Rotary Valve cover - damage or normal?

[seasoned]

In dissassembling my SBT motor for return under warranty, I pulled the rotary valve cover off to notice significant scuffing on both the motor and valve... along with the cover.

The "damage" is circular around both sides.

Is this normal or is this something which will need to be replaced. When this motor was installed, I ihad the mechanic nstall a remachined rotary valve cover and rotary valve.

On top of that, if I purchase the new valve cover and valve from SBT.. can they install and time it prior to shipment of new engine?

[seasoned]

Also forgot to mention... that from looking through the openings.. I can see that the front #1 piston ring broke off.. which seems to be the reason for failure.

[Bryan Glynn]

Yes we can time and install a valve and cover. Where was the cover remachined from the last time? Is the damage only on the case side of the valve or the cover also? Circular scratches indicate either a dented valve or debris going through. Bad clearance, a bad chamfer, debris, or severe detonation are common causes for a ring to snap. It has to be broken down for inspection to get an accurate cause.

[seasoned]

Cover also. The debris seemed to be from the broken piston ring.

Dented valve?

One of the ones my mechanic had. I assume it was re-machined by the Jetski doctor in Ft Lauderdale....since he does most of his own work.

Severe detonation? I noticed on the bottom of the motor - a spot about an inch wide where part of the seal was gone... which would cause an air leak and might cause detonation? I took a look at the pictures to piston damage and it actually looked somewhat like regular wear with just a broken ring.

Ski was running "ok" for several months. Always hard to start in the water.

Carbs were rebuilt and adjusted when motor was installed.

[Bryan Glynn]

It's certainly possible debris came out and scored it. Dented valve as in debris coming in and catching it's edge.

Yes a bad seal will cause detonation under the right circumstances.

Was the clearance of the cover checked when it was installed? Not that that would cause ring snag, but it's necessary to check if the cover has been altered...

[seasoned]

My mechanic assures me everything was checked and taken care of.