Whaddya reckon to these marks I've noticed inside my cylinders?


Cylinder Pitting2


CylinderPitting1

On the second picture there's a slight scratch which you can just feel but in general there is a very slight sort of pitted effect. Its not very prominant and you can't even feel the 'pits' but there is a slight raise there. I've tried cleaning them with thinners by the way.
I suppose my uestion is what problems are these likely to cause if any?

very difficult to tell from pics but if the bores are not excessivley worn i would try honeing them and see if the marks are just on the surface

I've just thought as to the cause. The engine was sat under a tarp for a while when I bought it and had a bit of water in the cylinders then but not sure about that slight scratch.
I'm thinking of honing them down the line but I may try something like some fine paste or polish first. Any suggestions.

Are the pics looking down into the cylinder or up from underneath the cylinder.

If looking down the cylinder then the circular scratch mark could be a ware line where the piston rings getdown to but not any lower.

Paul

hone the bores and fit new cored rings that should be okay. Just honing and using the same rings may allow oil to pass

Hey I like your thinking there Paul. The view is from the top looking down. Both marks are coincidentally 40mm from the top and the whole cylinder is 90mm.
I've just measured the pistons and there's a 40mm difference in the rings

Are these wear marks normal then?

I'd have said definately water marks.

I'm inclined to think that too not sure whats caused the very slight scratch that you can see in the second picture though.

Is it definately a scratch?? could it be where the ring was rusted to the bore and a bit has come away?? I presume you mean the dark mark around the centre of the bore?

I mean the line through the dark mound. I suppose its possible that that was the bit protected by the piston ring and rust marks have formed around it, so yes.
I'm beginning to think its not much to worry about now thanks to Pauls suggestion.

Use a three stoned honing unit. Use the springy ones in a drill and don't pull the decise out until it's stopped spinning!!
I definately looks like the pistons were sat at. There will probably be a pair of cylinders the same. One and four or two and three.
At that point in the bore, the surface has to be spot on as that's the 'turnaround land' that gets the most wear from the rings. The bores get the most wear from lateral wear midway when the rods are pushed at an angle to the bore line.