compression testing two strokes

[marinemech]

a compression gauge doesn't always give a true reading of the cylinders conditition a better way to tell if you have a cylinder down is to rotate the flywheel with a wrench and feel the compression you will be able to "feel" if you have a low cylinder i almost never use a gauge to check compression<br />also while rotating flywheel you should be able to here the reeds work

 

[walleyehed]

Re: compression testing two strokes

The "best" method is a leak-down test, and in most cases, you can tell where the low cylinder is losing the air.<br />We're not looking for just a "dead" cylinder...we're looking for any differences between the particular # of cylinders.

 

[Hooty]

Re: compression testing two strokes

Originally posted by marinemech:<br /> a compression gauge doesn't always give a true reading of the cylinders conditition a better way to tell if you have a cylinder down is to rotate the flywheel with a wrench and feel the compression you will be able to "feel" if you have a low cylinder i almost never use a gauge to check compression<br />also while rotating flywheel you should be able to here the reeds work

 

[Hooty]

Re: compression testing two strokes

Interesting.<br /><br />c/6<br />Hooty

 

[JB]

Re: compression testing two strokes

Hi, MM.<br /><br />You are going to rotate the flywheel with a wrench and determine if the cylinders are within 10%-15% of each other, as specified by the manufacturer?<br /><br />You might find a completely blown cylinder that way, but you will never in ten thousand years verify the 10% spread.<br /><br />Your recommendation to "throw the guage away, it is useless on a 2 stroke" is irresponsible nonsense.

 

[stsmith]

Re: compression testing two strokes

Thank You JB<br />A compression test is one of the ways to check a cylinder on any combustion engine; however the other methods are helpful as well. But no one method is complete by itself. All three should be used! <br /><br />Smitty

 

[G DANE]

Re: compression testing two strokes

I have to second JB here. I have often pulled cord slowly when starting working on a motor that wouldnt start, and true it is, you can feel if all cylinders have compression. But when using gauge afterwards, I often discovered they were not equal at all.

 

[reeldutch]

Re: compression testing two strokes

if i buy a used engine the first thing i would do is hook up a compression tester.<br />if it is a v4 or smaller and the comp of one of the cylinders is below 100 psi and or not within the 15 lbs margin i will make a offer as a parts or rebuilder engine.<br />may be you should trow out a spark tester also because marinetech might recomend to feel that too.<br />hahaha.(just kidding)

 

[jim dozier]

Re: compression testing two strokes

The first thing I would do if my marine mechanic said he can evaluate my engines compression by feel would be to find another mechanic. Instinct is good for pointing you in the right direction. Quantifiable data is what tells you when to stop looking. Welcome to the new millenium.