Confusing Spark Plugs
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6th Gear
Joined: May 2005
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Confusing Spark Plugs
Over the last few weeks i have notised a miss or a cough in the mid range and idle, on my 05 twin cam softail. i jut had the dealer install V&H side shots with a jet kit and a mass air flow kit from S-Eagle. soon as i got it back i removed the baffles. so i thought that the problem was that it needed to be rejetted. i was a about to do so my self but i decided to check the spark plugs to make sure. i pulled the rear cylinder and found it was a dryed black and sooted to the point that it was almost fouled? so now im thinking that it is to rich. i pulled the front and it had a chalky white eletrode and a grey ground eletrode? so now i don't know what to think? hear is my thoughts about this. the pipes would be classifide as shorty drags with a cross-over and being that the rear pipe is so short it is geting a bad revresle that is puting exhaust gasses back in the cylinder causing the black plug but i still think it needs to be rejetted becouse of the white plug and the free flow of the pipes. i think that bigger jets and a set of tork tubes might fix this. but would like to hear anyones thoughts about this problem becouse im just taking a shot in the dark on trying to diganose it.
Seasoned HDF Member
Joined: Dec 2004
Posts: 7,934
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From: Bloomfield, NM
RE: Confusing Spark Plugs
Your front plug sounds just about right. If there is no glazing on it, it is probably alright. The rear could be the result of the pipes like you said, or a bad plug. A bad plug that is not firing hot enough could cause a rich condition.
Regards,
Bill
Regards,
Bill
Seasoned HDF Member
Joined: Jan 2005
Posts: 21,949
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From: My house
RE: Confusing Spark Plugs
It could be a bad plug like Bill said, and I would put the baffles back in or make some lollipops, to replace them with, you need some back pressure on that motor.
The other thing I would do besides taking it back to the dealer while it's under warranty, is if they have a dyno or if they don't, find one and have a dyno base run to check the AFR (Air Fuel Ratio), the readout from the dyno's exhaust sniffer will give you an accurate account at all load ranges on whether you're too lean or too rich in any rpm area's, and you get a HP/torgue reading at the same time.
Nowadays with the fuel we burn you can't get accurate plug readings due to the oxidizers and detergents required by the EPA. Keep us posted on how you end up.
Good luck
John TN
The other thing I would do besides taking it back to the dealer while it's under warranty, is if they have a dyno or if they don't, find one and have a dyno base run to check the AFR (Air Fuel Ratio), the readout from the dyno's exhaust sniffer will give you an accurate account at all load ranges on whether you're too lean or too rich in any rpm area's, and you get a HP/torgue reading at the same time.
Nowadays with the fuel we burn you can't get accurate plug readings due to the oxidizers and detergents required by the EPA. Keep us posted on how you end up.
Good luck
John TN
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6th Gear
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RE: Confusing Spark Plugs
thanks for the info bill. i put a set of exoust cones in and a set of auto light plugs it help it out a good bit, but its still thare a little. so im just going it have a bike shop take a look at it. i was told that it could have been jetted wrong from the dealer. so thanks for the help Bill.
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