So your HT bicycle engine won't start, well let's take a look

Discussion in 'Motorized Bicycle Trouble Shooting' started by Al.Fisherman, Nov 9, 2011.

  1. Al.Fisherman

    Al.Fisherman New Member

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    Chinese HT engine won’t start? Well let's see what might be the cause of your problen.

    Electrical
    1. Improper wiring. Black magneto wire to black CDI wire, blue magneto wire to blue CDI wire. White…either remove or isolate.
    2. Kill switch defective. Do not hook it up until you get the engine running. When hooking up the wires, don’t pay attention to colors. One wire connects to the blue magneto/CDI wires; the other wire connects to the black magneto/CDI wires.
    3. Defective magneto..testing All readings are approximate.
    Use Low Ohm-Meter Scale 200 Ohms
    Check Ohms between BLACK wire and WHITE wire. 2 Ohms
    Check ohms between BLUE wire and WHITE wire. 300-400 ohms.
    4. Defective CDI..testing All readings are approximate.
    Use Ohm Meter High Scale About 200-K
    Positive lead on BLUE wire and Negative lead on BLACK wire
    infinite (no activity)
    Positive lead on BLACK wire and Negative lead on BLUE wire.
    130-150 K ohms
    Positive lead on Spark Plug wire and negative lead on BLUE wire.
    135-155K ohms
    Switch to Low Scale 20K
    Measure between Spark Plug wire and Black lead. 2.5 - 2.7 K ohms
    Magneto and CDI testing .. credit goes to 2Door
    5. Replace Spark plug (I like NGK’s plugs, number depending on your engines condition) also replace the high voltage lead from the CDI. Use a wire core lead.
    6. Check for proper timing. At TDC the cut outs in the magnet will be
    in the 12:00, and 6:00 position. The key will be at the 1:00 position
    7. Do away with the cheap connectors on the magneto.CDI. Replace with good ones, solder them and wrap with tape or better yet heat shrink as I do.
    8. Re solder the blue magneto wire. Have seen cold solder joints from the factory. I change the wire to a better grade and to a 16 gauge.

    Fuel
    1. Clean fuel tank, and screen filter (in the tank) out. Tanks have been known to have trash in them.
    2. Install an inline fuel filter. One might not be included in the kit.
    3. Carburetor piston, check for proper instillation.
    4. Carburetor to intake manifold leak. An “O” ring installed can help solve this problem. Check manifold gasket.
    5. Ensure that the internal components in the carburetor are installed correctly and not loose. Later you might need to adjust the needle (attached to the carburetor piston…5 different positions)
    6. Ensure the float operates correctly and the needle seals off the fuel flow through the seat.
    7. Tighten bowl screws.
    8. Screw on the NT carburetor only adjusts the idle.

    Compression
    1. Blown head gasket. Mill head replace gasket
    2. Broken rings. Replace rings/piston
    3. Leaking seals on the crankshaft. Replace
    4. Spark plug not tight or threads stripped.

    Vacuum Leaks
    Shouldn’t cause a no start problem, but can cause a RPM issues.

    If you don't have a Volt/ohms meter, I suggest you get one. Harbor gives them away quite often. I have gotten 4 of them. One in the house/garage/5th wheel and in my truck. ALL FREE
    [​IMG]

    Looking for any other causes that will lead to a NO START problem. Please don't make this a sticky till its finished...
     
    #1 Al.Fisherman, Nov 9, 2011
    Last edited: Nov 9, 2011
  2. 2door

    2door Moderator
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    Re: So your HT won't start, well let's take a look

    Allow me to elaborate on Al's check list, item #1.

    The plug in connectors that come in the kit, the ones on the blue and black wires from the engine and the CDI, are notorious for bad electrical connections. I had one, on the blue wire from the magneto, that was crimped onto the insulation and not the conductor. One of the best things you can do when installing the engine on your bike is to cut off and discard those little push-together bullet connectors then solder the wires together and protect the connections with heat shrink tubing.

    Item #1 under the fuel heading:
    Every kit supplied tank I've seen, and I've seen a few, needed to be cleaned of rust and dirt as it came from the factory. Installing one without at least rinsing it with fresh gasoline is almost a sure way to quickly clog the in-tank filter/petcock. A clean fuel delivery system is essential to a good running engine.

    Al, back to you.
    Tom
     
    #2 2door, Nov 9, 2011
    Last edited: Nov 9, 2011
  3. Al.Fisherman

    Al.Fisherman New Member

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    Re: So your HT won't start, well let's take a look

    Good call Tom on the connectors.. I automatically do that not even thinking about it.
     
  4. happycheapskate

    happycheapskate New Member

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  5. Andy101

    Andy101 New Member

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    Re: So your HT won't start, well let's take a look

    I am not getting a spark out of my plug, have been through this checklist and although the readings were a little high, still no spark. Its got a brand new plug and I tried a few different types. Everything seems to be setup right and its really starting to get to me. Is there any other reason its not sparking? It stopped working after about 2 mins of use the other morning and I have been over everything, I think.
     
  6. Al.Fisherman

    Al.Fisherman New Member

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    Re: So your HT won't start, well let's take a look

    Go through this list.... it's a update. You must of missed something simple.
    https://docs.google.com/document/d/1aBeJuoS--VQWwXysc07rpscTUbPzgc93xjiQBgsyFjc/edit?pli=1
     
  7. JCG

    JCG New Member

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    Re: So your HT won't start, well let's take a look

    I can't start the bike. Seems electrical. I did the tests listed above on Al. Fishermans 11/09/11 post. Items 1 - 3 OK Item 4. Ohms between black and white mag. wires=2.9 ohms. Ohms between blue and white mag wires = 332 ohms. Item 5.CDI test.Positive blue to negative black = no activity. Positive black to neg. blue=varies from 38.6k to
    41.9k ohms.Pos on spark wire to neg blue=varies from 41.9k to 50k ohms. Between spark plug wire and black=2.2k ohms. So.......I assume the CDI is bad? What would have caused that? When checking for spark, I took out the plug and grounded it on the head and cranked the engine. I saw a blue spark. Could this have damaged the CDI?
     
  8. Al.Fisherman

    Al.Fisherman New Member

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    Re: So your HT won't start, well let's take a look

    Checking for spark while grounding the spark plug, will NOT cause the CDI to go out. These electrical parts are built with no or limited quality control. I had 1 coil go out within 3 days for no reason at all.
     
    #8 Al.Fisherman, Jul 10, 2012
    Last edited: Jul 10, 2012
  9. JCG

    JCG New Member

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    Re: So your HT won't start, well let's take a look

    Is there an up-graded CDI I should buy, or just the stock ones for $10- $20.
     
  10. Al.Fisherman

    Al.Fisherman New Member

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    Re: So your HT won't start, well let's take a look

    Myself, I stick with the OEM. I personally have never had a OEM CDI go bad since I first build a bike (6) since 3/2009.
     
  11. JCG

    JCG New Member

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    Re: So your HT won't start, well let's take a look

    OEM ??? Is that a brand?
     
  12. killercanuck

    killercanuck New Member

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    Re: So your HT won't start, well let's take a look

    OEM = Original Equipment Manufacturer, the stocker.
     
  13. BikeBerryKelci

    BikeBerryKelci New Member

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    Re: So your HT won't start, well let's take a look

    Great advice!!!cvlt1
     
  14. dontellmymom

    dontellmymom New Member

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    Re: So your HT won't start, well let's take a look

    Hey JCG,

    Did you ever get the bike running? Was it the CDI? haanh?

    Thanks for the info.

    Be Safe.
     
  15. Tyler6357

    Tyler6357 Member

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    Re: So your HT won't start, well let's take a look

    great tips!
     
  16. blunted429

    blunted429 New Member

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    Re: So your HT won't start, well let's take a look

    i am about to post pics of the silicone job i did for the wires.
     
  17. AzRigidRider

    AzRigidRider New Member

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    Re: So your HT won't start, well let's take a look

    Hey everyone I'm Alex, I know this isn't the introduction page but I've peeked around a little and finally registered. The info and atmosphere here is on point! I've been scootin around on my 66cc motorized bicycle for a couple months now without any MAJOR problems however about a week or so ago I was on my way home from work and my motor seized, obviously compromising piston and cylinder but without and further damage... I believe. Crank still rotates smooth as can be so I ordered a jakes jug and cut on piston from jakebike.com and installed accordingly but WILL NOT start whatsoever! That being said I have looked everything over top to bottom and it all seems to be in order. I am stuuuumped! If anyone has an idea I'd greatly appreciate any input! :-||
     
  18. Tyler6357

    Tyler6357 Member

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    Re: So your HT won't start, well let's take a look

    I would replace the head gasket if you installed a new piston and jug. You might want to check gasket at the cylinder/bottom end seal as well. Also, make certain that you are getting a spark and that the carb is clean and flowing gas.
     
  19. crassius

    crassius Active Member

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    Re: So your HT won't start, well let's take a look

    these days there are diff pistons & barrels out there to fit the diff rod lengths - first step would be to compare your old one to the new one to see that all measurements are the same
     
  20. AzRigidRider

    AzRigidRider New Member

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    Re: So your HT won't start, well let's take a look

    Hmm good call Tyler, I haven't replaced head gasket but did get a bottom gasket along with jug and piston with upper needle bearing and wrist pin. As far as spark haven't been about to confirm sparking I will have to take an ohm reader to magnito and ignition. I've got a NGK bp7hs that isn't even a month old with minimal carbon build up but guess there's a chance of it being foul if ohms check out. And for carb, is there any specific methods for checking good flow?
     

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