HT quit while riding ???

Discussion in '2-Stroke Engines' started by jmccrury, Aug 6, 2008.

  1. jmccrury

    jmccrury Member

    I have a 49cc HT that I put together about a week and a half ago. I've only put a little over 30mi on it. The only problem I've had so far is that I stripped the threads out in the exhaust mount, but that's fixed. Anyways, I was driving home yesterday and everything seemed to be going good when suddenly the motor just lost power and died.

    I've made sure that it's getting fuel, checked that the carb is functioning correctly, and disconnected the kill switch. It just sputters a little while I pedal, but that's it. I haven't got to check the spark plug yet so I'm going to do that when I get home this afternoon and I will post an update. Has anyone had this happen before?:confused:

  2. lildeezul

    lildeezul Member

    I having the same problem. my motor just died... My kill switch is stock, but its connected to the blue and black wire, comming from the coil.

    Also i check the spark plug it looks fine, but idk if it fouled becuase i just change it like 3 weeks ago.

    but i will also change the sparkplug/wire.. and disconnect the kill switch and see what happens
  3. lildeezul

    lildeezul Member

    well took off the kill switch, still doesnst start.

    how do i check if its getting spark or not
  4. jmccrury

    jmccrury Member

    You should be able to turn the motor over without the spark plug screwed in to see if it fires.

    I did have a minute on my lunch break to take mine out and look at it. It's oily and gritty. I'm going to look around on here to see what it should look like. This afternoon I will have someone to help me check to see if it's working or not.
  5. lildeezul

    lildeezul Member

    ok.. i check that..

    my sparkplug wasnt oil nor gritty. it looked perfectly fine..

    but anyways, hopefully my magneto or CDI inst bad.. how do i check the resistance of the magneto, what wires should i test, and wat should be the readings..

    sorry for the hijacking
  6. crazeehorse

    crazeehorse Member

    have you tried taking your plug out, hook the wire back to the plug, hold the body of the spark plug against the head.with the clutch lever engaged, hold the rear wheel off the ground, & either turn the pedal cranks, or the back wheel to make sure it spins. check the mag on the highest scale on resistance, if you get a reading it's probably ok.(you should be able to check the blue & black leads form the motor.) the cdi uses capacitance, but i don't know if you can check it like a capacitor.
    Last edited: Aug 6, 2008
  7. lildeezul

    lildeezul Member

    Got it working.... What i did is that, i took the sparkplug out, and i put the boot on the sparklug, and place the sparkplug near the fins of the head. I locked the clutch in place, held up the back tire, and kicked my pedals like a kick starter... and Waaaaa laaaaaa... there was spark...

    Right then and there i knew it was a fuel problem... Took off the float, and there was gas, so i look at the main jet ( nipple that covered the bottom half of the needle) and it was clogged with some blue RTV gasket stuff that i used to stop the carb from leaking earlier..

    The Blue RTV gasket stuff was like goooie.. i think the gas melted it.

    anyways is there like a gasket stuff that is resistant from gas, and y telfon tape eroded too. its there a replacement that will seal the threads, and gaskets that is resistant to gas
  8. jmccrury

    jmccrury Member

    Glad to hear that you found the problem. There is gasket sealant that is resistant to gas/oil. I saw it in tractor supply a few days ago and it was only a few dollars for a small tube. I'm sure auto parts stores probably have it too.
  9. crazeehorse

    crazeehorse Member

    i got some fiberized rubber gasket material at napa auto parts. i also used made 2 gaskets , & put them together to replace my gas cap gasket which leaked, & that worked too. i paid 9.00 for a roll, but it will last a long time.
  10. jmccrury

    jmccrury Member

    I checked to see if it was firing last night and there was nothing. Not even with a new spark plug. Well, I say nothing, but there was a little something when I decided to ride it down the road really fast and try to start it. I could hear it fire a couple of times but that was it. I'm guessing the magneto is bad. Any other suggestions?:???:
  11. crazeehorse

    crazeehorse Member

    if you have a spark at all , your mag is probably ok. your cdi is what boosts the spark.just take your time look over all your wiring, very carefully. you may be grounding out somewhere. do you have a multi meter? if so i'll see if there is a way to check the cdi with a meter. is your motor still in warranty?
  12. lildeezul

    lildeezul Member

    Curry, Do what i did.

    Test your spark out... you have to look pretty close...

    Take the plug out, but keep the boot on, and place the electrode near the fins of the head, and lift up the rear tire, and kick the pedals, and dump the clutch...

    also since u said u felt it spark going down the hill... do this.

    Take out your spark plug, and pour some gas in the sparkplug hole ( that way gas is in the cylinder. put the plug back in, and try to start it.. if it starts, then something clogging the gas, and would look at the carb
  13. crazeehorse

    crazeehorse Member

    ok here it is,
    cdi- resistance scale k-ohms blue lead to black lead 303 k-ohms, same reading from blue lead to plug wire 303 k-ohms, & last , black lead to plug wire 2.5 ohms (just ohm, not k-ohm)

    mag- resistance scale ohms, reading blue to white ,350 ohms, same reading for blue to black, 350 ohms, & last, black to white should read 2.5 ohms

    like with most readings of this type , if its within + or - 10 % it's ok.
    if you have a bad part, it will most likely read infinity, or open circuit
  14. zetti_the_man

    zetti_the_man Member

    proly jus flooded. but idk.. dont go full throttle. you most likely dont need to. but idk man..
  15. jmccrury

    jmccrury Member

    I still can't find the problem with this thing. Here's what I've done so far.

    - Disconnected the kill switch
    - Made sure fuel valve is not clogged
    - Replaced spark plug
    - Took carb apart to make sure it was not clogged
    - Replaced magneto

    I don't really know where to go from here. When I checked for spark with the old magneto I didn't see anything. How hard is it to see the spark if it is working? I didn't have time to check it this morning with the new magneto, I just tried to start it which failed. I will check that when I get home this afternoon. If that doesn't work then I'm guessing it's the cdi, but who knows. This is getting really annoying.:mad:
  16. crazeehorse

    crazeehorse Member

    unless your're in direct sunlight you should be able to see a spark,it should be a bright white, or blue spark. did you take your plug out to see if it has gas on it? it sure sounds like the cdi, but get someone to check it with a meter first.
  17. jmccrury

    jmccrury Member

    Here's a few more things I tried tonight.

    - Removed exhaust to make sure it was not clogged
    - Adjusted clutch cable to make sure it was engaging correctly
    - Removed spark plug and there was fuel on it
    - Put starter fluid directly in cylinder and it still did nothing
    - Checked for spark again with the spark plug out and I couldn't see anything. I was going to check it by touching the plug but I didn't have enough hands and no help tonight.

    I think it is the CDI, but I'm going to borrow a multi-meter and check before I spend any more money. :(
  18. jmccrury

    jmccrury Member

    I was wondering if there is a different cdi that can be used with the HT motors? Maybe something that can be bought locally at a tractor supply or small engine shop. I was just thinking that I could try it to see if it worked and if not it could just be returned.
  19. crazeehorse

    crazeehorse Member

    i,m not sure about that, some small engines (lawn mower, & such) have the same type system. i do know once you hook up electrical parts they usally can't be returned.if you want to haul it over to leach, i'll check it for you, or you can one of try mine on it, i have 2 bikes.
  20. Bronzebird

    Bronzebird Member

    Manual states to keep the CDI dry.

    Has the unit been washed or riden in rain. Silcon to seal the wire outlet seems prudent.
    I check spark in a gardge with it rather dark or at night. Yellow spark is weak and will not be enough to supply combustion. Like someone earlier stated hot white or blue spark is good.
    I got the 80cc and I'm sealing my CDI, NOW.
    Sorry to hear about the problems. Kinked or poor conections can cause resistance or a broken wire. You have to "feel" the wire or test end to end with meter.