Oil Coming Out At Spark Plug

Karl Snarl

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Sep 20, 2019
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3,173
I thought you said you had oil in the magneto side? Maybe that was @Aikaru, swore it was you. My bad, but naw unless the plug is hanging out the oil seep won't really take much compression. I'm thinking you have a gasket leak bro. It's all the classic signs. I even went through it when tuning 'ol red my nitro bike. Turns out for me it was timing, but you are a gasket leak. Runs alright when cold, little dinkin, but alright. Then a few minutes later when it starts to get warm it goes haywire and no two plug readings are the same. You richen it up and it gets worse, you lean it and it won't run. It's a bad gasket somewhere. Only thing it can be besides oh a cracked jug/case/head/etc.

Or did you say something about it dripping oil from the underside? I know I was helping some one that had a bad crank seal. Frogslayer was helping them too, gave some pointers on how to tap the crank seal in.
 

yuckfoo

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Nov 21, 2020
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703
I thought you said you had oil in the magneto side? Maybe that was @Aikaru, swore it was you. My bad, but naw unless the plug is hanging out the oil seep won't really take much compression. I'm thinking you have a gasket leak bro. It's all the classic signs. I even went through it when tuning 'ol red my nitro bike. Turns out for me it was timing, but you are a gasket leak. Runs alright when cold, little dinkin, but alright. Then a few minutes later when it starts to get warm it goes haywire and no two plug readings are the same. You richen it up and it gets worse, you lean it and it won't run. It's a bad gasket somewhere. Only thing it can be besides oh a cracked jug/case/head/etc.

Or did you say something about it dripping oil from the underside? I know I was helping some one that had a bad crank seal. Frogslayer was helping them too, gave some pointers on how to tap the crank seal in.
No I pointed out a drop of oil under the magneto case. But then realized I had oil coming from the plug.
 

Karl Snarl

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Sep 20, 2019
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3,173
What a about a compression gauge? Wouldn't that show if I had a leak for any reason?
No, it will only show compression. You are thinking of pressure testing. You pump the engine up to 4-5 psi and then see how long it takes to leak it.


I actually do it backwards, I rigged up my brake bleeder to pull a vacuum in mine. lol. Then I can watch the gauge. Its same set up, with rubber plugs, but I just use my brake bleeder to watch it. I don't have a cheapo brake bleeder, it's pretty fancy. An I could use my ac pump to pull a vacuum, but tht puppy will pull till 5 atmospheres below before it has no more get go. I'd prob suck the gaskets inside with tht much, lol
 

DieselTech

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Sep 18, 2021
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2,074
Lol never thought about using my ac vacuum pump to test these 2 strokes, that's a good idea @Karl Snarl way better than pressure testing cause you run the chance of popping out a crank seal with pressure.
 

Karl Snarl

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Sep 20, 2019
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3,173
Remember, that won't be "pag" oil that you will be recovering there, nor is it R-12 or R-134A either...lol...lol.
Thats why you do a collection cup before if you are worried. I used to use a ball jar as a collection cup for doing brake bleeds. With the ac pump as the vacuum. Really though it only runs a few seconds so doesn't pick up much oil if any. Any gas left will vaporize quick though. Then all ya have to do os change the oil. Its not that badly priced.
Lol never thought about using my ac vacuum pump to test these 2 strokes, that's a good idea @Karl Snarl way better than pressure testing cause you run the chance of popping out a crank seal with pressure.
I did it because I don't have a pressure gauge but I have a multiple vacuum gauges.
 
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