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Reversed Ignition Coil Wiring

Submitted by les_waller on Mon, 17/10/2022
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Commando

I am in the process of resuscitating 1971 bike which, when I acquired it, hadn't run for about 3 years although was running when put away. As the PO is my brother in law I believe this to be true. I haven't touched the engine internals and I have sparks at the plugs which get appropriately wet when I crank the engine using my paddock starter. However the engine will not run apart from an occasional backfire.

Whilst working on the bike I replaced the wiring harness as the original one had been attacked by mice. I believe that I have replaced the harness correctly as all the lights and switches work correctly. However I am  wondering if I have inadvertently reversed the LT feeds to the ignition coils. I.E. LT wire 1 is going to coil 2 and vice versa. Would this prevent the engine from starting? 

If this is not the case then does anyone have any suggestions please?

Submitted by john_holmes on Mon, 17/10/2022

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What ignition do you have ?

Original points will require the correct LT to the correct coil, so swap them and start kicking again. With Electronic Ignition they are all wasted spark so it makes no difference. 

Submitted by les_waller on Mon, 17/10/2022

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Thanks John, I have the original point system so I will swop the leads and try again.

Thankfully I don't have to kick as I am using a paddock starter due to my advanced years and failing strength.

Submitted by ian_soady on Mon, 17/10/2022

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... I believe that it makes very little difference which way round they're connected. It will mean the spark is the opposite polarit but this should still work.

Submitted by eddie_cross on Mon, 17/10/2022

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Swap to new plugs? I now go with NGK. Have thrown out about 4 new/nearly new plugs due to misfires. Was on the point of pulling lots of the bike apart.

On my latest bike shipped as a non-runner from the states it seemed to take ages to figure out how much choke/tickling was required to start it and also seemed to change! Now seems to start best with full choke, and a little tickle but not so much as to come out of the carb. So maybe just trial and error.

I would also drain the float bowls and clean any crud out. Don't forget the guitar string down the idle port. Possibly clean the tank too. Check carb fuel filters. I had loads of rubbish that continually caused running and starting issues for months. I have now fitted extra glass filters under the taps as a 1st line of defence.

Cheers
Eddie

 

 

Submitted by ian_soady on Tue, 18/10/2022

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You're absolutely right I misread the original post. I thought the coil wire on one coil had been reversed. Of course if a Boyer sytem is installed the coils are in series so in this case it doesn't matter which way round they are.

Submitted by alan_osborn on Tue, 18/10/2022

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Coil wiring. If using original points then each set of points MUST be connected to its specific Ignition coil for the engine to run. If using Boyer or Pazon etc then the coils are in series so which coil fires which cylinder is irrelevant. BUT the coils need to be wired in series + to - correctly, and with the overall +- in line with the battery +-. IF the coil's +- is reversed the spark is reduced but still works.

Submitted by alan_osborn on Sat, 22/10/2022

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It's amazing how broad that grin is when the ol' girl fires up well after a non working issue.

 



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