Spark plug condition

[moto]

I have opened up the airbox, fitted a foam filter, put big bore headers and a less restrictive silencer on.
The bike feels like it is running great, responsive throttle, no lurching or backfiring.

There is some popping when I go downhill with zero throttle (is there a name for that?) , I don't know whether this is normal but it did it with the original exhaust too.

I made sure to put fire gum on the joints.

Anyway I want to make sure it's not running lean.
I took the spark plug out and it does not look like any of the pictures I found in this old thread.
The condition of the insulator (white) and electrode (no deposit) look fine.

https://www.bikechatforums.com/viewtopic.php?t=197961

The side arch bit is a dry greyish colour, the first thread of the plug has a dry black deposit. Not sure if the poor quality pics show that up.

[0l0dom0l0]

if a bike is running rich or lean, its normally very clear. rich, the plugs are black, lean, the plugs are white. if after a week or so your plug is white, (or a very light grey), you might need to richen up slightly.

from the picture you posted, it all looks fine. if your worried, change the plug to a new one and after a couple of days check it. if it looks simular to when you put it in....everythings fine.

the popping is misfiring btw, its where the fuel isnt ignited in the cylinder, instead its pushed though the exhaust and ignited there. nothing to worry about!

[moto]

I was never sure if it was normal for that popping with zero throttle going downhill so thanks for clearing that up.

Where exactly should I be looking for the black or white deposits, on the electrode?
The arched piece of metal is a mid grey colour.
I could always richen it up a tiny bit by undoing the air/fuel screw 1/4 turn.

It is an Iridium plug that I put in about 2000 miles ago.

[0l0dom0l0]

the popping is very common, it happens especially when the throttle is shut, and you are moving (ie. engine braking). the cylinder is moving a 4krpm say, but its only getting enough fuel to be doing 1k rpm, so there isnt enough to ignite in the cylinders. its very common.

wouldnt need anywhere near a 1/4. 1/8 max if any adjustment needed doing. sounds fine by what you have described. sounds like its running pretty good indeed.

hope this helps!

[moto]

Yes very helpful thank-you.

[temeluchus]

If you get popping on the overrun, but the plugs and mixture looks good check the condition and fit of your exhaust for leaks.
____________________
Some shite cruiser. Now with guns and FREEDOM!

[el_oso]

can't really tell from that picture. looks a little black but may just be crappy picture.
black means slightly rich mixture or too cold of a plug.
what plug do you have in there at the moment? also what bike?
popping on over run is failry common. not usually anything to worry about unless it is excessive. it is caused by fuel being ignited in the exhaust. when you twist off the throttle fuel is still being sucked through (due to there needing to be fuel for idling) and not being ignited by the spark plug as the timing starts to go off because of the slowing motor.
excessive popping can be caused by an air leak somewhere in the system
(this sounds a bit like a load of waffle but i know what i mean)
____________________
Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[MaybeGuy]

is it just me or does the electrodey bit look really worn, and the plug gap is massive?
____________________
Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[temeluchus]

[moto]

It is an XT600E and the recommended plug is
DPR8EA-9 or DPR9EA-9 (NGK)
The plug I took out was a DPR7EA-9

Which number denotes a hot or cold plug?

Anyway I now have a DPR8EIX-9 NGK Iridium.

The recommended gap is 0.8-0.9mm.

It came already set at 0.9mm I just checked it and it's still the same gap.

[temeluchus]

the higher the number the colder.

Heat range 8 does sound about right for the bike.

Could you get a better picture of the tip?
____________________
Some shite cruiser. Now with guns and FREEDOM!

[sniff6]

Dont know if this helps:

https://www.hayabusa.org/forum/attachments/maintenance-do-yourself/116966d1223649221-spark-plug-condition-reference-pics-scan10001_edited.jpg

Reminds me of the picture from the haynes manuals

[moto]

temeluchus,sorry for the poor quality picture, the cam is not very good, I took loads of pics in different light and positions and those were the best.

The plug is back in now.

Are we talking about the number right at the end or after the 3 letters that denotes the temperature?

Thanks for the pics sniff, I guess it is closest to the top left picture.
Greyish deposit.

[.]

DPR7E means D thread size, P for projected tip, R for resistor, 7 for the heat range, The E after the number denotes the length of the thread.
The rest refers to the electrode size and/or material, and as shown on yours it also includes a production line gap size

if your pictures are of a 7 heat range plug, then changing to an 8 will result in a slightly darker centre electrode colour, assuming nothing else is changed.

[steven_191]

how do you work out what heat range you need for the plug?

[moto]