check plugs to see if running rich or lean with efi
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Road Warrior
Joined: Oct 2009
Posts: 1,317
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From: Texas
check plugs to see if running rich or lean with efi
I friend of mine is running a 12 dyna and his tune is lean. He wanted to pull plugs and check to see how lean.
I remember last year I wanted to do same thing after my stage 1 upgrade because mine was running lean and the shop I purchased my stage 1 from said looking at plugs wont tell them anything if using an efi system. ??? Any truth to this? Doesnt sound very logical to me but stranger things have happened.
I remember last year I wanted to do same thing after my stage 1 upgrade because mine was running lean and the shop I purchased my stage 1 from said looking at plugs wont tell them anything if using an efi system. ??? Any truth to this? Doesnt sound very logical to me but stranger things have happened.
Ultimate HDF Member
Joined: Aug 2012
Posts: 6,470
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From: on the road
reading plugs is kind of a guessing game ------------on regular automotive you can't get a good read without killing the engine at higher rpm.If you idle your efi harley a bunch you will see a similar thing. so don't let a fat idle fool you.All of my efi buddies guess using the plugs until they can get to a dyno
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Road Warrior
Joined: Oct 2009
Posts: 1,317
Likes: 16
From: Texas
If a bike is running lean wouldn't the plugs display the tips as white or very light whether efi or carb? and im talking about just pulling plugs and looking them over when bike is cooled down.
On my old carbed softail black sooty plugs where an indication of running too rich and white was too lean. Has that changed with efi?
On my old carbed softail black sooty plugs where an indication of running too rich and white was too lean. Has that changed with efi?
Unofficial HDF Chaplain
Joined: Dec 2009
Posts: 21,136
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From: san diego
agreed!! remember efi also has o2 sensors that will drive the ecu in one direction or the other along with other sensors (map) that change air/fuel ratio up to the point of throwing a check engine light. so you can have a rich running bike that the ecu is trying to lean out and can't tell by looking at the plug. air/fuel ratio, or a co/hydrocarbon reading is the only way to get the mixture right. there are symptoms from mixture problems KBFXDI gave some of the lean ones rich settings will be poor acceleration, bad mileage ect. don't try to use what used to work for a carbed bike they are different. yes very white is lean and black is rich, but how it happens and how it gets there is different
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Unofficial HDF Chaplain
Joined: Dec 2009
Posts: 21,136
Likes: 18,046
From: san diego
if you were to compare plugs on a good running efi bike vs a good running carbed bike, the efi bike would look very lean
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