Gx140 piston blow-by normal?

[Mikesbike]

Hello all,

I was tearing down my gx140 today to get a a list going for my mini. So I removed the oil sensor and took the governor parts out. I noticed as i turned the crank there was air seeping by the piston into the crank case. i could hear it hissing. Is this normal for these motors or should I get new rings or something.
last season it ran fine i had it screaming could i have burnt the rings out?

sorry if this sounds stupid but i dont really remember, New rings= honing, new piston= re-sleeved/bore.

any help appreciated thank you.

 

[65ShelbyClone]

You'll probably some amount of blowby hissing like that on most engines that have seen use in their life. Whether it's a problem or not depends on how bad it is. Ideally you would be able to do a leak-down test on it or at least a cranking compression test. Whether the cylinder has to be bored depends on how worn it is. The cylinder will have to be honed whether it gets bored out out or not.

 

[Mikesbike]

thanks for the help.

i realize the motor does run so i might just not go with tearing it all down since this motor is about 25 years old...now that i think about it.

id rather not put so much money in this one besides gaskets and such to put it back together.

I also have 3 other GX motors laying around, two 5.5hp and a 6hp that could be tuned up and started.

I like my gx140 though, im gonna get it going and start with a compression test. i havent been on this site too much is there any guide floating around on doing this, how much compression should i have?

thanks again