3120 Scuff

[ManBehindTheScene]

Just picked up this 3120xp for a milling rig. Piston has some scuffs, doesn't really look like any transfer. I was thinking about pulling the jug and checking that there is no transfer, chamfer the exhaust port and maybe a new set of rings, possibly a new piston. It blows close to 150#. What would you do?

I've heard some bad things about the stock pistons having the locator ring back out and trash the top end. Is that a prevalent issue or no? Maybe CCC Racing has a Wiseco piston that's a better option? What's your thoughts?

 

[Labfab]

Just picked up this 3120xp for a milling rig. Piston has some scuffs, doesn't really look like any transfer. I was thinking about pulling the jug and checking that there is no transfer, chamfer the exhaust port and maybe a new set of rings, possibly a new piston. It blows close to 150#. What would you do?

I've heard some bad things about the stock pistons having the locator ring back out and trash the top end. Is that a prevalent issue or no? Maybe CCC Racing has a Wiseco piston that's a better option? What's your thoughts?

Piston is in backwards. How it hasn't snagged a ring yet, is incredible. Chamfering must be really good on that cylinder.

 

[ManBehindTheScene]

Piston is in backwards. How it hasn't snagged a ring yet, is incredible. Chamfering must be really good on that cylinder.

As far as I know, it's all factory. If its backwards the factory screwed it up. I've never been into a 3120 so it never crossed my mind that it's backwards.

 

[BayouCountryPowerSaws]

As far as I know, it's all factory. If its backwards the factory screwed it up. I've never been into a 3120 so it never crossed my mind that it's backwards.

Ive never seen one either so I wasnt going to say anything, but I was looking at pictures of cylinders wondering why the pinned those rings in that location

 

[ManBehindTheScene]

It got great compression but if you zoom in, that upper ring has heavy wear chamfered on the upper and lower edge near the pin.

 

[Labfab]

As far as I know, it's all factory. If its backwards the factory screwed it up. I've never been into a 3120 so it never crossed my mind that it's backwards.

Haven't heard of any 3120's with factory backwards pistons, but there were lots of 390's that made it out that way. It's absolutely backwards though.

 

[Bjorn T]

Ccc, racing pistons is very nice. Good quality and made by wiseco. It is Also a singel ring piston. So one problem less, that can ruing your cylinde.

 

[jasent]

Yup backwards. I’d pull the cylinder and replace piston and caber rings. Looks like that upper locator pin is already backed out some. Hopefully the jug isn’t damaged.

 

[ManBehindTheScene]

Ccc, racing pistons is very nice. Good quality and made by wiseco. It is Also a singel ring piston. So one problem less, that can ruing your cylinde.

Only one I found was an oversized piston for 62mm. I'll have to reach out to Dave. Is he on the forum yet?

Yup backwards. I’d pull the cylinder and replace piston and caber rings. Looks like that upper locator pin is already backed out some. Hopefully the jug isn’t damaged.

I doubt there is any based on the 150# compression. I dont think the pin worked out any but the ring end has been taking a little beating based on the wear.

 

[jasent]

I could be wrong but it looks odd to me.

 

[ManBehindTheScene]

I could be wrong but it looks odd to me. View attachment 68

Yeah, I'll know more when I take it apart but that looks (to me) like the end of the ring opening up and coming out of the ring land when over the port, not the locating pin backing out.

I might stick with an OEM piston with dual rings for this saw since its going to see heavy use milling. If it was a toy then the single ring CCC piston would be a no brainer...

 

[BayouCountryPowerSaws]

Only one I found was an oversized piston for 62mm. I'll have to reach out to Dave. Is he on the forum yet?

Not to my knowledge as of right now.