spark plug gap
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4th Gear
Joined: Feb 2014
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From: Ennis
spark plug gap
I have an 09 nightster 1200 i changed the plugs and set them at .040 like harley said and it started backfire sounds like from the intake and misfiring so i set it ar .032 and it runs a little smoother was wondering if i need to go lower or does anybody no what the problem is at idle it sounds good just going from first to second or low rpms
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From: Niles Canyon Ca.
Tourer
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From: Florida
The difference in those plug gaps shouldn't make a giant difference for you - like nytrydr said you may have a wire off or crossed. Make sure your wires aren't arcing - if some of the shielding is/are cut and arcing.
reasonable man theory applies here....if applicable
reasonable man theory applies here....if applicable
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Joined: Mar 2009
Posts: 66,115
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From: Niles Canyon Ca.
Ok guys think about this a second how can you cross the wires when both holes on the coil fire at the same time ?
Answer : it doesn't make a damn bit of difference if you swap them on a dual fire ignitions system .
Op set the plugs at .040" like the book says and try again , plug gap on the electronic ignition systems run bigger not smaller only reason you'd close the gap is MUCH higher compression or you're playing with the timing some . NOT for the novice to do.
Answer : it doesn't make a damn bit of difference if you swap them on a dual fire ignitions system .
Op set the plugs at .040" like the book says and try again , plug gap on the electronic ignition systems run bigger not smaller only reason you'd close the gap is MUCH higher compression or you're playing with the timing some . NOT for the novice to do.
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Joined: Jun 2014
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From: Florida
Dude - increasing your plug gap to .040 will raise your compression ratio alot. Really?
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Road Warrior
Joined: Nov 2010
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From: Jacksonville, FL
Read TwiZted Biker's post again... He did NOT say that changing the gap would raise the compression. He said the only reason you would close the gap would be IF it was a high compression engine.
Last edited by edpnjax; Jun 21, 2014 at 12:14 PM. Reason: Spelling & correct mistake
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From: Boynton Beach, FloriDuh
Ok guys think about this a second how can you cross the wires when both holes on the coil fire at the same time ?
Answer : it doesn't make a damn bit of difference if you swap them on a dual fire ignitions system .
Op set the plugs at .040" like the book says and try again , plug gap on the electronic ignition systems run bigger not smaller only reason you'd close the gap is MUCH higher compression or you're playing with the timing some . NOT for the novice to do.
Answer : it doesn't make a damn bit of difference if you swap them on a dual fire ignitions system .
Op set the plugs at .040" like the book says and try again , plug gap on the electronic ignition systems run bigger not smaller only reason you'd close the gap is MUCH higher compression or you're playing with the timing some . NOT for the novice to do.
No, it will not run with crossed wires.
Edit to add:
During start-up "cranking" (<~500 RPM), Harley single fire ignitions operate in dual-fire mode until the ICM/ECM can determine where the 2 pistons are in their cycle in relation to the single crank position sensor pulse for that cycle, and then it switches to single fire. With crossed wires the motor may sputter while cranking at low RPM, but as it starts to catch and builds RPM, it will die when as switches into single fire mode before reaching normal idle RPM.
Last edited by cHarley; Jun 21, 2014 at 11:44 AM.