OIL FOULING PLUGS

Hey guys
plugs 1,3,4 are black with oil on them. they are brand new plugs, after running for 10 mins they went black with oil on them.
plug 2 still looks brand new.
Would my rings be worn?valves worn out?
this is my first bike, any help would be a help.
i am willing to pull the engine out and try a rebuild.
cheers, john

 

Don't just tear into it, you need to diagnose first.

Do a compression test. If the compression numbers are good, you can move rings down the list.

The most likely culprit is valve stem seals, which would only mean pulling the head. You can leave the motor in the frame for that.

So, start with a compression test. If you get decent numbers, pull the exhaust system and carbs off and have a look at the backside of the valves through the intake and exhaust ports.

 

Is it a dry, dusty black, like charcoal, or a wet black??

If it's dry, you are running rich.

 

It's a wet black. Compression is all good. If I can get away without taking the engine out, that would be sweet.

 

They also look alittle charcoaly. With a bit of oil on them.

 

Since leaky exhaust seals would blow out the exhaust and not get back into the cylinder, we're only talking 4 intake seals -

Has noone figured out how to pull the spring and keepers without pulling the head??
This is done on cars all the time. (compressed air or the rope trick)

 

Exhaust seals can contribute to oil in the cylinders too, trust me on that...

The problem with the compressed air or "rope trick" on these motors is the dual-coil valve springs and difficult to access valve pockets due to their depth and position relative to everything else around them. Using compressed air, one minor slip-up and you're pulling the head anyway; and the "rope trick" won't hold the valves fully closed tight enough to accomplish the task.

It ain't a Detroit V-8.

If the compression's good, the prognosis is looking more like valve stem seals. Pull the carbs and pipes and confirm (you'll have to pull them to pop the head anyway.)

You CAN pull the head with the motor in the frame.

 

Are you sure it is oil fouled, and not just running really rich? An engine running way rich, will build black carbon quickly before fouling and then get wet. When the fuel mixes with the carbon it make the plugs look shiny black/wet. Before you pull anything apart, there is another thing to try. Take the old plugs out and put them aside to "air out". If the wet black stuff dries out, then it is fuel fouling. If it doesn't dry out and leave the chalky black residue, it is oil fouled.

Put new plugs in, start engine and watch exhaust. Blue smoke = burning oil. Black smoke = burning too much fuel.

 

I have had the carbs out and given a thorough clean, oil is new.
If the valve stem seals are worn , what am I looking for? Will it be clear if they are worn?
The smoke looked Bluey grey, definitely not black.
Ill be pulling the carbs/exhaust off tomorrow. I'll take photos.

Thanks for all your help guys!

 

I've also had problems with my bike.... I took the old plugs out (not sure the last time they were replaced) and they were black.... replaced with new ones...

What should I be keeping an eye on here?