TOPIC:

I was hoping to gain some knowledgable insight on how to read these well used spark plugs. They did not come out of my KZ900, but I thought plug wear would be pretty universal in their interpretation. They have 18,000 miles on them. I finally replaced them yesterday. They're out of my Kaw Vulcan 1500. Considering they served me well for so long. Probably too long. During my last trip to New Mexico I felt the bike was running a little rich and my rear pipe began to discolor through the shields near the bend, like maybe a 2ndary ignition or hot spot. Would anyone care to enterpret the plug photo and share your analysis? Thanks.

They look like it's very lean, but that may be how the bikes are set to run now. I like to see the ceramic in a light to dark tan color.
Here is a pretty good web page of spark plug pictures

www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Post edited by: OKC_Kent, at: 2006/05/26 09:52

Skip, First, rich running isn't what discolors an exhaust pipe... lean running does. Next, it wasn't the stock exhaust that discolored, was it? On a Vulcan, you can't see the stock exhaust which is hidden under some "heat shields". Last, the plugs look just about perfect for a VN... VN plugs tend to soot just a tad if you putt around on the bike since their combustion chambers are way-small for a bike with that displacement. I would run some Sea-Foam in my gas and also spray some Sea Breeze (the aerosol form of Sea Foam) in my carbs now and again to avoid excess sooting. In colder weather, don't be afraid to use one heat range warmer spark plug. This helps the combustion chamber stay clean.

The VN family has a few quirks that confound some of the standard advice for a KZ as I noted above. Your plugs look great and don't worry so much. BTW: The Sea Foam product is a petroleum distillate and won't hurt your performance, the gas or internal components and it does work reasonably well to clean things. When you spray it in the carbs with the bike running, the smoke will scare you but that is normal. I know the VROC crowd is rowdy but they are a better source of Vulcan related info than you will find here. Don't be afraid to ask me questions regarding Vulcans either as I am VROC #2420 and have owned a bunch of them and have done a lot of mechanical work on Vulcans in the past.

Thanks all. Great insight George. Thanks for sharing. It's a year 2000 FI Classic. I put V&H Longshots on. I did not put a computer in along with the pipes as I was told the EFI would compensate, (which it seems like it did). The discoloration went through to the shield. So I wasn't sure if this was just a cumulative effect of changing the pipes and making a long trip or if a setting needed to be made since changing the pipes. It wasn't my intent to get off the forum domain and discuss vulcans here, so I'll take it off line. As usual I got great general info on this site. (thanks for the plug link OKC!)