Spark plug reading
 

I also posted this in the KLX thread over at advrider, but I figured more people might see it here.

What do you think of my spark plug?
2009 (EFI) KLX running a 292cc kit.

Rich, lean, good bad?

Attachment 35723

rich imo

Can you describe exactly how you obtained your plug reading...by that I mean what was going on with the engine prior to pulling the plug?

You have to start with a new plug and run it in the rpm range you're looking to examine the jetting in. Not much you can do with EFI anyway is there?

Here's a chart to help you rate your plug.

https://www.kawasakiforums.com/forum...ur-plug-39758/

Yeah what he said, if you want to know top end jetting put in a new plug, warm up the engine, then go full throttle in 6th gear, shut it down(hit the kill switch don't let come back to idle), then read the plug.

Trying to use plug coloring on modern engines running unleaded fuel really only gives you indications if it at the extremes of rich/lean. It's damn near impossible to fine tune without having a wideband O2 sensor setup to give you real time A/F readings. When I was running my 8.90 sec. Mustang I ended up using a computer system that would data log during runs so I could adjust fuel trim on the engine and nitrous system. The fuel I was using was leaded race gas so the plugs would color during passes but it still required a trained eye to give you accurate readings.

Hmm ok, so its not as simple as I thought to read the spark plug :P

To answer the questions:

Reading was done after a 50km spirited ride off small roads in the countryside. I ran it hard throughout the entire rev range. Plug has been on the bike for about 5000 kilometers. (Iridium spark plug)

Its an EFI bike yes, but I have a EJK fuel controller on it, which means I can adjust it. I've put on a 292cc big bore kit and I need the controller to feed it.

Yeah, you won't get any kind of usable data from your plug under those conditions. And unfortunately, as stated, today's fuel and highly efficient combustion process probably won't give you anything of any value in detecting proper fuel/air ratio. You just about have to go by engine response and driveability. Even after installing an aftermarket 36mm pumper carb on my KLX, I only pull the plug when it needs replacing...which for an iridium is a very long time.

You could record your current settings now and play with the jetting (fuel controller?). Make it leaner in the mid range and see the response, etc etc. Only do low,mid,upper once at a time though