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Is there a plug for weak spark?

Discussion in 'Other Motorcycles' started by dmx_xs400L, Jul 19, 2009.

  1. dmx_xs400L

    dmx_xs400L Member

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    This might be a stupid question, but my XS400L seems to have a weak spark.
    So why wouldn't some different spark plug give a stronger spark with the same voltage? 8O
     
    dmx_xs400L, Jul 19, 2009
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  2. 650boy

    650boy Member

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    They wont give a "stronger" spark . Use whats recommended in the owners manual its prob a b7es ngk.. weak spark can also be cause by a worn or defective ignition coil.. but replace the spark plug first its cheaper...
     
    650boy, Jul 20, 2009
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  3. dmx_xs400L

    dmx_xs400L Member

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    it's a D8ES ngk in fact.
    I have 3 sets of new spark plugs and I keep trying new plugs :lol: - ignition coils are new, so is the starter switch in fact. I've been suspecting the TCI for a long time.
     
    dmx_xs400L, Jul 20, 2009
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  4. tylernt

    tylernt Member

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    Make sure you don't have "resistor" plugs (they often have an 'R' in the code). Aside from that, you can set the gap at the smaller end of the spec.
     
    tylernt, Jul 20, 2009
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  5. bill

    bill Active Member

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    What makes you believe you have week spark? Also I have an ignition unit from an 82 XS400J not sure if it's the same I would have to look up the numbers. Anyway if it comes to that it may help.
     
    bill, Jul 20, 2009
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  6. dmx_xs400L

    dmx_xs400L Member

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    Been waiting, hoping to hear news that Bill would come back some time to take my response to his post. Sadly it's all over for Bill. Rams in the fact that riding is dangerous, even for those who are careful about it.

    Tylernt... I was asking myself that same question: making the gap smaller on the plug should help the spark, shouldn't it. Nice to have confirmation. Tks.

    Anyway, since the time I have this problem with one cylinder lacking pressure, to get to start the bike I rev it up to 6000 rpm. After I read someone who was explaining the alternator on this bike was "self igniting" or "self actuating", I don't remember his words, and needed a visit to 4000 rpm to get going, I decided to rev up the engine at startup - just a few seconds over 4000 rpm.

    The engine used to quit 2 or 3 times after first startup before holding on - then it was ok for the day. Now, when I rev it up over 4000 to 6000 rpm a few seconds (3 seconds maybe?), with no choke, then put on the choke for a couple of minutes, it seems fine. No longer quits on me. Seems I found a cure.

    So I guess the TCI might be ok (thanks for the offer of a TCI Bill!), but the alternator needed to be kicked in to generate enough current to ignite the spark plugs regularly... not sure: just a guess. Hope I have found a solution to this "weak spark" (as stated by a mechanic) problem.

    October 19th edit to my august post: Solution to startup problems still working. Bike now winterized. Will look in to changing a valve next spring.
     
    dmx_xs400L, Aug 5, 2009
    #6

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