oil on spark plug threads

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magna_dude74

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Hello All,
So I was bored in the garage and started looking at my spark plugs, and O noticed that the front two plugs have oil on the treads.:confused2: The plugs I am running are the NGK Iridium IX, number DPR8EIX-9. This plug was recomended from my local auto parts store, I know I should have done more research before putting them in. Maybe the oil ring doesn't fit like other manufactures. What does everyone else run, please keep in mind that I am running totaly stock set-up.
Thanks for your help
 
I found the same thing during my last oil change. Not sure what to think other than maybe time to chase the threads to clean....or slight valve guide leak.
 
Never ever listen to the guy in the auto parts store - they actually know absolutely nothing about your vehicle - they're just trying to upsell you stuff.

The more money you spend, the happier they are. They are trained to do this as it's their job!

Stick to the stock plugs, there's nothing wrong with them.
 
Hijacked the old thread, if You don't mind.

A while ago I changed the plugs for a first time and I also discovered oil on the threads of all four plugs.

The plugs were completely black which tells that it runs rich, but is the oil something to be worried about?

I changed the oils at the same time and the oil that was drained was much dirtier than what was on spark plug threads.
 
There was no oil coming from the gaskets either. Maybe it's just that PO has oiled the threads so the plugs would be easier to change. I live in hope.

I don't have the possibility to ride my bike until april, but I'm going to check those plugs after some riding.

Those F/A screws were out about 4-5 rounds each, so the mixture was rich indeed. There was also some smoke when idling. Adjusted the 2.5 rounds out and going to continue from there.
 
I know compression will reveal valves or rings, but is there anything that would knock valves out of adjustment or screw up rings enough to give 20mpg fueling? 98%+ positive it's not my carbs.

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Last edited:
I know compression will reveal valves or rings, but is there anything that would knock valves out of adjustment or screw up rings enough to give 20mpg fueling? 98%+ positive it's not my carbs.

Sent from my Galaxy Nexus using Tapatalk 2


did you check your valve clearances? i know mike had a similar issue at once (95spngfld) where he had a rich issue get build up on the valves, and the clearnce was shot. so he set them right and that caused the engine to run right but then he had to set the valves proper with the carbon burnt off.
 
Haven't done valves yet. Waiting on decent leakdown tester to show up so I can check it out. When I had the carbs off there was a lot of carbon on the intake valves. PO started it once a month and let it idle up to the dot (so he said second hand) and shut it down until he destroyed the carbs by pumping in gas jelly...

Sent from my Galaxy Nexus using Tapatalk 2
 
Maybe the oil is coming down from the top....how are your valve cover gaskets?

Quite likely. Even a tiny little almost invisible leak will leave oil in the hole so when you screw the plug out, it gets deposited on the threads.

The other likely scenario is it's not just oil! Stuff from the comustion chanber can get on the threads coz the gasket is at the top. If a carby is over fuelling, petrol can get forced up in there, but petrol evaporates leaving behing dye and other shit. Also, when rich the oil on the rings gets washed off (ring wash Lol :biglaugh:), and the extra oil vapour in the cylinder will mix with the fuel vapour and get up onto the threads as well.
Also, it sounds likely as you have shitty gas milage.

Sometimes if theres a bit of oil around I whack a bit on the threads for good measure, so I guess the PO might have done that too.
 
PO started it once a month and let it idle up to the dot (so he said second hand) and shut it down until he destroyed the carbs by pumping in gas jelly...

That was NOT a good idea. Unless you intend to ride the bike and get it up to operating temperature then best to leave it tucked up in bed.

It could be that process was the cause of the issue.

Before getting too worried run it with new set of plugs and see what they are like when you get back.
Also make sure that the oil is filled to the maximum mark and over the next few hundred miles see how much it is using.
Measure how much you need to put in so you can work out the exact consumption.

If the consumption is within reasonable bounds then just ride and enjoy.
 
Tell me about it. Bought on consignment at a shop full of liars. I replaced plugs in the carb fixing process, so they're new, but I'll get some more. Would gap checking fix spark issues? I've never fiddled with that.

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I've had major problems with this bike, but I'm stubborn and will stick with it until it's all fixed.
 
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