Spark plug experts - diagnosis please!

Sergeant Pluck

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I did a 'plug chop' today... found a quiet road (easier said than done) got up to about 5000rpms and hit the kill switch. Here's the plugs - what do you reckon - would I be correct in thinking I'm running a little rich?
 

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Wouldn't of thought so Neil, although the left one does look a little Blacker than the right.... throttle bodies need balancing maybe?
 
Gilson said:
What does a plug 'chop' tell you, why do it and why is it different from just looking at them after normal use? (I really don't know...)
If you want to know what your plugs are burning like at 5,000RPM you need to go for a blast down a road holding the revs at 5,000 for a few moments then, hit the kill button and pull the clutch in straight away.

Once you've pulled over somewhere quiet, 'whip em out' and have a look ;)
 
Wouldn't of thought so Neil, although the left one does look a little Blacker than the right.... throttle bodies need balancing maybe?
Do you reckon they're lean then, or OK? I thought all the sooty black stuff everywhere meant things were a little rich - or am I mistaken?

One side has always been a bit blacker than t'other - even after the valves have been done and the TB's balanced... :nenau. Actually, these are about as 'equal' as I think I've seen them!!


What does a plug 'chop' tell you, why do it and why is it different from just looking at them after normal use? (I really don't know...)
Added to what BHT said - 5000rpm *seems* to be the spot where most people running non-standard exhausts report lean mixtures.... and I'm the nosy type!!
 
FWIW I'd say they may be a bit lean but if anything they look as if they are running a little bit hot.
I think I'd be tempted to try one grade colder and see what they look like - just MHO.

HTH
Andres
 
If those tips are as white as they look on my screen, it should mean they're running too hot.

A healthy colour should be more of a tan colour.
 
many modern engines run white or grey on the plugs. i go with the "any light colour deposits are fine"* school of thought myself. only my old bikes run tan.

i've found plug chops on my 1150 rather inconclusive. generally runs white/grey, unless you leave them in for a few thousand, then they lean more towards tan.

that sooty black is richness though. it's the sort of thing you get if the chokes on, on carburated machines :confused:


*deffo not shiny ally though :D
 
that sooty black is richness though.

Thats what I thought - thanks. I'd prefer richer rather than leaner. The plugs were coming out very 'clean' (although a nice tan colour) when I had the remus end can and beige plug in... These are how it is with just y-piece and no CCP. Might try dropping the TPS voltage a bit.

Thanks to all,
 
those plugs look like they've been revved before the engines reached it's proper full working temperature - the full 5 bars on the oil temp ?
 
I'd say you had the 'choke' on too long - pootled through town for about 5 miles , then sped up a bit to warm the bike up not enough -- then rode along at a steady throttle for a while. ( might be wrong ? )

What you need to do is have a fully warm engine, flat out or WOT for half a mile or so to clean the plugs, then uphill in 3rd/4th on WOT to 5k, then cut revs.

they'll still look the same though :D

look ok to me - left is a lot richer though when cold - throttle cable / quadrant worn ??
 
It may be an optical illusion, but the one on the left looks as if has done many more miles than the one on the right. Look at the centre electrode....
 
Right I'll do the bloody test again then!!

Motomartin, whats wot?

Littleredrooster - yeah it is the picture that looks odd - in real life the electrodes hadn't degraded.

I've replaced those pictured with some of these EON2 jobbies (thanks Straypuss) - I'll give them a few miles and then do another test... Although whenever I run just the standard can with the y-piece and no ccp, I get the worst fuel consumption of any of the combinations I've tried so i've always assumed it's running a bit richer in this trim.

Cheers all,
 


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