lubing 2 Stroke before Compression Test

[aMeyers11]

Hi everyone, I just have a couple basic questions. So before messing with my ignition system I decided to do a compression test. I'm not sure how long the motor has been sitting. I can turn the flywheel by hand but I'm worried the starter could damage rings or cylinder walls with little lubrication. My question is what can I use to lube them? Fogging oil, MMO, ATF, plain old oil, sea foam, etc. Previous motors I soaked them in atf but I cant get this motor at 90° to soak the whole cylinder. Input would be much appreciated, thanks everyone!

 

[aMeyers11]

Also I'm aware that wer compression tests give a little higher than actual compression. I just want to make sure the cylinders are lubed before trying to crank the starter.

 

[havoc_squad]

Fogging oil is the easiest to use because its aerosoled two stroke oil.

A two stroke motor cylinder is always wet with fuel/oil, except the top of the cylinder wall above the piston during the exhaust stage of the revolution pushing the piston down.

As soon as the intake part of the revolution pulls in fuel/oil/air, it becomes wet again on the cylinder.

So there's no need to compare dry versus wet compression, because its always wet.

 

[GA_Boater]

So there's no need to compare dry versus wet compression, because its always wet.

Maybe, but the OP said "I'm not sure how long the motor has been sitting". No guarantee the walls are still oiled and he wants to make sure the walls and rings aren't scratched by dry cranking.

Squirt any oil in the plug holes. 2 stroke oil would be fine to lube the walls and rings because that's what will be fed to the motor once it's running.

 

[QBhoy]

Totally agree with GA boater. 100% get some 2 stroke down the bores. Turn over by hand a few times. Feel the plug holes with your thumb for compression. A good table spoon of oil down each at least.

 

[aMeyers11]

I picked up some fogging oil tonight. I will be sure to pour some 2 stroke down each cylinder and then make sure to atleast get the upper half of the cylinder with the fogging oil. It would be alot easier if I had a way to get the cylinders flat, so the oil would distribute evenly, but I'm sure the oil and fogging oil will work just fine. Also thanks for the tip about the wet compression, makes sense. Thanks guys!

 

[GA_Boater]

If you turn the flywheel until a piston is at BDC, most of the wall will be exposed to a spray or squirt of oil. Do each cylinder and turn the flywheel a few more times to smear the walls. You'll be fine with that and minimize the chance of harming the walls or rings.

 

[havoc_squad]

Maybe, but the OP said "I'm not sure how long the motor has been sitting". No guarantee the walls are still oiled and he wants to make sure the walls and rings aren't scratched by dry cranking.

Squirt any oil in the plug holes. 2 stroke oil would be fine to lube the walls and rings because that's what will be fed to the motor once it's running.

I think my answer was mis-understood or mis-read. That is why I said the following:

"So there's no need to compare dry versus wet compression, because its always wet."

My answer was not implying to skip lubing the cylinders before doing the compression test. It was saying the motor is supposed to be running with two stroke oiled cylinders, thus it makes no sense to perform a dry compression test.

 

[racerone]

I think a motor can sit for 10 years and there will still be oil in the cylinder / piston gap to suffice for a compression test.-----Oil in 2 strokes is not a well understood subject !

 

[aMeyers11]

Thanks for all the help everyone. I understand what you're saying about the wet compression now. It's always wet when running so that's all that realistically matters. I will turn the flywheel by hand and try to get each cylinder to TBC and lube the walls with fogging oil. Hopefully I will get the chance to test it soon and let you guys know how it worked, thanks again!