hey guys i went out today to fire the bike up and take it for a spin but it wouldnt start..it would crank fine but not start. i pulled one of the plugs and held it agaist the engine for ground and cranked it but the plug is not firing, no spark at all.. i havent started the bike in about a month and i,ve never had problems before so could could it be a bad coil..if i hook the plug wire to the plug andground the plug to the engine while cranking the engine shouldnt the plug spark...thanks for any help...

 

Dave if you have the plug out of the engine the ECM knows there is no compression in that cylinder so it cuts off the injector and ignition in that cylinder......now it's a bit more complicated than I explained but you get the drift. Install the plug back in the cylinder and use another plug to test with.

 

is there anyway to test the voiltage reg. and coil to see if there bad

 

Test the spark Dave....if it sparks the ignition is not bad

 

That's kinda cool. I wonder how they do that. I was under the impression that the crank rotation (in the 720 degrees) was located by the Ion sensing. Without a plug (at least one I guess) hooked up, ion sensing would never find the compression stroke. I guess they could do this by watching the teeth on the crank with the wheel decoder but most codes that I have seen do not like to do that as a weak battery will cause havoc with the wheel decoders as the cranking speed (degree by degree) is really inconsistant and difficult to decode.

Do all late Harleys use waisted spark durring the start procedure and then convert to single spark once the motor comes to life and the Ion sensing has a lock on the crank?

still asking questions

AW

 

im going out this morning and buy new plugs and wires.. the plugs and wires are the ones that were on the bike new and they have a little over 7500 miles on them so they may need to be changed..i'll post back ...thanks

 

well i bought new plugs and wires and it fired right up...go figure..lol..im hopping that was my problem all along...anyway thanks for the advice guys