Plug check please..

[red ghost]

Tell me, am I rich..



Am I lean...



Or somwhere in between..




Same plug, just different angles..

Help?

[Stampede]

How old is it / how many miles have you done with it?

[red ghost]

The plug is not too old, done maybe 100kms worth of jetting. So I guess it's never had the chance to really settle in..

[mnpes]

Ideally before you do the plug-chops the Squish Band wants setting up ~ Then with the correct grade plug and gap set for either points or electonic ignition

The tip looks fine but there is still oil around plug base ~ a nice chocalate colour is the aim

Was this removed from a plug-chop or just at random ? :bouncing:

[red ghost]

What I'm getting at is why is there two readings on the plug, rich one side lean the other?

Since I have fitted the mugello v4 this has always been the case

[wack 63]

I could be wrong but that looks like gear oil on the shell which could explain why you are having trouble setting the scoot up.One minute it is burning gear oil ,the next air.Personally I like to jet in with an old plug as it colours up sooner.Whip the mag housing off and if there is dark oil sat in the casing you will know.

[Muppet]

one side faces the piston the other faces the head when tightened up; differing temperatures allow the burn to ignite more one side of the plug than on the other; if you mark the rich side of the plug you will most likely find it's the side nearest the piston; that's when it's bolted up tight; i was told engines not being run up to full temperature yet; poor squish clearance and combustion volume could be something to do with what's causing the incomplete burn and ignition timing may play a part; and plug choice, thats what I was told when my SX was doing similar,

muppet

Wack 63 might just be right; or so I've since been told; it might be burning gearbox oil,

[Donnie]

quite a common phenomenon that on muggys to be honest, dunno if its the same with other alloy kits?

[ming]

My Rapido does the same thing. I think you will find that the richer side faces the top of the barrel, ie the intake side, and the leaner side faces the bottom, ie the exhaust, when the plug is fully seated. Which kinda makes sense. I just jet mine for a chocolate brown on the leaner side, to stay safe.

[starreem]

All mine do that. I attributed that to the off center spark-plug location in the head. One side is sitting just next to the squish band, and the other is facing the combustion chamber.