plugs turning Black

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CM400ERider · Thu May 04, 2006 6:37 pm

I have been working on my KZ550 I changed the plugs. oil and filter and took it out for a test ride it seems to run fine but when I pulled the plugs they were black as the old ones I pulled out I thought the Carbs were out of sinc but after reading about sinc ing the carbs I am now thinking something else is wrong. could someone please tell me if they have had a simular problem and how they fixed it. thanks
Lorin

#2 Unread post by **Skier** » Thu May 04, 2006 7:02 pm

Match up your plugs to the images here and tell us which they match best. From that we can help you better.

CM400ERider · Thu May 04, 2006 8:16 pm

Skier wrote:Match up your plugs to the images here and tell us which they match best. From that we can help you better.

3 carbon fouled but It runs fine and has no aceleration problems.

NorthernPete · Fri May 05, 2006 11:30 am

mmm... #3...those loook like mine...

#5 Unread post by **Skier** » Fri May 05, 2006 11:44 am

Are you guys getting your bikes up to temp? Spark plugs are supposedly self-cleaning once they reach operating temp. If you only use your bike for short commutes, take the long way home and get on the throttle and get those cylinder temps up there.

flynrider · #6 Unread post by **flynrider** » Fri May 05, 2006 2:22 pm

That's what I was going to mention as well. Under low loading conditions like a short test ride around the neighborhood, you should expect the plugs to look a little bit black. Cylinder temperatures just don't get high enough to completely burn the fuel/air charge. A good hard ride at freeway speeds will clean them right up.

A couple of weeks ago I had a plug that was carbon fouled and missing at idle because I'd been doing a lot of low speed short trips. I didn't even bother pulling the plugs. I just hit the freeway for about 10 miles and the idle went right back to its usual rock-steady 1000 rpm.