Reading plugs

[gwcrim]

Finally got my green monster running pretty well so it's time to focus on tuning.  At WFO and higher revs, I hear pinging.  Attached are shots of the plugs.  Not a surgical plug chop.  They've got 20 miles on them.  They look sort of OK but look at the ceramic. 

Thoughts?

[gwcrim]

The other one.

[Jspooner]

Plugs look a bit lean. Double check your timing. What are your mods and what is your current jetting?

[pdxjim]

Way lean and if you hear pinging, something ain't right.

The real place you want to be looking is at the base of the insulator, not out at the electrode.

[Old Brit]

Way lean and if you hear pinging, something ain't right.

The real place you want to be looking is at the base of the insulator, not out at the electrode.

I've always used an Otoscope to look at plugs at the track which has had even more general use since becoming rather more "mature" 

[gwcrim]

Mods: 

Spec II Stage 2 porting, coils, and F1 pipes
Banshee pistons and intake boots
YZ125 reeds
Y boot with Uni filter

Jetting:

Stock carbs
260 mains
32.5 pilot
Stock needle with the clip 4 notches down

I did do a leak down and it was good.

I took great care in setting up the timing.  Don't recall what that spec is at the moment but I think I did 1.8.

[Jessup]

An overly-rich engine sputters at WOT.

Spark plug color is irrelevant.

[m in sc]

GO TO A 170 main, see if the pinging reduces. if it gets better, fuel. if not, timing.  (typo... meant 270. lol)

[Old Brit]

Spark plug color is irrelevant.

Yeah right 

[teazer]

side and center electrodes are a good place to look for overheating and the base of the insulator is where you look for mixture.  Both side electrodes look burned clean and the upper center electrode also shows that it's been running too hot.

The question then is why.  Could be too much advance, or plugs too hot (try B9) or lean mixture.

Try 280 main jets and if the start to take color, check out the insulator and see what that looks like.  Rinse and repeat.  If you get to say 320 and the electrodes are still burned clean but there's a black mixture ring, then the plugs are too hot or ignition timing is too advanced.

[Czakky]

 

[gwcrim]

I'm using B9 plugs already.  Just 270 jets to try.  Hope to get a nice day to do a little more tuning.

[gwcrim]

The 270 jets seem to have eliminated 90% of the pinging.  I'll keep moving upward.  Based on that jetting spreadsheet, the bike needs more fuel than everyone else uses.  Wonder why?

[Barrie]

Worn crank seal maybe, air leak ,or it could just be a greedy bastard.

[gwcrim]

Crank seals are new.  I pressure tested it on assembly and it held air.  I'll just keep throwing fuel at it as long as that makes improvements.