Dark Ring in Cylinder wall

Tracy Meade /
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Hey everyone,

This happens sometimes on my cylinders, Never thought much of it, but figured I would ask what to make of it.

Newish kit, after a few break in rides, gave it about 10 miles worth of WOT then broke it down to check out how she looked.

Temps were topping at about 380-390.

Got this pretty dark ring around the top of the cylinder.

Otherwise cylinder/piston look fine.

Is this normal/fine or trying to tell me something.

Re: Dark Ring in Cylinder wall

That's where your ring is at tdc.

Re: Dark Ring in Cylinder wall

Your squish isn't set right most likely. It's sitting awfully low.

Did you measure squish?

Re: Dark Ring in Cylinder wall

Tracy Meade /

I did.

There is a gasket in the pic possibly making it look lower.

But piston dome sits almost flush with top of cylinder.

Re: Dark Ring in Cylinder wall

What is the squish

Re: Dark Ring in Cylinder wall

Cuz generally the crown should be above the deck if you have a good .8mm squish (edited)

Re: Dark Ring in Cylinder wall

Tracy Meade /

I measured 1mm

yes, the crown is higher than the deck, I meant that the edge of the piston is about flush with the top of the cylinder.

Re: Dark Ring in Cylinder wall

Tracy Meade /

The question was a bit more generic though — about the existence or lack thereof a dark ring on the cylinder wall.

Re: Dark Ring in Cylinder wall

The dark ring is normal. It's just where the ring stops at TDC

Re: Dark Ring in Cylinder wall

Yep normal

Re: Dark Ring in Cylinder wall

Tracy Meade /

:thumbs

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