My 2010 EG Limited has a SE Stage III. No head work, SE air cleaner, V&H Exhaust. Stage III is basically 10.5 to 1 forged pistons and 259e cams. SEST.
Work done by local Harley dealer, it was not dyno'd. The motorcycle had about 15,000 miles on it when the work was done. Has run great with no problems till now, 30,000 miles. This year as the weather got hot it has started pinging pretty bad. Dealer set the timing back a couple of degrees and it ran terrible but no pinging. They put it back to where it had been and it runs great but the pinging is back. It is scheduled to go to the dealer next week but was wondering if anyone else may have had a similar issue and found a cure? I use the highest octane gas I can buy. Usually 91 or 93 it makes no difference in the pinging. What would be the cause for it to run fine for 15,000 miles and now this problem? Thanks for your help.

 

pre ignition can be the result of low octane gas, advanced ignition timing ( as you already know), also a result of sharp edges in the combustion chamber or carbon deposits acting as "glow plugs".

it could be that improper tuning has caused carbon build up.

pulling the heads will reveal if that is the issue.

check the pistons for any damage- persistent pinging can burn holes through the pistons

mike

 

Have you tried a cooler range plug? I believe the V-rod plug is the next lower heat range.

 

If it was not put on the dyno then chances are it's not getting the proper fuel charge.
It's needs more fuel for the work that's been done, more fuel = cooler temps in the cylinders which will greatly reduce pre-ignition (pinging).
Personaly I would pull the heads, you probably will not find a lot of carbon buildup if it has been running to lean, you may find pitted pistons and valves though from pre-ignition.
Just my thoughts, I've seen it before through 30yrs as a ASE Master Auto Tech.

 

I fully agree. There are dozens of tables in the ECM that must be set correctly. You can't just change the timing without looking at the total picture. After doing that much work on your bike it deserves a proper tune on a dyno by a good tuner in your area.

 

I suspect it is pinging under light load in the high cruise area around 2500 to 3000 rpms. I have seen this with the stage 4 set up with 10.5 and the same cam. We had to lower the timing to no higher than 36 degrees in this area and increase fuel about 5% here also. When you increase the load and get the ping it is in the 80 to 100% load area that needs changing. If in steady run condition it will be in the 40 to 50% area. Didn't have a negative effect on performance. He was running a 2 into 1 and it tends to lean it out from low end to midrange. True duals mostly need to be richer in midrange area. You can always put on thicker head gasket and lower the compression to closer to 10 to 1. I notice FM is using 10.25 now. Is that a Street tuner or the SEPST. If it is the Pro you can probably make it work. Street tuner not sure.

 

I'm going to take a stab at it and say I betcha the dealership retarded the timing too far. I started with -1 degree in 1 degree increments. I'm wagering the dealership went too healthy with the adjustments just to make the problem go away eliminating the ping but F---up the way it runs. Do you know what strategy they used or did they just say they retarded the timing? Perfect example of why I just got to do things myself so should it not be right, I know which direction to go next....hard to do that if someone else is doing the work.

 

Pre-ignition and pinging (detonation) are two different phenomenon. Pre-ignition always happens before the spark. Pinging always happens after the spark. Both have mostly different causes. A dyno tune session often can cure pinging if the cause is timing and/or fuel mixture related. Carbon buildup is less often the cause but possible in both pre-ignition and in pinging. An endoscopic inspection might reveal the buildup level.

 

It's been a long day so here are the definitions and symptoms of Pre-ignition and Detonation. As you stated they are 2 different Phenomenon.
I would be inclined to believe that the Op's bike is suffering from detonation and would most likely be cured with a dyno tune.
If it hasn't had any Stage 1, 2 or 3 downloads to the ECM it is in all probability running wicked lean.
Hopefully the Op gets some good info and can get the problem fixed, after all we are all just trying to help.

PRE-IGNITION
An engine can live with detonation occurring for considerable periods of time, relatively speaking. There are no engines that will live for any period of time when pre-ignition occurs. When people see broken ring lands they mistakenly blame it on pre-ignition and overlook the hammering from detonation that caused the problem. A hole in the middle of the piston, particularly a melted hole in the middle of a piston, is due to the extreme heat and pressure of pre-ignition.

Other signs of pre-ignition are melted spark plugs showing splattered, melted, fused looking porcelain. Many times a "pre-ignited plug" will melt away the ground electrode. What's left will look all spattered and fuzzy looking. The center electrode will be melted and gone and its porcelain will be spattered and melted. This is a typical sign of incipient pre-ignition.

DETONATION
Unburned end gas, under increasing pressure and heat (from the normal progressive burning process and hot combustion chamber metals) spontaneously combusts, ignited solely by the intense heat and pressure. The remaining fuel in the end gas simply lacks sufficient octane rating to withstand this combination of heat and pressure.

Detonation causes a very high, very sharp pressure spike in the combustion chamber but it is of a very short duration. If you look at a pressure trace of the combustion chamber process, you would see the normal burn as a normal pressure rise, then all of a sudden you would see a very sharp spike when the detonation occurred. That spike always occurs after the spark plug fires. The sharp spike in pressure creates a force in the combustion chamber. It causes the structure of the engine to ring, or resonate, much as if it were hit by a hammer. Resonance, which is characteristic of combustion detonation, occurs at about 6400 Hertz. So the pinging you hear is actually the structure of the engine reacting to the pressure spikes. This noise of detonation is commonly called spark knock. This noise changes only slightly between iron and aluminum. Incidentally, the knocking or pinging sound is not the result of "two flame fronts meeting" as is often stated. Although this clash does generate a spike the noise you sense comes from the vibration of the engine structure reacting to the pressure spike.

 

Great review of the differences, pswomack. Detonation is a constant worry to those of us with classic vehicles from he high performance era.

I'm wondering in the OP's description of his engine build what the cylinder pressure would be with that cam/piston combination.