Left plug dirty

[cWj]

While I was suffering my charging system episode, I decided to change to NGK Iridium plugs. When I took the standard NGKs out, I noticed Lefty was wet and sooty, righty looked ok.

I thought it might have to do with the low spark situation (fuel not being burned), so I tossed the Super Plugs from Outer Space in.

I switched the regular plugs back in last night.

This what the Iridium plugs look like after about 500 miles.




Dirty again. Left side again.

Hm.

Champion site sort supports my assumption.

"Other causes include weak ignition system voltage or an inoperative pre-heating system (carburetor intake air) or poor cylinder compression."

But I'm wondering if it isn't a sticky valve....

Has anybody else ever seen uneven fouling due to poor voltage? The Iridiums were definitely in the bike during some of the low voltage problems.

Guess I'll get some carb cleaner and see if I can salvage this 8 buck plug.

[robfriedenberger]

Try swapping your coil packs.

If there isn't a change in the plug conditions than you know you have a an issue with the carb/valves/cylinder/wiring 

--If this is the case I would suspect a carb issue first, and also check the compression on the cylinders.

If there is a change than you know you have a failing coil.

--You should be able to check your coils a few ways,.

--A. If the supected bad coil is excessively hot (its bad)
--B. Compare resistance on the coils, I don't know the specs for these coils but usually they are 4 -8 ohms for bikes

[TR]

Just for the record, in case someone dig in for an answer, a bad pickup signal coil might make ignition fail as it gets hot, it happened to my GS some years back, and I ultimately found a broken magnet in one of the pickups of the signal generator. It's worth to take a look at those little bast***s.

[herennow]

Personally, I prefer the colour on the left. The porcelain on the right looks very white (lean) to me as well as the lack of discoloration on the electrode. There is a guide That gives additional information on the upper electrode colour which I would try to dig out.
if you can, a picture from the top looking down onto the porcelain can also be helpful.

Might be lean due to air leak.

[Kito]

YEP... instead of checking the brownish side.. I would start looking for clogging on the whitish side carb.

Too white is not a healthy sign AFAIK.

cheers

[herennow]

here are the pics I was talking about.

2nd and 4th are most relevant to our bikes. Reading plugs is now very different to when Gas/Petrol still had lead in it. Those old tables of pictures one finds are still helpful but it's much less easy to read plugs these days.

Today the main clues come from the plug base ring, and then the ceramic colour.

[Kito]

Nice post!

[Kilted1]

With 500 miles on those plugs, I think they both look pretty good.  Maybe the left carb is about 1/8 turn richer than the other, or the float level is different by 1/4mm, or maybe they need syncing. 

So long as things seem to be running right, I'd sleep just fine with those plugs in my bike.