Scratches on intake side of jug

[trimmmed]

This jug is off a JD 65(echo 650evl) The exaust side is fine on the jug and piston, but there are some good scratches on both on the intake side. What causes this? Is it dirt getting in or something mechanical? This saw was more than filthy to start out with.

I have another jug and piston, they are perfect but there is some carbon on the piston top and the top of the cylinder. Anybody got a trick for cleaning that stuff off in particular the cylinder?

Thanks

 

[canguy21]

You are on track. Scratches on the intake side often indicate poor a/f maintenance.
Try oven cleaner on the carbon but use good rubber gloves. That stuff burns.

 

[NevadaWalrus]

Just a couple of scratch's could also be flakes of carbon that broke off and go stuck between the piston and cylinder.

Look close at the piston. If the area of the piston that is exposed to the intake port has a dull appearance compared to the rest of the piston it has indeed been "sanded" by dirt injestion. If not, carbon flaking or one or two pieces of grit got in there causing the scratch's.

 

[Crofter]

Have read that sucking in snow can cause intake side scoring; seeing where you are from though it is more likely dirt than snow.