I will replace:
    1. Carburator
    2. Throttle cable (the cable that is currently installed has a very small bent or kink inside the throttle housing)
    3. New SBP gas filter
    4. Intake Manifold - Dax
    5. Throttle housing with kill switch - Dax

    I am awaiting all of the above parts to arrive. I hope one of this parts will solve the issue.

    Thanks - I will let you know of the progress.

    Kevron / Ron :-||
     
  16. george_n_texas

    george_n_texas New Member

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    I hate to say this but you would be surprised how many computers I have fixed by a simple wire being unplugged...have you tried bypassing the filter that is running uphill to the carb?
     
  17. wjliebhauser

    wjliebhauser New Member

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    This is a stumper. Kevron99, and with deference and respect to all the other posts, I wouldn't spend too much time messing with anymore electrical at this point. I cannot imagine any scenario where the mag, plug, or wires could keep the thing from ideling down. Kill it, yes, as was suggested, if the stress-movement of the clutch lever, cable, or actuator is causing a bare wire to move and short or disconnect...but not prevent idling.

    I think you have two unrelated issues. Here are some ideas:
    - motor kill on full clutch disengage: pull the clutch cover (plate with screws on right side, opposite of chain sprocket). look at the inside of the cover to see if there are any marks on the inside of it. Work the hand lever and see if it all seems to be working correctly. Go ahead and start it and see if it still dies with the cover off. I think maybe something is wrong, maybe in manufacture, causing the clutch plate or shaft to be pushed out past its design limit, and the clutch plate or shaft is jamming against the cover, or the shaft is too long...or the actuator cam on the other (left side, behind another cover) is in wrong, sloppy...or it is adjusted too far. I don't think you should have a fully disengaged clutch at only 50% of lever pull, it should be adjusted so it is just barely disengaged when the clutch lever is held down by the little 'locking' button...somethng ain't right.

    -idle: I would reroute the fuel line to make a straight gravity flow to the carb too, but that is to prevent air locks or other issues. I trust you know if you have sealed and tightened the carb and intake. And a small air leak will keep it from ideling low and nice, but not keep it racing all the time. Fuel line looks like it is siphoning ok, and I can't see how it would keep it from idling if it is getting enough fuel to run at igh speed. My guess: On my initial build, I had the throttle cable too tight; you have to be careful up at the throttle handle end and at the carb. It looked fine all buttoned up on the outside, but the throtle was at least 50% open when the hand throttle was fully released. Take that throttle mechanism all apart, and reassemble it carefully to make sure the cable in the hand throttle is threaded right and throttle is rotating through its full arc with the cable on, same as it rotates without cable.

    Hang in there! Take it from an old man, stuff like this can drive you crazy, but I can honestly say, after 40+ years of wrenching, when you finally figure it out, you will a) kick yourself for not seeing it sooner, and b) have a grin from ear to ear! I can tell you are frustrated, but you'll get it. It's just some metal and plastic parts and pieces, and you can outsmart it!
     
  18. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Did you ever pull the clutch cover to see if that's what's killing it when you fully disengage the clutch?
     
  19. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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