6 cube 066

[Deets066]

Is it possible that between the clearance with bore and the compressed o-ring you're not getting the heat transfer at the top of the cylinder that you do with a 1-piece cylinder?

Is the o-ring totally compressed or is it acting as an insulator?

Almost fully compressed but still an insulator.

I'm sure the head heats up faster than the jug but it's the piston to jug relationship that really matters in this scenario I think

 

[Termitebuffet]

That's a possibility, but I couldn't imagine what that would be, I'm very anal about internals being clean when I assemble. And for sawchips to do that is unlikely right?

Left side of picture between exhaust and transfer, horizontal lines ...is that oil or an optical concussion

 

[Deets066]

Left side of picture between exhaust and transfer, horizontal lines ...is that oil or an optical concussion

Oil

 

[thomas1]

Almost fully compressed but still an insulator.

I'm sure the head heats up faster than the jug but it's the piston to jug relationship that really matters in this scenario I think

I was just thinking that with the o-ring acting as an insulator you may not be conducting as much heat away from the cylinder wall/piston as you would normally. Just brainstorming and I ain't workin' with much up there.

 

[Deets066]

I was just thinking that with the o-ring acting as an insulator you may not be conducting as much heat away from the cylinder wall/piston as you would normally. Just brainstorming and I ain't workin' with much up there.

I would think it would be better to insulate the head from the jug. As the small head with little to no fins would put more heat into the cylinder than normal.

I think.

 

[thomas1]

Pressure/vac test?

 

[Deets066]

Pressure/vac test?

No I haven't, it seemed to tune and idle pretty nice. And that's a rarity with a big carb.

You can bet I will before it goes back together though.

 

[Deets066]

I've seen saws run way lean for multiple cuts.

This one made 4 cuts which makes me think it's a clearance issue.

I'm gunna check piston to jug clearance tomorrow

 

[Stihlbro]

You are on the right track.

 

[Sty57]

View attachment 89744

To my untrained eye, it looks like a cold seize in snowmobiles. Where everything hasn't come to temp and stabilized before a load is put on it.

 

[Sty57]

Is that piston cast or forged?

 

[thomas1]

I would think it would be better to insulate the head from the jug. As the small head with little to no fins would put more heat into the cylinder than normal.

I think.

To my untrained eye, it looks like a cold seize in snowmobiles. Where everything hasn't come to temp and stabilized before a load is put on it.

Maybe I was backwards, possible that the head was sucking heat from the top of the bore and it didn't expand fully, yet?

Did you tighten the head down in any sort of steps or pattern?

 

[Deets066]

Did you tighten the head down in any sort of steps or pattern?

Tried to be as even as possible when I tightened it. Jumping back and forth several times

 

[Sty57]

forged piston has to be heat-cycled several times to relieve the internal stresses left over in the metal from the manufacturing process. If this isn't done properly, the piston will distort and become out-of-round, causing it to wedge itself into your cylinder.

 

[Termitebuffet]

To my untrained eye, it looks like a cold seize in snowmobiles. Where everything hasn't come to temp and stabilized before a load is put on it.

I 2as thinking cold seize , but it's most 4 corner ...is that what u see in snow machine?

 

[thomas1]

Tried to be as even as possible when I tightened it. Jumping back and forth several times

Be careful when you jump back and forth, you could accidentally slip and crack your noggin, if you're not wearing your helmet.

 

[Deets066]

Is that piston cast or forged?

Forged

 

[Sty57]

I 2as thinking cold seize , but it's most 4 corner ...is that what u see in snow machine?

The ones I have seen and have done it to. Have had scuffing all the way around but mostly on the Ex side.

 

[Sty57]

Forged

Mic the piston and see if its still round. You have to break them in slow and put them through some heat cycles when new.

 

[Mastermind]

Thanks for taking the time to share Deets.

Very cool.

You'll get it figured out.