I have a 2006 Heritage Classic, fuel injected. I removed both spark plugs, and they were mostly black and sooty. They are HD 6R12. Is this a sign that the engine is running rich. Is there a spark plug chart that shows the range of plugs. Should I run a cooler or hotter plug? Thanks

 

is the bike stock? doesnt sound like it...
sounds like the pipes and sucker were changed and the fuel controller is set too rich

 

Totally stock, except for some chrome items

 

it has baffles and Cat

 

cg, this bike stock, or does it have pc, heavy breather, pipes? Help us out a little!

 

did you buy it new or second hand?

If bought second hand, the previous owner might have had it tuned and then stripped off the after market exhaust and air filter and replaced with stock items but left the tune on the ECM, before selling it on.

(just guessing here, but usually a stock bike runs lean, not rich)

 

Most stock Harley's run on the lean side. Let me ask my friend, hope he's not in bed!

 

The pipes tell more than plugs with modern gas. Many say that you can no longer read plugs, other than to know that they are firing.

As someone said, they are set very lean due to EPA. The question about whether you bought it used or not is probably what you should answer next. After that, does it run well in your opinion? How many miles are on the bike? What gas mileage are you getting? Is there a piggy back fuel manager or a non-stock ECM under the seat or behind the battery? After that, have someone check the spark strength.

 

The HD 6R12 is the "Harley Standard" for 88" and 96" motors. Other than just pulling the plugs for ***** and giggles, was it doing anything to prompt you to check 'em?

Linking a Harley Spark Plug Cross Reference Chart for reference.

 

Good point