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? asked in Cars & TransportationMotorcycles · 1 decade ago

my motorcycle is only firing on one cylinder....why?

pretty much what the title says. i have replaced the plugs and plug wires but theres been no change. ive just really got no clue where to go from here.

Update:

the plugs were gaped and there its a spark with the new line, carb and fuel lines are clear and clean. how would i go about checking/ changing the timing?

Update 2:

sorry, earlier i was in a rush and was very vauge. the bike is a 1986 harley davidson sportster 883. the battery is new and all of the connections in with the ignition seem to be fine.

7 Answers

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  • Jon
    Lv 7
    1 decade ago
    Favorite Answer

    Pretty vague question...we dont even know what kind of bike you have. It could be a million different things, from a bad battery, to an internal motor problem. DETAILS make all the difference in getting good answers.

    Your first step to finding out the problem, is getting the service manual, and step by step do the troubleshooting tree for the ignition system.

    Source(s): Honda & Suzuki Service Technician Graduate of MMI (Motorcycle Mechanics Institute) Phoenix Az. 25+ years riding experience
  • cindie
    6 years ago

    hello I have a 2011 xl 883 l one day it just started running ruff and backfiring, have had 2 people look at it, cant figure out whats going on with it, new battery, new plugs, new sparkplugs, drained tank thinking it was bad gas, not the case. it is not firing on rear cylinder and as of today it was running then stopped and now wont start. frustrated here for sure, any help on how to fix this problem, riding season is slipping away. its been down for 5 weeks now.

  • theharleyfixer
    Lv 5
    1 decade ago

    STILL need more info...

    What ignition system is on the bike, stock or aftermarket, single or dual fire?

    Older stock Harley ignitions are dual fire and fire both plugs together, if its stock and you are only getting fire on one cylinder, its time for a complete new ignition, this was a common problem.

    Look into Daytona Twin Tec, get their complete sytem, module, coils and wires, get their VOES vacuum advance switch and follow the instruction for installation, its easy and can be done in less than 2 hours

    Source(s): Master Tech and Engine Builder
  • Esoteric
    1 decade ago

    To test to see if you have a spark hold the spark plug against the engine with the HT lead attached and turn the engine over.(It will need to be fairly dark to see the spark)

    Check the fuel lines, blow down them towards the carburetor as the there could be a blockage and the carburetor could be blocked up in some way. It may need cleaning out.

    Check valve clearances as the timing could be out.

    http://a.imageshack.us/img231/6212/gifninjas.gif

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  • Adam
    1 decade ago

    with the new plugs you might have to gap them using a feeler guage, the distance for the spark to travel might be slightly too far

  • Bob A
    Lv 7
    1 decade ago

    I agree with Jon there's not enough information to go on.We need basics Year Make and Model.

    Source(s): 35yrs lic mech 40+ yrs riding
  • Anonymous
    1 decade ago

    It's a single?

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