Discussion in '2-Stroke Engines' started by FrenchFRI3S, Feb 12, 2015.

  1. FrenchFRI3S

    FrenchFRI3S New Member

    Hey guys, been riding for a couple of months now. I bought my kit originally on ebay paid $125 for it. My motor still has good compression but i'm fixing to replace the cdi. I can however run my bike but it won't idle and it wont full rev either(atleast not close to what it can do). i started off with a 36t on 20" wheels. I could hit 32-34mph but thats pushing it. I generally ride around the 25-28mph range but with the small wheels it would take off rather fast and to me it seems like it was getting into higher rpm ranges to early. Now 3 days after installing the new kit the electrical went out. I replaced both the mag and the cdi and it ran great for about 2-3months and now it hardly runs. I just replaced the mag with no change in running condition. Could it be my cdi or possibly the carb? Is it possible i may have gotten something in my tank? It doesn't run any better or worse when i remove the tank lid so i know it's not vapor locking. i just want to be sure before i order anymore parts. I have the stock nttc carburetor, exhaust head. Stock kit basically. Could really use some incite though. Any and all suggestions will be appreciated.

  2. jaguar

    jaguar Well-Known Member

    test the stator coil while pushing the bike to see if it outputs at least 30 volts AC. disconnect it from the cdi first.
    sandpaper the shellac off the stator coil frame where the screw heads rest. that is an important ground path for the ignition.
    plane your head with sandpaper on glass since the head is warped from the start.
    take off the air filter and blow thru it to see if there is any flow restriction and toss it or clean it if there is.
  3. FrenchFRI3S

    FrenchFRI3S New Member

    I do believe I have some sand paper around from one of my other projects. That isn't a bad thought tho, I suppose i can see about getting a volt meter as i do not own one. Would a cheap possibly "knock-off" volt meter be persistent enough to help regulate this project or should i go borrow a good one from a buddy. Also i ordered another cdi as well just to be sure my problem isn't electrical. If i'm not mistaken these stock cdi units aren't very well stable with higher rpm as i mentioned before. I'm currently on a Rand mountain bike frame w/ballistic thread-less front end (steel) <-- done with aluminum frame due to it being warped in a left curve. It served it's life as a daily road bike from my brother and it had alot of miles before even having a motor installed to it so that really didn't help. lol :p I have left to tighten a few things down and the bike should be completely suitable for use. I used to ride bmx bikes daily so i can keep one maintained for years. I'll go over my spoke's, bearings, front end, etc.. before use. I want a healthy feeling bike if you catch my drift. Also, Have you ever tried adapting regular caliper brakes to v-brakes? They make a plate that mounts to the caliper mounting hole but, i'm not quite sure one bolt holding v-brakes down is considerably "safe" for this type of project. We always used v-brakes on the track due to their effortless ease when it comes time to apply them. Would you suggest any particular brake pads as i can see these going pretty quick. You think i should need to resurface the head? seems like much but if it's necessary for these it's no big deal. Thanks in advanced!
  4. jaguar

    jaguar Well-Known Member

    get a cheap analog meter, not digital. look in Radio Shack.
    All these MBs need front disk brakes for safety reasons.
    FrenchFRI3S likes this.
  5. FrenchFRI3S

    FrenchFRI3S New Member

    I'd like to understand the safety reasons for only recommending that type of brake set considering i'm not spending more money just for a new front hub, then lacing it and still having to buy the brakes and the adapters to mount the disk calipers down. I've rode one around for 2 months without any brakes being capable of stopping myself with nothing but my feet whilst ruining heavy boots. Does that even count? lol
  6. KCvale

    KCvale Motorized Bicycle Vendor

    I can't read your gigantic run-on paragraph posts bud, you know it's OK to hit enter every few lines so break the text up right?

    Anyway, this is my technique to solve possible ignition problems.
    You need a good multi meter for this otherwise you are just ****ing in the wind replacing parts that may be just fine.

    Disconnect everything.

    Ohm the black magneto wire to a head bolt, it should read a dead short.
    If not, check the ground tab on the magneto.
    The new skyhawk CDI's have no white wire, ground is the lower connector but it has a wire from it to ground.

    Old style mags with a white wire have a tab out of the mag that solders directly to the mag base and they can come loose, just hold it down and re-solder.

    Ohm the magneto from the black and blue wire, 320-380 ohms is ideal, an open or dead short means a bad magneto if the wires are connected.

    Ohm the CDI in the 10K-20K scale.
    Red+ meter probe to CDI black wire.
    Black- meter probe to the spark plug cap.
    You should get about 6.9K ohms give or take a K or so.

    If not it could be a bad wire or cap.
    Unscrew the plug wire at the cdi, use pliers or even cut it off and dig the junk out if need be and do the same test above again to the cable screw on the CDI.
    If that works get a new wire and plug cap, if not you have a bad CDI.

    If all of that is good there is only one thing left, the magnet.

    That was indeed the problem with this repair on a new build with a 2014 gasbike.net front page engine kit.

    When you pull the 4 bolts out of the magneto mount it should slam itself against the magnet, I mean to the point where it is hard to even get your first bolt in.
    A weak magnet that lets you move the mag around pretty easily is not strong enough to create a spark which is what this repair had.

    Magnet replaced, problem solved and my repair is done.
    FrenchFRI3S likes this.
  7. FrenchFRI3S

    FrenchFRI3S New Member

    Well, as it turns out i burnt a plug. Replaced it with an NGK plug and has had no issues since. Also (off-topic) would this be a possibly usable work around to reattach the bicycles drink holder with something of this sort? Maybe you know a better idea, I'm just not a basket kind of guy. Also I have 2x 12v 12ah batteries from a broken scooter and the signals and lights are being installed to the bike. The batteries run the lights and the horn fine for now but, I will invest in a 12v to 24v step-up converter to wire the scooter accessories to one battery to reduce the bike's weight being i've taken the electric motor out of the equation. For now it makes practically forever lasting light and a heavier feeling bike. I also have a trailer that I plan to make a quick connect from the bicycle to that so I can have running lights on that aswell. Tell me what you think guys. Also, thank you in advanced!
    Last edited: Mar 4, 2015