Compression and leak down test

Top End (cylinders pushrods etc.)
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wayne-o
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Compression and leak down test

#1

Post by wayne-o »

Ok I did both test, this is what I got. compression front 75psi, rear 100psi. ok leak down test tha only air i can hear is out of the intake but very light can barley event hear it. So now what could be causing the front cylinder to smoke white and soak the inside of pipe in gas? Intake? head gasket? or any other ideas would be helpfull
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Re: Compression and leak down test

#2

Post by Panacea »

Did you try new plugs? Switching the leads? intake leak? I must have missed the first part of this thread, what carb are you using?
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Re: Compression and leak down test

#3

Post by hogboy52 »

The front cylinder is definitely low. White smoke is oil. Unburnt gas in the pipe is from the plug being oil-fouled and mis-firing. I would guess broken rings. If so the leakage would be into the crank-case, which might be hard to hear.
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Re: Compression and leak down test

#4

Post by Panacea »

You could try pulling the timing plug to listen for air.
wayne-o
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Re: Compression and leak down test

#5

Post by wayne-o »

Disregard the leak down results after thinking about it later I misused the tool so I will try again this afternoon. And white smoke is raw unburned fuel and my plugs are not fouled at all I have good fire I am starting to thing this is a exaust valve issue. I am running a s&s super e carb.
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Re: Compression and leak down test

#6

Post by steve_wood »

Wayne-o:

A couple of observations:

(1) Very strange that the plugs are not fouled at all. If there is an oil leak in the rings or valve guides, there typically is fouling on the plugs. Strange.....

(2) I always thought that white smoke = oil and black smoke = gas. The reason I believe this is that if you put a teaspoon of gas on a pie plate and light it, the smoke is black. Also, if the smoke is from burning gas, then why is there *unburnt* fuel in the pipes? Sounds like the gas is NOT burning. But I could be wrong....

Just sayin....
wayne-o
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Re: Compression and leak down test

#7

Post by wayne-o »

Ok i did the leak down test correctly this time, the air came from the timming plug so that would be rings right? But still the plug was never fouled up. I thought it was unburnt fuel because of a exaust valve problem. I gues I shouldn't argue I'm just learning. so what are the next steps I take?
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