(Edit) Note: Scroll down to post #24 for photo charts of reading spark plug conditions and additional links to much more info.

I had my motor top end rebuilt over the winter. It was bored .20 over and bumped up to 9.6:1. I started out for about 2k miles with the original carb and a seemingly leaky intake effecting the front cylinder. I replaced the carb / intake with a brand new S&S Shorty Super E and put in new plugs. Now about 2K later I'm trying to gauge what's happening by the plugs. First 3 are the front cylinder, and the last is the rear one.


I'm confused on how they could look so different. Both were changed new with the carb/intake replacement. Also not sure why the front plug has a specific burn mark in the insulator and front of the tip, and the threads are all carbon-ed up. I did notice the front plug was hard to extract today while cold, possibly from the carboned threads, and the rear spun out easily. I have put spark plug antiseize on the threads.

But that one black mark in the insulator near the tip, the tip and the threads has shown on all the plugs, before and after the carb / intake change.

Do I need to use two types of heat range plugs because the back cylinder is much hotter?

The new carb is a lot different in warm up. Once it's hot it idles perfect. On warm up I adjust the enricher from wide open at start, and idling at almost 2k rpms, down to about 1,100 rpms and it warms up smoothly, but as soon as I move it back to no enricher it will stall, or idle at about 500 / 600 rpms. As soon as I drive a short distance the idle stays at 950 /1k perfectly. I adjusted the idle air and at 1 1/4 turns it's a 1/4 turn up from rough idle when hot. And if you hit 1 3/4 it begins to be rough again, seem like it's slow jetted perfectly. The power and snap quick acceleration is very good and I've had no issues, only lots of power. Feels like a whole new bike!!!

So why am I seeing these distinct marks on the front and a too lean on the back?

(Edit) Note: I've concluded that the bad carb and poorly sealing intake during the critical break in process may have contributed to the rings not seating correctly and the front plug (first 3 photos) appears to have oil deposits on it from an issue with the top ring gap and break in. The last photo appears that there is oil leaking past the rings causing the white debris during the ignition stage.

My consideration for a cure is to hone the cylinders and put in a fresh set of rings. This will depend on the condition when disassembled.

For now I'm going to closely monitor the oil use and keep fresh plugs in it more often than normally required.

Updated Summary in post 26.

 

Second plug looks like it's burning oil. That is odd that your rear plug isn't showing richer than the front, because it should be the exact opposite.

EDIT: I will say this... don't put entirely too much faith in your plug readings with this corn gas. I'm running a 46 slow and 185 main and my front and rear plugs are gray... it's almost impossible to read plugs with the trash they put in the pumps. About the only way to really know is to fill up with non-ethanol gas, and get some new plugs and try again.

 

If it is running good, put good plugs in it with some anit-seize and don't worry about it. Back jugs run hotter/leaner than front ones. Just part of the V-Twin experience.

To properly read spark plugs, you need to be moving with the engine rpm/load and throttle where you want to check it, hit the kill button, pull in the clutch and coast to the side of the road, then pull the plugs and read them.

If it is running good, put good plugs in it with some anit-seize and don't worry about it. Back jugs run hotter/leaner than front ones. Just part of the V-Twin experience.

To properly read spark plugs, you need to be moving with the engine rpm/load and throttle where you want to check it, hit the kill button, pull in the clutch and coast to the side of the road, then pull the plugs and read them.

 

I do realize for the best, most precise reading of the plugs there is an elaborate way to do so. But if a plug is in the motor for a good number of miles and it's taken out and has signs of possible issues it just can't be disregarded that the accumulated miles has caused overall issues with the plugs.

I am seeing a very slight amount of white smoke from the exhaust, especially if I give it a quick rev while sitting. I also believe I'm noting some excessive oil use but I will do a thorough fluid change and then log the miles and the addition of oil to be more thoroughly accurate about this. Since the bike is running so well this summer I have been putting a lot of miles on it compared to other years.

The top end rebuild was done by a meticulous Evo Indy and I was very easy on breaking it in during the first 1K. BUT, after that when being able to now run it a little harder I had carb issues and was making many, possibly too hard, test runs and adjustments, and fear I may have caused some damage to my freshly rebuilt top end of the motor.

I'm just trying to decide where I am on the issue. Do I "just ride it" because it runs well, or do I address matters while the engine rebuild is at about the 4K mark? I don't have unlimited funds so addressing matters before they become worse and expensive is the whole point of the matter for me. I have a summer getaway coming up and want to be certain it's in the best shape it can be in while I have a little time before touring with it.

All the information I can get and feed back is helpful and appreciated ...always!

 

Possibly leaving the enricher on too long and blacking plug.
I only use the enricher to start then immediately turn it off and use throttle to hold at 1000 rpm.
Any speckles on insulator is pinging if you can hear it or not. Higher octane and check timing. I had to ditch the VOES to get rid of ping and speckles depending on your ignition sys.

Smoking may need Cr test or leak dn test. for valves or rings.

 

Aces,

Appreciate that. I will take the enricher advice. I'm running a Crane Hi 4E external module and not certain about taking the VOES advance system out because it runs real well. I do have an adjustment on that module for varying the advance curve and the rear cylinder offset which are both in the neutral "5" setting position. Which I believe is normalized.

I can tell you that the piston manufacturer mentions you may need to retard by 2 to 4 degrees for some reason, but when talking with their tech he said that would be for a much higher performance motor including nitrous to prevent burning up the piston.

Always use 93 octane and I have the timing set precisely to the manual. But I have been concerned about the looks of those plugs having tiny debris like deposits.

Still can't figure that glossy blackening on the front plug's insulator and the tip. As you can see the sides, top and back of the tip are clear, and even the un-blackend areas of the insulator are more of a correct tan. But what is up with the pure white rear plug?

Anyone ever run two separate temperature rated plugs before on each cylinder?

Also it runs typically between 180 and 240 degrees so I know it's not overheating according to the oil temp.

Does anyone else think I should stop gambling with the setting and get it on a dynamometer so it will be tuned it completely right for performance balanced with mileage? I'm getting 38 on the throttle and 42 cruising.?

 

I have 2 guesses on that.
1) Rings not seated yet.
2) Ring gaps not set in the right place and you are getting blow by.

 

That makes some sense to me. Thanks

Leaves me a bit worried, how many miles does it take for them to seat completely?

My indy was very critical about how the rings are positioned, so I may have a seating issue. But these pistons are very close tolerance design.

 

If you run the bike normally for the first 50 miles that is all it should take to seat the rings. Babying it will just wear down your fresh crosshatching and the rings won't ever seat properly. Aggressive (not hard ***** to the wall) acceleration and engine braking is what does it.

 

you used KB pistons in the engine as the 9.6 is the tell tale to that

the plug is showing signs of not being seated OR it has galled up the wall as could have happened with e tight clearances KB pistons require

you will be pulling the front head again