I know on two stroke engines such as snowmobiles jetskiis the plugs optimally should be a brown coffee color... What should they be on a harley? Check out the pics I attached.. Let me know if I'm running ok... Thanks!

 

A coffee or tan color is best on a Harley as well. It looks like it might e running a little bit rich.

 

How many miles are are them? What kind of riding do you do? You can get a basic idea of what your engine is doing by looking at the insulator but to truly read a plug is a more indepth procedure. But just at a glance I would say just a tad on the lean side. An ideal color would be similar to cardboard.

 

Your asking for trouble, bring on the armchair mechanics. Rich, Lean, Rich, Lean......
Good Luck!

 

Great reply.

 

Rich lean rich lean. Ahhhhh! Damnit!

Ok ok ok - the plugs are going on their 2nd, or 3rd season. I bought the bike 2 seasons ago. I ride farley hard. Mostly cruiseing. You say rich? You say lean. Christ. Lol. Loll. Uh new ones and take the old ones to the dealer. Lol.

 

no armchair here.. they look a tad lean. you always want to look at the insulator/porcelian part of the plug to read it, don't go by the body of the plug, it most likely will always be black to sooty since its the coolest part of the plug. that means you're getting enough fuel in the cylinders. if you have a magnifying glass, look down inside the plug and see if its tanish in color. if so, i would put them back in and keep on riding. as long as there isn't any deposits on the insulator or scale on the ground electrode or built up on the center electrode then you're good to go. sometimes changing the heat range of the plug for the type of riding you do can be all that you need to do to get the plug to burn a nice tan color the entire insulator surface. i would think with a air cooled engine the cylinder temps are going to be higher, therefore it will always show a little on the lean side unless you got it running so rich it burns your eyes standing behind it.

another easy way to tell if the motor is lean or rich, look up inside the exhaust pipes.. see if they're black = rich or tan/grey in color = normal.. if theres no color at all in the pipes, its lean.

 

http://lmgtfy.com/?q=motorcycle+spark+plug+color

couldnt resist...lmfao

'

 

I guess I walked into that one. Lol. It was just a question!!!! Lol. I've ran it for 5,000 miles or so the way it's been. So I guess it's good.

 

I would say they look OK. They aren't blistered around the electrode on the porcelin, but may be just a tad lean. I like mine to have just a little tan color, and my pipes to be dark grey. When my plugs looked like yours, my pipes were white.