Low compression

[Jason. Blake46]

Hey yall, I have an echo cs400 it stopped running, I checked the compression, it was 30psi. So I tore it down the ring was stuck in the piston, so I replaced the piston and ring and it's still getting 30psi. I checked and confirmed my compression tester is good. I know this is a cheap saw but I'd love to learn on it and get it going again. Now when I put air to the spark plug hole with the intake and exhaust plugged it bubbles out the crank, im just not seeing how that could cause low compression. If yall think it's that could you explain the why?

 

[ammoaddict]

So you keep pulling it until the guage stops climbing, and it maxes out at 30psi?

 

[grizz55chev]

Hey yall, I have an echo cs400 it stopped running, I checked the compression, it was 30psi. So I tore it down the ring was stuck in the piston, so I replaced the piston and ring and it's still getting 30psi. I checked and confirmed my compression tester is good. I know this is a cheap saw but I'd love to learn on it and get it going again. Now when I put air to the spark plug hole with the intake and exhaust plugged it bubbles out the crank, im just not seeing how that could cause low compression. If yall think it's that could you explain the why?

How much air are you using, and is there a valve in the end of the compression guage?

 

[Jason. Blake46]

So you keep pulling it until the guage stops climbing, and it maxes out at 30psi?

Yes

 

[L34]

Did you clean up the cylinder?
No mention of this.

 

[Jason. Blake46]

Did you clean up the cylinder?
No mention of this.

I wiped it down

 

[Jason. Blake46]

Update, I tore it back down, the rings they sent were to thic for the piston so me in my infinite wisdom decided to lad .3mm off them. Well without thinking i took a little off each side, didn't even think of the end gap pin. Well it's getting stuck under that. So ordered a new piston and rings

 

[Gord404]

would suggest to do the seals if its bubbling out the crank or it will just end up the same way again.

 

[Jason. Blake46]

I was thinking about it. But I can't find them anywhere

 

[mountainlake]

Seals https://www.sepw.com/cart.php?suggest=0ed8ba22-5a5e-4306-8e18-5022a368937b


Steve

 

[Gord404]

before I took down a 660 a couple of days ago I wanted to find out what caused the damage to the piston so I have a good start... Boot leak... will give it another vac a pressure check when the new piston and clean cylinder go back down.

 

[Jason. Blake46]

Seals https://www.sepw.com/cart.php?suggest=0ed8ba22-5a5e-4306-8e18-5022a368937b


Steve

Awesome thanks, I've been googling for a few days and couldn't find anything.

 

[mountainlake]

Also these are oem parts, a new oem piston with rings is $38. Steve