Somethings leaking! Rings? Piston? Cylinder?

Hey there! I decided to do a rebuild on my pug motor to put on new gaskets, remove the exhaust port lip, new intake manifold, and new Athena reeds. it ran great but when i got it dismantled and the exhaust taken off, there was some kind of leaking past the rings. through the exhaust port i can see the air bubbling in oil when i turn the engine over. like I said it runs great so maybe this "leaking" is normal because when i turn it over slow, there might not be enough pressure to force the rings out tight. IDK i haven't tested the compression yet cause i don't have the tool to do it with but i plan on ordering one soon. the cylinder and the rings both look good and smooth, not scratched up or anything. basically I would like to know if this is a problem and what I need to do/buy to fix it.

Thanks Guys!

also i will post a video right after this...

Re: Somethings leaking! Rings? Piston? Cylinder?

If it runs great , why are you messing with it ?

Re: Somethings leaking! Rings? Piston? Cylinder?

It's fine.

Re: Somethings leaking! Rings? Piston? Cylinder?

Caleb, If you intend to keep working on motors, a compression tester is a pretty important tool to have.

Re: Somethings leaking! Rings? Piston? Cylinder?

gonna get alotta slack for this but here goes. a compression checker is unecessary... you should be able to tell just by spinning the motor by hand listening and feeling. u either go ohhh damn this is hard to turn, thump, thump, good compression, or somewhere in the middle hmmmm normal or shit this is easy to turn, hard to start, low power, damn gotta open up.

Re: Somethings leaking! Rings? Piston? Cylinder?

> pat splat Wrote:

> -------------------------------------------------------

> gonna get alotta slack for this but here goes. a compression checker is

> unecessary... you should be able to tell just by spinning the motor by

> hand listening and feeling. u either go ohhh damn this is hard to turn,

> thump, thump, good compression, or somewhere in the middle hmmmm normal

> or shit this is easy to turn, hard to start, low power, damn gotta open

> up.

That's true, pat - if you are experienced in these matters.

Re: Somethings leaking! Rings? Piston? Cylinder?

Richard Eberline /

No test equipment, very limited on toolssss and weak on knowledge. Get help in your area, of a pug mechanic.

Re: Somethings leaking! Rings? Piston? Cylinder?

Josiah Radebaugh /

I feel like if it runs and gots thee power expected just leave it. And maybe s once the rings are new(?)

Re: Somethings leaking! Rings? Piston? Cylinder?

Ok! I think i'll just leave it. might eventually do rings and a cylinder hone, but for now its gonna stay as is. I did order a compression tester anyway. just curious. its not an super expensive tool or anything and will maybe be useful in the future.

I've been thinking about it and it seems like since it went right around 25-30 bone stock, this leak probably isn't a problem since the wiki says the 103 u3 (my model) has a top speed around 30ish mph. with the new reeds, derestricted intake and exhaust, bigger carb, and exhaust port lip gone i'd like to see 35-40 mph but we shall see. if any body has any tips for my stockish setup Let Me Know! Thanks!

Re: Somethings leaking! Rings? Piston? Cylinder?

Hey man I’m not too far from you if you wanted to swing by we can check it out. I’m not a big fan of compression testing because it doesn’t give you the full story. Leak down testing the engine is much more valuable information.

You could have a leaking decompression valve causing your issue.

Look into removing weights from the variator and adding a launch lever. You’ll have a blast with that set up

Re: Somethings leaking! Rings? Piston? Cylinder?

Hey! Thanks Neil for the offer! Might take you up sometime but for now I'll keep truck'n.

So You asked fro it and here it is. the results of the compression test. at wot turning over with a drill, I'm getting about 125 psi of compression according to my gauge. its a cheap gauge, so you can take the measurements for what their worth. For comparison, i tested my 66cc engine and got right about 188 psi. both measurements make sense to me because the Peugeot cylinder is stock except for slight exhaust porting. the other engine has significant porting and head-work done on it.

Re: Somethings leaking! Rings? Piston? Cylinder?

125 lbs. seems pretty good. Now you have a baseline for comparison should you have any issues down the road.

Re: Somethings leaking! Rings? Piston? Cylinder?

♣Slew Foot♣ /

Piston oriented right?

Just for MacGyver's

Take off head insert and screw in truck tire stem use tire gauge.

Re: Somethings leaking! Rings? Piston? Cylinder?

i lapped my comp release & my leak stopped...

they suck & they blow...just sayin'

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