kickin,spitin,and backfiring.

Discussion in 'Electrical' started by bus driver, Mar 16, 2012.

  1. bus driver

    bus driver Member

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    I have a stock 91 EGC with the 1340 EVO. The other day out of the blue my bike started to kick,spit, and backfire. I didn't have time to check it out yet but I figured I'd ask you guys first for some ideas. It has 23,000 miles on it. I was able to nurse it home from around the corner, but it wasn't cooperating. It seem like a intermittent ignition problem. It would develop normal power and then act up. It was constantly going back and forth between normal power and misfiring. (quickly). When it lost power the tach would lose power so it seemed. (fall towards zero like it lost it's electrical sorce) . When I got it home I moved the plug wires to see if maybe it was grounding out and the #2 wire gave me a "little" ZAP. I tried moving the wires around to see any arching but I didn't see any in the dark. I had the plugs out the other day and they looked great. I rebuilt the carb last year. The wires were on nice and tight. I,m not sure if wires would cause that type of problem, but I don't know. I bought the bike 2 years ago and never tuned it. Never had to. 43mpg and clean plugs. I suspect coil, but i don't know. I hate spending good money after bad. any help would be greatly appreciated. I also always run Sea Foam. Ride Safe. Bus Driver.
     
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    If you got bit by the plug wire, I would bet that there is a break in the insulation cover (probably facing the engine so it is no easy to spot) or the boot where it is grounding out. I had this exact problem on my '91 where the plug wire boot came out of the coil cover plate. There was a very small hole through the bottom insulation boot grounding the spark to that plug intermittently.

    If you haven't replaced the plug wires for a while, try that as your first and easiest fix. If it works, great. If not, it is good PM anyway.

    Let us know.

    TQ
     

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    Last edited: Mar 16, 2012
  3. BUBBIE

    BUBBIE Well-Known Member

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    That is where I would start also.

    The 97 EVO i had had BOTH problems with the Crank sensor and the Cam sensor…

    IF you want to check IF the new plug wires don't do the correction,

    I'd CHECK the sensors,,,,, They do about the same type of Symptoms.(missing and stuttering)

    BUT,,,,JUST Cost More$$$$$$.. Check, don't toss money at the problem is a good Idea...

    signed....BUBBIE
     
  4. Jack Klarich

    Jack Klarich Expert Member

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    Replace the wires first, use a spat bottle and mist some water on the coil with the engine running to check for a hair line crack, check the pick up wire coming out of the nose cone is not brittle and rubbed through, I assume this is stock ignition?
     
  5. bus driver

    bus driver Member

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    Thanx guys. I exchanged the plug, wires, and coil with my friends evo(same year)no luck .I discovered rust in the tank though. Any suggestions on how to clean a rusty tank? I rebuilt the carb last year so taking it apart again should be easy. Tha plugs seemed to be alittle rich. I was thinking maybe muriotic acid for the tank. How much I don't know. I tried misting water around the coil, wires,and plugs to see any arching, there was none. any advice would be appreciated. Thanx Bus Driver.
     
  6. Hoople

    Hoople Account Removed

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    It does sound like an ignition problem. At this time, does the bike start and run ok. If it runs ok, is it temp related. If I am not mistaken, that engine has a nose-cone hall effect switch for ignition trigger as Jack suggested.

    The closest diagram I have is for a 1990. Verify you have solid battery power on the coil stud that has the white wires going to it. That stud with the white wires is the power source for the coil and the ignition module. If your good there, I would focus on the nose cone trigger electronic pickup.

    Not your exact year but this may be what you have. Bottom right is an overall view of the complete ignition system. Beginning with the power source (white wire going to coil),, 3 wire Hall trigger/timing unit,, ignition module,,, VOE (timing advance switch) and the single primary (dual fire) coil.
     

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  7. bus driver

    bus driver Member

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    I checked the v.o.e.s. and that's ok. I swapped the coil, wires and plugs (known to be ok). Ran new gas. Is the nose cone trigger unit also known as the sensor plate? I have a Harley shop manual. Running cold or hot didn't matter. Thanx bus driver. P.S. I'm going to clean the carb now just for the heck of it. There was rust in the tank.
     
  8. Hoople

    Hoople Account Removed

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    Yes. It's called that in the manuals I have.
     
  9. bus driver

    bus driver Member

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    Two things, While I had the carb apart I found the float needle rubber end not attached to the needle. That could explain the random bowl over flow. Also since the opinion was that it was the nose cone trigger, I investigated. While jiggling the wire for the sensor I discovered at a certain spot in the wire the bike would die. It was where a tie wrap put a 90 degree in the wire and the covering (not the insulation) was worn though. Tomorrow I am going to try soldering some new wire where I suspect the breakage. I really hope it gets me back on the road. The weather is just starting to break and all of my friends wave as they ride by.(bye) Thanx for all of the help .Bus Driver P.S. it always sounded like ignition to me, not fuel, but I was looking at everything. Thanx
     
  10. bus driver

    bus driver Member

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    Sometimes you get the eleavator and sometimes you get the shaft. Today I got the eleavator. All it was, was a broken wire to the nose cone trigger. Thanx guys for pointing me in the right direction. you were a life saver. Plus a ton of money. While I was playing, I drilled out the idle mixture screw plug and was able to adjust the mixture. It's 21 years old and runs like new. Back on the road again, what feeling. Thanx again guys.Ride safe. Bus Driver.