Topic: 2 plugs black on one side ...

[grumpy]

My 1 and 3 plugs are carbon black on one side of the insulator and white on the other.
The interweb tells me that the black side was likely facing the intake and/or toward the cylinder wall (ie facing away from the hottest part of the flame).

So does this just mean those 2 are a bit rich or is there something else going on?

[Jerry Rxman Griffin aka MuthaF'er]

Any time I see either 1 & 3 or 2 & 4 mentioned like this in the same breath I always suspect the ignition system. Forget the carbs (for now)! Condenser, point, coil for the suspect pair since each of these items affect BOTh plugs equally.

You could swap condensers first and see if it corrects. If not then swap coils and see if it corrects. Can't swap points but check the suspect point for gap, pitting, burning, etc. Check timing on BOTH sets. Guess you COULD have BOTH plug wires bad but unlikely. Same for plug caps.
What am I missing guys?   

SO BUSTED!!! 

[grumpy]

Aren't coils / condensers / points paired 1-4 and 2-3 ?

[Jerry Rxman Griffin aka MuthaF'er]

DOH, stupid moment on my part  But hey, it sounds good.

Soooo, with this in mind, are all your carbs jetted the same? Could have different jets. Are they clean and set up properly? Did you swap the plug wires around ie 1 with 4 and 2 with 3?

[grumpy]

HA! 

I did an uber, super meticulous carb rebuild last year when I put in a new motor. haven't been into the carbs since & this just started so jets & floats shouldn't be the issue.
2&3 plug wires won't reach to 1 or 4 so that's out.
Maybe I got some debris in the emulsion tube airways? weird that it would happen to two at once, though...


could valve lash, an exhaust leak, or something like that do it?

I just checked the air screws & they were all at 1 turn out...

gah. I'll just give it a WOT blast through all 5 & clean everything out.

[Jerry Rxman Griffin aka MuthaF'er]

No, swap 1 with 4 and 2 with 3. Should be equal lengths. See if the problem moves around then. It would be good to have clean plugs or maybe that would be enough to clean them off.

If valves are not correct the cylinders could show rich/lean. Too much/not enough air vs fuel. I wouldn't worry about an exhaust leak.

[grumpy]

No, swap 1 with 4 and 2 with 3.

Ah, OK. I'll give it a shot.

I'll recheck the valves, too.

Then I'll do the WOT ripper - cuz I like doing that.

[dave500]

got some photos?its probably nothing to worry about,you might not be riding it hard enough?

[grumpy]

got some photos?its probably nothing to worry about,you might not be riding it hard enough?

sorry mate, just cleaned them off & buttoned it all back up.
but picture this: if you're holding a plug upright, looking at it from the "side" (if cylinders had a side), then the left half if the insulator would be carboned & the right would be clean. 

well, it spends most of it's time on the highway running at 70mph & 5,000 revs with an occasional shot up to redline to get past texting #$%*heads...

[dave500]

they wont be low speed fouled then,if the bikes running fine itll most likely be ok.

[bwaller]

The darkened side would be in the path of the inlet charge which has a cooling effect. The opposite (white) side is out of the charge path & therefore hotter keeping the insulator clean. They can darken quickly.....the last half block on the way home? Who knows. You should always change plugs before a chop, but I bet if you tried one with those plugs, they'd be white all the way around.

[grumpy]

They can darken quickly.....the last half block on the way home? Who knows.

I'll buy that.

Screw it, enough fiddling. Unless it gets way worse I'm gonna ignore. it.