Help reading my plugs
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Stellar HDF Member
Joined: Apr 2007
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From: The 9th Island
Help reading my plugs
I am on-call this weekend and pretty much house bound for a few days so I figured it was time to work on the bike.
A few months ago I replaced my H-D Big Sucker for a Ventilator and thought my bike was running hot since. I called Fuel Moto and got a bit richer map. But before I loaded the new map I got some pictures of my plug from my rear cylinder. These plugs have been in the bike for the last 7K miles or so.
A few months ago I replaced my H-D Big Sucker for a Ventilator and thought my bike was running hot since. I called Fuel Moto and got a bit richer map. But before I loaded the new map I got some pictures of my plug from my rear cylinder. These plugs have been in the bike for the last 7K miles or so.
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Stellar HDF Member
Joined: Apr 2007
Posts: 2,347
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From: The 9th Island
I have had this setup for over a year and it has been fine. After I installed it, I had a local guy just do a Dyno run on it to see how it was and he mentioned that it was pretty spot on so I just left it with the canned map from Jamie.
But as I mentioned the bike seems to be running hotter after replacing my air cleaner a month or so ago. With our summer coming, I wanted to get a handle on it before it got to 100+ degree days.
But as I mentioned the bike seems to be running hotter after replacing my air cleaner a month or so ago. With our summer coming, I wanted to get a handle on it before it got to 100+ degree days.
Tourer
Joined: Dec 2009
Posts: 440
Likes: 7
From: wisconsin
That should be the other way around. It should be cooler.Call jamie and tell him whats going on. He can tweak the map.Air and fuel mixture is off.plugs look spotted with carbon deposit. Are you thinking that plug is running lean. Ive seen alot worse. Lean is mean .
HDF Community Team
Joined: Jun 2006
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From: san antonio
What is the heat range of the plug? Three things to look at; ground strap, base ring and the porcelain insulator.
The ground strap is the "tell" to gauge the correctness of the heat range. I can't see the ground strap well enough to read it but there should be a color change (light to dark) somewhere on the ground strap which will reveal the presence or lack of heat. If the heat range is correct, the color will change about half way on the strap. If the color change is near the end of the ground strap (the end above the electrode) the heat range is too cold. If the color change occurs closer to the base ring, the heat range is too hot. I would guess you need to go up a heat range because I cannot detect a color change on the ground strap but, like I said, I can't really see it.
The base ring (last thread ring) will reveal a lean/rich condition. The black base ring indicates a rich condition.
The porcelain insulator will reveal preignition or detonation. I can't get a good look at the insulator in the photos. You need to get a magnifying glass and look at the insulator under good light. If you see little specks of black or shiny specs (aluminum) that have fused to the porcelain, those are early signs of detonation and an indicator that timing adjustments should be made. Do not use the porcelain to read jetting; look at the base ring.
It is challenging to read plugs from a couple of photos but that's what I see. Closer examination using magnification and good light would reveal more. Get it on a dyno with a fresh set of plugs and get the engine tuned and then read the plugs. A canned map just isn't good enough. JMHO
The ground strap is the "tell" to gauge the correctness of the heat range. I can't see the ground strap well enough to read it but there should be a color change (light to dark) somewhere on the ground strap which will reveal the presence or lack of heat. If the heat range is correct, the color will change about half way on the strap. If the color change is near the end of the ground strap (the end above the electrode) the heat range is too cold. If the color change occurs closer to the base ring, the heat range is too hot. I would guess you need to go up a heat range because I cannot detect a color change on the ground strap but, like I said, I can't really see it.
The base ring (last thread ring) will reveal a lean/rich condition. The black base ring indicates a rich condition.
The porcelain insulator will reveal preignition or detonation. I can't get a good look at the insulator in the photos. You need to get a magnifying glass and look at the insulator under good light. If you see little specks of black or shiny specs (aluminum) that have fused to the porcelain, those are early signs of detonation and an indicator that timing adjustments should be made. Do not use the porcelain to read jetting; look at the base ring.
It is challenging to read plugs from a couple of photos but that's what I see. Closer examination using magnification and good light would reveal more. Get it on a dyno with a fresh set of plugs and get the engine tuned and then read the plugs. A canned map just isn't good enough. JMHO
Last edited by djl; Feb 12, 2012 at 11:25 AM.
Outstanding HDF Member
Joined: Oct 2007
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plugs look fairly rich but hard to tell what you were doing just before pulling them. If it was idleing for a while it could be rich at idle. with todays fuel it is hard to read plugs.
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Elite HDF Member
Joined: Jun 2008
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From: Connecticut
truthfully the only way to get a good reading on plugs is to run it click it off at speed and coast to a stop and pull the plugs. then you will see what the motor is doing. this should also be done with new plugs not ones that have run for a while. It is an expenceive way to tune a bike today
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HDF Community Team
Joined: Jun 2006
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From: san antonio
It is true that to accurately read a plug to determine it's state of tune is by performing plug "cuts" with new plugs. Put a new set of plus in, get the engine up to operating temp and to get a WOT read at a certain rpm range, open the throttle and kill the engine when you hit the target rpm range and pull the plugs. Put in another new set and check at midrange and so on; same with idle. Take several sets of new plugs with you, check where you want to check via throttle position/rpm, etc., tag and bag and read them when you get home. Reading plugs accurately requires really good light and magnification.
However, you can tell a lot by reading radnomly pulled plugs, as you have done, and checking the three elements previously mentioned; ground strap, base ring and insulator. If you do plug cuts, you can read gauge the A/F mix by reading the insulator, unlike the photos. If you want to get into the techncal weeds, there are three parts of the insulator to read; the nose, the middle and the part of the insulator that cannot be seen without light. The nose for the idle position, the middle for the pilot jet and the very end of the insulator up inside for WOT. This type of reading has more value for the race track than the street.
BTW, what is the plug gap in the photos? It might be the angle but it looks a bit wide. Can you identify the "fuzzy" stuff on the ground strap, base ring and insulator? Could it be aluminum? What does the front plug look like? The rear cylinder usually runs hotter than the front. Might be time to run a compression test just to see how the top end is holding up?
However, you can tell a lot by reading radnomly pulled plugs, as you have done, and checking the three elements previously mentioned; ground strap, base ring and insulator. If you do plug cuts, you can read gauge the A/F mix by reading the insulator, unlike the photos. If you want to get into the techncal weeds, there are three parts of the insulator to read; the nose, the middle and the part of the insulator that cannot be seen without light. The nose for the idle position, the middle for the pilot jet and the very end of the insulator up inside for WOT. This type of reading has more value for the race track than the street.
BTW, what is the plug gap in the photos? It might be the angle but it looks a bit wide. Can you identify the "fuzzy" stuff on the ground strap, base ring and insulator? Could it be aluminum? What does the front plug look like? The rear cylinder usually runs hotter than the front. Might be time to run a compression test just to see how the top end is holding up?
Last edited by djl; Feb 13, 2012 at 03:14 PM.
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