No spark!!
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Thread: No spark!!

  1. #1
    Registered User Array
    Join Date
    Apr 2006
    Location
    Peachland, BC
    Bike
    1981 Honda CM400

    No spark!!

    Having trouble getting my old MX175 to run.

    Had a bit of spark, though pretty weak. Poured a bit of gas in the chamber and it fired and ran for about a minute until it died.

    Checked again, no spark. Let it cool down for an hour or two, still no spark.

    Checked the stator resistances against the shop manual, everything is in spec. Only thing is, the source coil (larger coil with a lot of copper wires wrapped around) has a small sort of cut across 3 of the coils.

    The ignition coil primary resistance is within spec, the secondary resistance is twice what it should be. But, got a replacement coil and it's the exact same reading....

    I dont' know, does anyone have any ideas??

    Thanks

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  3. #2
    Registered User Array emaxx's Avatar
    Join Date
    Feb 2005
    Location
    Aldergrove
    Bike
    Prev. FJ600/Current Raptor 660
    Quote Originally Posted by burnt03
    Having trouble getting my old MX175 to run.

    Had a bit of spark, though pretty weak. Poured a bit of gas in the chamber and it fired and ran for about a minute until it died.

    Checked again, no spark. Let it cool down for an hour or two, still no spark.

    Checked the stator resistances against the shop manual, everything is in spec. Only thing is, the source coil (larger coil with a lot of copper wires wrapped around) has a small sort of cut across 3 of the coils.

    The ignition coil primary resistance is within spec, the secondary resistance is twice what it should be. But, got a replacement coil and it's the exact same reading....

    I dont' know, does anyone have any ideas??

    Thanks
    Did you measure the resistance on the plug wire itself? Also, I'm thinking that if it ran for a minute its not anything to do with the coils. Might sound simple but did you try another spark plug as well? Yours could have got fowled up with your run in and got some carbon between the electrode peices and shorted it out...had that happen before. Those stupid things cause more greif than anything, and although quality is better than it used to be its not perfect...I've had brand new ones that were no good. (Known by not getting my bike to fire with one of the plugs in the package and then trying the other plug in the same package and it fired right up...put the first new plug in and no go!)

  4. #3
    Registered User Array
    Join Date
    Apr 2006
    Location
    Peachland, BC
    Bike
    1981 Honda CM400
    The resistance across the actual plug wire was minimal.

    Put in the other ign. coil and re-gapped it smaller (was on the wide side of the range, .0030 or so) and it fired.

    I don't know what the heck it did, but it seems to run now. Have to see how long it lasts.

    I believe I have some new plugs at home (bike is at in-laws) that I can bring up next time to have on hand if more problems start cropping up.

    Thanks for the advice!

    Shawn

  5. #4
    Registered User Array
    Join Date
    Apr 2006
    Location
    Peachland, BC
    Bike
    1981 Honda CM400
    Alright, new problems!!

    Was running fine, tried starting it tonight and not running so well.

    Seems to fire and run for a few kicks, but it won't really rev like it should, it sounds like it's missing pretty bad.

    Doesn't matter if it's choked or not. Pulled the plug, seems like it should be, maybe a bit wet?

    Any ideas?

  6. #5
    Registered User Array emaxx's Avatar
    Join Date
    Feb 2005
    Location
    Aldergrove
    Bike
    Prev. FJ600/Current Raptor 660
    When is the last time the carb came off for a good cleaning? Maybe your float is jamming up and flooding it out. Is the throttle responsive (on quick snaps) or does it kinda just revv up and revv down? Did you try a new plug. Or at least clean the old one with some emery cloth?

    Might be best to bring it in for a carb overhaul. If its firing and running I doubt its electrical. Might need someone with more experience to help you out.

  7. #6
    Registered User Array
    Join Date
    Apr 2006
    Location
    Peachland, BC
    Bike
    1981 Honda CM400
    Alright, got it running again on Sunday

    Cleaned out the spark arrestor, took off the carb and gave it a good cleaning. Changed the plug out with a new one.

    I have a feeling it was probably just the plug
    Should have listened to you guys right off the bat

    What is it that causes plug fouling? If this keeps happening, be nice to know a solution.

    Thanks again

  8. #7
    Registered User Array emaxx's Avatar
    Join Date
    Feb 2005
    Location
    Aldergrove
    Bike
    Prev. FJ600/Current Raptor 660
    They don't make things like the used to!

    Plugs are a funny thing...if you ever go through a drag race pit (NHRA) ask the guys rebuilding the engine why they always mark the plugs and which cylinders they came from. Its because when the get a good plug they want to keep it! They use it in the exact same cylinder everytime, until it craps out. When they put in a new plug they never know what they are going to get for performance. New plugs fail.

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