I recently got this bike, so I'm not sure about the prior service history. The SE 103 motor has 18,000 miles on it. I'm in the process of going over everything any replacing all of the necessary parts. I pulled the plugs, which by the look of them could be the originals from 2006. The threads were covered in carbon, but the tip was white. The plug gap was pretty wide, although I didn't measure it.



Based on the pics/ description, does the white on the tip mean its running lean? I realize the only way to be sure on the air/fuel mixture is to get a dyno with a wideband o2 reading, I'm just looking for an idea. BTW the motor runs great, both before and after the plug change, however there is a decent amount of decel pop.

Thanks
Erik

 

Those are some old/weather-beaten plugs! I hope the rest of the bike isn't that rusted up.

White is indicative of being too lean. Tan to grey is indicative of a proper A/F mixture. Only way to definitively know is to put in on a dyno.

 

 

Yeah, tell me about it. The rest of the bike appears to be in good shape, however there are some small hints of rust showing up in places like the recessed torque bolt heads. The bike was a one-owner bike from Florida and apparently the previous owner actually rode quite a bit, judging from the miles.

I'll see what the local shop charges for a simple dyno with o2 reading. If its in the area of $100 I might just wait till I get a tuner installed before I hit the rollers.

Elfnyc-
Thanks for the picture.

 

If your bike is fuel injected I believe you can NOT READ PLUGS BY JUST REMOVING THEM. You have to ride it a bit and shut off the bike while the throttle is applied, stop the bike of course after and then remove the plug immediately to get a reading.

 

Judging from the chart above, looks like they've got some ash from fuel additives. I've seen this on a car I owned twenty years ago... was running premium fuel (94 octane) and the plugs weren't gapped properly. Solution was gapping the plugs and changing brands of fuel every fillup. The plugs should be clean with a slightly tan insulator, with minimal carbon deposits. You can diagnose an AFR problem with a simple 'plug chop' procedure at different throttle positions. It will at least give you a ballpark idea for an EFI motor. Tuning it is a whole 'nother can of worms.

 

It is fuel injected, but what does that have to do with it? I don't doubt you, just never heard that before. Keep in mind I'm only looking for a general idea of the operating condition of the motor. From what I remember, a whiteish tip generally means a hot (or lean) condition, but I was looking for some confirmation on that.

 

JohnK- Good advise. I did fill with premium (several tanks now) and replaced the plugs today. Never heard of the plug chop, I'll have to google that one.

 

Those are pretty beat up weathered plugs! Katrina Bike? Seriously dude.

 

heritageblue has a basic description of a plug chop. You ride the bike at a steady rpm for a bit, pull the clutch and hit the kill switch. Coast to a stop and pull the plugs on the spot to get the most accurate reading. This needs to be done at three different throttle positions: off-idle, mid throttle, and WFO to get an overall picture of your AFR. Also needs to be done with fairly fresh plugs. This is your guide to tuning a carburetor, but it can give you an idea if your EFI is working properly or you need to invest in a tuner. Plenty info on the interwebs on spark plug chop.