Carby My C Clip does not agree with me

Discussion in '2-Stroke Engines' started by Waxxumus, Jun 8, 2015.

  1. Waxxumus

    Waxxumus Member

    Well, when receiving the bike the C Clip was in the position of 2nd most lean (2nd from the top) and when warming up and riding, I often get white smoke, plumes of it. Once warmed up and the choke opened I get much less white smoke, but the engine endlessly 4 strokes.
    Bear in mind here that I am on my 3rd tank after running a gallon of 16:1 through it at this richness. Lots and lots of white smoke.
    It is apparent that the spark plug has been fouled and is covered in black.

    I attempted to see if any performance gain could be made or if the engine would run better if I placed the C-Clip at the highest notch (Leanest)
    The engine Idles much much better, ended up having to turn the idle screw down because of this.
    And it warms up quickly. Almost too quickly. It has me worried.
    When riding in the 2nd notch from the top, even under heavy load, i can normally touch my engine without getting 3rd degree burns.
    When riding with choke all the way open and leanest mix @ 6oz oil per gallon. roughly 1:20/22, the engine gets quite hot, hot enough to burn you if you touch it momentarily.
    But there is no white smoke.

    I suppose a plug chop or 2 is in order. But the plug is already fowled.... not sure if this will affect results.
    In your experience what is a good operating temperature for these motors? F or C i dont care.

    I have a laser measure for heat, and can take the temp of the engine quite quickly and accurately.

    Or is there a way to judge the heat by hand? Or should the engine be hot enough to give you char marks across your leg if you graze it? XD
    It sure picks up a hell of alot faster. and i can actually get it to 2 stroke for awhile.:detective::detective:

    Also, would you advise me running the engine richer for awhile longer?
    I am only on my 3rd tank of gas.

    Its a Stinger SD kit, with NT carb. I could imagine the limited air flow of the stock air filter causing some enriching of the mixture or causing 4 stroking, but it 4 strokes with the choke about half way up, and rides exactly the same at half choke as if the bike were on the 2nd notch at fully opened choke. The idle also shot up dramatically after reseating the carb, pretty sure there was a small air leak, plus the securing screw was vibrated loose to the point you could move the carb around. (I dont believe my carb came with a gasket to properly seal it, have used rubber o ring to great effect.)

    Since Im still slightly in the break in period, and have been reluctant to go full throttle too often, would you reccomend running oily until i have leaned out the gas to see if its just the rich mixture causing my 4 stroking and loss of power and plumes of white smoke? Or should i ride it with the choke half on, and warm it up at 10% open?

  2. crassius

    crassius Well-Known Member

    I'd go to 32:1 (4oz/gal) and run it like it is, but be sure to check plug every tank or so to be sure it doesn't get a lot leaner as the rings seat better.
  3. KCvale

    KCvale Motorized Bicycle Vendor

    Spark plugs have a Heat Rating in the middle of their number.
    They vary by maker, for NGK plugs the higher the number in the middle the more heat it dissipates out of the engine.

    Look at the size difference in the white insulator length where the plug threads are.


    The more white you have in contact where the threads are, the more heat is transferred to the cooling fins, and the pink is just providing an air gap to keep heat in.

    * If the engine is to be operated at high RPM, under a heavy load, or at high temperatures for long periods a colder heat range may be needed.
    * Conversely, if the engine is to be operated at low speeds or at low temperatures for long periods, a hotter heat range might be needed to prevent fouling.

    What you want is a plug cold enough to dissipate all you can, but not foul the plug.
    Your engine is not getting hot enough for the plug to self-clean from the heat so drop the middle number to make it hotter.

    I didn't catch where you live but this is the **** plug if you live in the heat like I do, this is the plug I use to replace all 2-stoke engine stock spark plugs.
    NGK 5944 (BPR7HIX) Iridium.

    You may need the colder 6 if you are fouling out...

    Heck, get both and see, regardless you will see an instant improvement in efficiency and they are idiot proof, they come pre-gapped and not to be re-gapped!
    Waxxumus likes this.
  4. Waxxumus

    Waxxumus Member

    I have a BPR7HIX in the mail :D
    All is good
    Will get a 6 ordered from local parts store later.
  5. Waxxumus

    Waxxumus Member

    What do you mean crassius?
    Toward the lean notch, or where it originally was one down from the top?
  6. Waxxumus

    Waxxumus Member

    For instance, I have to start it @ 40% choke with the 2nd notch down to keep it idling before it bogs down and quits. (It has been running like this since the beginning)
    At the Top notch, it idles no problemo @ 15% choke open, never loses power or dies when going from complete stop (Which happens on the 2nd notch down), but the heat of the motor is just concerning.
    Its as if I just started it the first time and the seals were fresh and full of friction, and the motor is hot enough to cook meat on.
    On the 2nd notch, the engine eventually worked itself to the point where at 100% open choke the engine can be touched for a few seconds without burning yourself. Is this too cold?
  7. Waxxumus

    Waxxumus Member

    Well, after giving the plug a good scrape with a bristle brush, and removing the gunk, I did a Plug Chop.

    At mid to high rpms, its just where it needs to be. That milky brown color. Not black, not white and burnt.

    Hopefully this NGK sparkplug makes more improvement. It already pulls drastically harder off the line.

    My 4 stroking could be due to the fact that my spark plug is gapped at .038

    Think i should shorten that?
    Last edited: Jun 9, 2015
  8. Slogger

    Slogger Member

    I guess I'll jump in here, yeah, you should start somewhere between .024 and .028 they say.
  9. KCvale

    KCvale Motorized Bicycle Vendor

    You don't gap that Iridium you bought, it even comes with a protective cardboard sleeve over the threads to insure it doesn't get altered in shipment.

    It takes a larger plug wrench than stock so get yourself a 13/16th long socket.
  10. Waxxumus

    Waxxumus Member


    I have heard this many times.
    Im assuming because of the ease of breaking the little arm.
    But rest assured I shouldn't be touching the gap on the iridium, Im using stock at the moment, and Ill try bringing the gap down in the mean time.
    Luckily enough, I have a box of assorted tools to pull from and a couple sets of metric and non sockets.
    Life is easier with the right tools :D
  11. Waxxumus

    Waxxumus Member

    Ive heard anywhere between .024 and .036

    Is there any reputable source which has the gap specs for the chinabike motor?
  12. Slogger

    Slogger Member

    I've got mine at .030 because I can get away with it. I have an HD lightning with the separate coil, I guess it makes more spark juice.
    The .024 to .028 is just the opinion of lots of motorbike guys. I read a lot.
    Nothing chiseled in stone. People get good results gapping them that way.
    They say the spark is more reliable at low RPM, like when your trying to start the engine. It makes sense, less gap is easier to jump.
  13. butre

    butre Well-Known Member

    I gap at .035 generally, but different motors want different gaps
  14. Waxxumus

    Waxxumus Member

    Seeee what I mean.
    I have had no problem whatsoever in starting with a .038 gap.
    I just got 4 Iridium tipped sparkplugs for the price of 1.
    I think there was a mixup @ the factory.
    Hot dang I just saved 24 bucks.
  15. Waxxumus

    Waxxumus Member

    So I have recieved some iridium tipped NGK sparkplugs.
    And I notice.
    They are about a half a millimeter - one millimeter or so longer.
    Is this cause for concern at all?
  16. Waxxumus

    Waxxumus Member

    They are the exact you specified.
  17. crassius

    crassius Well-Known Member

    gap may differ depending on whether you have 250ohm, 350ohm, or 480ohm mag coil
  18. KCvale

    KCvale Motorized Bicycle Vendor

    Only if you have messed with your head, like milling it.
    That little extra length gives you a little extra compression to go with the much larger spark you will be getting ;-}

    Don't short yourself with a crummy connection between the Mag and CDI, those 'quick connect' couplers are junk.
    I don't even **** with stock wiring, I run black very flexible double insulated 16g speaker wire from the mag to cut down leads on the CDI and solder.

    Note this wire is red and white not black and blue.
    I use red for blue (hot), white is the black ground

    For old style mags with the useless white wire I just cut that off.
    If the Mag ground is good you can ground your CDI ground wire anywhere.


    For the new Mags the bottom lug is ground.
    No soldered tab, which means it's need a wire to ground.
    I solder my white ground wire to the lug, but you have to make sure you don't remove the mags ground wire.
    This the ground your spark plug needs to work.


    Run your new wire however it looks best up to the CDI and solder up it and kill button to the CDI.


    Cap it off with a little hobby box or something and you have a pretty bulletproof ignition system, you can even put a keylock switch in there..

    What gets many people is wire colors.
    The ONLY important things is the Top lug of a Mag goes to the Blue wire on the CDI, and some ground to the Black CDI wire.

    You actually don't even need 2 wires from the Mag.
    A single fat hot wire from the blue mag to the blue CDI wire and then just run the CDI's black wire to a frame ground and it will work, the rub is using the frame as you ignition ground, paint and such tends to add resistance to the circuit so I run a pair of wire just to be sure.

    Just tips, not 'must do's' or anything, just that little extra attention to details that not only make it look better, but make it a better more reliable machine.
  19. butre

    butre Well-Known Member

    I just changed my gap from .035 to .025 and can confirm easier starts but I developed significant 4 stroking at high rpm. I'm not sure whether I actually lost top speed or if my intentionally rich jetting is just coming out more. I'll test it out shortly.

    actually, I just cracked my intake manifold, I'll be out of commission for the rest of the day now. it's a hairline crack so it still runs and doesn't seem to leak but hairline cracks turn into broken in half rather quickly. I changing the jetting won't do me any good today.
    Last edited: Jun 11, 2015
  20. Slogger

    Slogger Member

    Edit: I didn't see your edit when I wrote this.

    I don't know if it's a spark issue, but maybe try .028/.030. Your slightly smaller spark may be letting you down on top.
    Trial and error, that's my method.

    My engine has always been a little too rich, only here lately I finally got it leaned out. No more baked valvoline on the piston crown and plug.
    If I told you my main jet size, I'd spend an hour typing because it would set off a dogfight over jetting, it's that odd. My air filter is a genyoowine Dellorto SHA part, steel mesh that is very restrictive. The vacuum is so high behind it I had to go small on the jet. Very small.
    Each one really is unique, with all these carb/manifold/pipe/head and porting choices out there trial and error is about all we have.
    Last edited: Jun 11, 2015