Vance Hines 2 to one comp and Fuelpak slight backfire than after sparkplug change lower rpm and worst backfire? 35 gap. Any recommendations? Advice?
Spark plugs and gap
Harshbarger
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Vance Hines 2 to one comp and Fuelpak slight backfire than after sparkplug change lower rpm and worst backfire? 35 gap. Any recommendations? Advice?
This is not spark plug related but more of a fuel issue. Fueling changes with a higher engine temp and air temp, which leans the mixture some. This adjustment is normal. You might have been in that zone when experiencing the popping. Plugs, .035 gap and stay with stock plugs. No gain to go with other brands but you can screw up the ion sensing (knock control) if another brand has resistance values out of spec. If the popping persists, a tad richer mixture in the low end should reduce or eliminate it.
Ron
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I switched to NGK Iridium plugs, which are supposed to be more fuel efficient and a more surefire spark. I am bringing it in for a dyno tune to optimize it. It should scream without missing a beat. I can't wait. Results TBD. The guy that is doing the dyno is one of the country's best, which is a huge plus. I would suggest bring it to someone who does this to optimize your power and fuel efficiency in conjuction with a Powercommander. I am using a Powercommander III USB since it came with the bike when I bought it. I hope yours came out OK. Cheers.
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Also sticking with the factory recommended gap of .035. Just thought I would add that.
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Be careful. There have been quite a few cases of the NGK Irridium plugs stopping the ION sensing from functioning correctly as Ron mentioned in his post above.
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It's weird that the resistance value would be different on a plug that's supposed to be a direct replacement (cross-referenced) for the stock plugs. I wish there were a way to compare them test-wise, because NGK is supposed to be supreme quality, and made in the US. I will take heed though and switch them out for the double platinum ones of the HD version just in case. I believe quality makes a difference if there is one, which is what I believe in. Thanks man.
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Tim-
This is actually incredibly common in the parts industry. Romeo, HD does not make sparkplugs. NGK, Denso, Bosch, Autolote... they make plugs to OE specs. They also will list them as a replacement part for other engines, and while they “fit” sometimes due to other system differences like coil firing KV, primary winding current draw, etc. they don’t function as well as the OE. The most notorious example was where Chrysler engines didn’t like anything but champion plugs.
This is actually incredibly common in the parts industry. Romeo, HD does not make sparkplugs. NGK, Denso, Bosch, Autolote... they make plugs to OE specs. They also will list them as a replacement part for other engines, and while they “fit” sometimes due to other system differences like coil firing KV, primary winding current draw, etc. they don’t function as well as the OE. The most notorious example was where Chrysler engines didn’t like anything but champion plugs.
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Thanks Ron. I will take that advice. The guy that will be performing my dyno tune will do it justice, with the OEM plugs.
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These are all interesting answers and great discussion. Thanks!
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