[size=13px]Hello everyone, I removed the 2 spark plugs on my Dyna 2005 to inspect them and they are very different, the one from the front cylinder has more carbon deposit on it, the other one looks more normal. Does it mean that the front cylinder has some kind of problem? If so, how can i fix it?[/size]



The one on the left is from the front cylinder

 

I`ll give this one a shot seeing no one else has. They should both be tan. Front cylinder looks okay, rear looks lean. Flame away experts.

 

If you have an injected 05 there are no O2 sensors to adjust the fuel. The ECM has been programmed at the factory to respond to different and varied engine requirements The 05's were/are leaned out by the factory. It's quite possible the front injector isn't closing completely and dribbling extra fuel in the cylinder. Try running some SeaFoam or Techron injector cleaner at recommended mixture for atank of fuel and see that helps with the rich condition on the front plug. The rear cylinder will be a bit hotter due to it's position in the frame.

 

Mine is carbureted. To fix the problem should i rejet it?

 

If it runs and idles OK, would not worry about it. Won't hurt it,

 

How many miles on the bike and on those plugs.. They look very new.. A little more history on the bike would help.. How long have you owned it? Has any other mods been done to the motor?

 

Any change affects both cylinders.

 

Your problem is using the NGK plugs!!

 

I owned the bike for a year now and it has 51573 miles on it. I bought it stock but i changed the air intake for an S&S and put on Vance and Hines slip-ons, and rejetted the carb.

No mods have been made on the engine since i got it but i couldn't really tell what's been done in the past. The chain tensioners are in good shape.

I changed the plugs recently and when i removed the old ones, i noticed that the front cylinder plug was more dirty than the rear one and there was some oil on the threads. So i figured that maybe it could be problematic. After i put the new ones i did some test drive with it and then removed them to inspect and i took the picture that you saw above.

Maybe its nothing to worry about but if it indicates an engine problem, i'd really like to fix it before it gets worse.

Thanx for your help!

 

To the OP, you mention oil on the threads. The 05's had a valve guide seal issue, some motors were built with the compromised seal. I had both heads fixed on HD's dime way back when. If the front guide seal is bad the black carbon look could oil leaking down into the cylinder. I've got an 02 carbed Dyna with basically the same mods you have. I removed the plug covering the idle mix and turned the needle out about 2 1/2 turns, raised the main needle with two #4 brass washers to get rid of a off idle "carb fart". My jets are still stock. The engine is now a 95" with HD 203 cams and runs good. The displacement gave me a few more ponies and the cams gave me some more low end torque for two up riding. the cams also give the engine a funny lope and idle sound. . FYI the updated seals p/n 18094-02A.