Spark plug reading
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Intermediate
Joined: Dec 2008
Posts: 40
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From: Aledo, Texas
Spark plug reading
I ride a 2012 FLHTK. I have installed a .255 cam, a SE heavy breather, and Reinhart Extreme Racing True Duals with the 4" Reinhart slip-ons. I also have the FP3. Today for s and g's, I pulled the plugs to see how they were burning. The FP is set up exactly as instructed by Vance and Hines. The front plug looked great but IMHO the rear plug appeared to be running too lean. Is there a way to just enrich the rear cylinder only. I doubt that but though I'd ask anyway. And what would y'all do if this were yours.
Road Warrior
Joined: Mar 2013
Posts: 1,923
Likes: 587
From: Alorton, Illinois
I'd do a proper plug check. Meaning, if bike was parked and you decided to look at plugs. All you really saw was what the plugs are showing last running condition. Did it idle as you opened up garage to put away?
Run it WOT and kill ignition and pull in clutch. Pull over and pull plugs. Ride steady state cruise. Kill ignition and pull clutch.......
What can be done? Don't know if FP3 has an offset? Target a richer mixture or map VE's in open loop.
If you have a bursting bomb. SFMF
Run it WOT and kill ignition and pull in clutch. Pull over and pull plugs. Ride steady state cruise. Kill ignition and pull clutch.......
What can be done? Don't know if FP3 has an offset? Target a richer mixture or map VE's in open loop.
If you have a bursting bomb. SFMF
Stellar HDF Member
Joined: Sep 2009
Posts: 2,114
Likes: 666
Just to toss a monkey wrench into this, since we no longer have lead in our fuel the leading cause for coloration to the porcelain is no longer present.
The only way to accurately read spark plugs run with unleaded fuel is by using an otoscope like the one your doctor uses to look into your ears.
There will be a fine-line color ring found at the very bottom of the porcelain insulator.
Proper plug reading is not something that can be done in the garage...as Jason explained.
You must start with a new set of plugs, run the bike @ WOT for at least a couple miles, then clutch in and ignition cut. Stop by the side of the road and remove the plugs and take a reading as explained above.
Then another new set of plugs to be run for a few miles at steady-state cruise rpms/speeds.
Repeat the "clean cut" procedure explained above and take your readings.
If this sounds like a real PITA to get a reading, you are right and I never suggest or rely on plugs reading to tune an EFI bike because there are some 175 tune points per cyclinder and you need to know exactly where you are to make changes that will provide expected results.
Dyno tuning allows the tuner to test and tune all these points very accurately whereas trying to figure what you need to do and where to do it on the street is very difficult at best without at least recorded logs to identify exactly where the change needs to be...as well as how much change is necessary to correct the running issue(s).
Bob
The only way to accurately read spark plugs run with unleaded fuel is by using an otoscope like the one your doctor uses to look into your ears.
There will be a fine-line color ring found at the very bottom of the porcelain insulator.
Proper plug reading is not something that can be done in the garage...as Jason explained.
You must start with a new set of plugs, run the bike @ WOT for at least a couple miles, then clutch in and ignition cut. Stop by the side of the road and remove the plugs and take a reading as explained above.
Then another new set of plugs to be run for a few miles at steady-state cruise rpms/speeds.
Repeat the "clean cut" procedure explained above and take your readings.
If this sounds like a real PITA to get a reading, you are right and I never suggest or rely on plugs reading to tune an EFI bike because there are some 175 tune points per cyclinder and you need to know exactly where you are to make changes that will provide expected results.
Dyno tuning allows the tuner to test and tune all these points very accurately whereas trying to figure what you need to do and where to do it on the street is very difficult at best without at least recorded logs to identify exactly where the change needs to be...as well as how much change is necessary to correct the running issue(s).
Bob
Intermediate
Joined: Aug 2016
Posts: 43
Likes: 4
From: Mantua NJ
Just to toss a monkey wrench into this, since we no longer have lead in our fuel the leading cause for coloration to the porcelain is no longer present.
The only way to accurately read spark plugs run with unleaded fuel is by using an otoscope like the one your doctor uses to look into your ears.
There will be a fine-line color ring found at the very bottom of the porcelain insulator.
Proper plug reading is not something that can be done in the garage...as Jason explained.
You must start with a new set of plugs, run the bike @ WOT for at least a couple miles, then clutch in and ignition cut. Stop by the side of the road and remove the plugs and take a reading as explained above.
Then another new set of plugs to be run for a few miles at steady-state cruise rpms/speeds.
Repeat the "clean cut" procedure explained above and take your readings.
If this sounds like a real PITA to get a reading, you are right and I never suggest or rely on plugs reading to tune an EFI bike because there are some 175 tune points per cyclinder and you need to know exactly where you are to make changes that will provide expected results.
Dyno tuning allows the tuner to test and tune all these points very accurately whereas trying to figure what you need to do and where to do it on the street is very difficult at best without at least recorded logs to identify exactly where the change needs to be...as well as how much change is necessary to correct the running issue(s).
Bob
The only way to accurately read spark plugs run with unleaded fuel is by using an otoscope like the one your doctor uses to look into your ears.
There will be a fine-line color ring found at the very bottom of the porcelain insulator.
Proper plug reading is not something that can be done in the garage...as Jason explained.
You must start with a new set of plugs, run the bike @ WOT for at least a couple miles, then clutch in and ignition cut. Stop by the side of the road and remove the plugs and take a reading as explained above.
Then another new set of plugs to be run for a few miles at steady-state cruise rpms/speeds.
Repeat the "clean cut" procedure explained above and take your readings.
If this sounds like a real PITA to get a reading, you are right and I never suggest or rely on plugs reading to tune an EFI bike because there are some 175 tune points per cyclinder and you need to know exactly where you are to make changes that will provide expected results.
Dyno tuning allows the tuner to test and tune all these points very accurately whereas trying to figure what you need to do and where to do it on the street is very difficult at best without at least recorded logs to identify exactly where the change needs to be...as well as how much change is necessary to correct the running issue(s).
Bob
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