Ever seen a powervalve do this?

[Boston Racing]

Not sure what happened or how long ago

Looks like the threads are completley gone and the washer is hollowed out.

Any ideas what could cause this? I guess it explains my RPM loss. The bellow was destroyed as well.

 

[SaskRMK]

I had noticed a cap nut on my valve was loose while cleaning them last week. This caused the aluminum lower washer to bore out just like yours. A loose cap nut over time or overt torqing the cap nut (16 foot pounds) could of caused that kind of damage.

 

[Boston Racing]

Guess ill make sure to use a tq wrench and a little red locktite this time

 

[SaskRMK]

Red loctite is a must!

 

[diamonddave]

Is this on the 660??

 

[Boston Racing]

Yep. It has 4600 miles on the motor now. Maybe the turbo pushed it over the edge.

 

[SaskRMK]

How many miles has it been since you have checked the top nut? or disassembled the valve for cleaning?

 

[Boston Racing]

1000 or so. I cleaned them before I put the sled away last season. Every time I clean them..there is not much gunk.

 

[beamslayer]

I just rebuilt a 600 that had this happened too last yr.While we were servicing it for this winter we found the same thing on the pto side.Replaced everthing except the valve add a slp pipe and can and went thru the clutchs, rejettted the carbs sled ran awsome.Less than 50 miles pto side went dowwwn. Top ring caught boost port and broke away top of piston,took out cylinder and head ouch.I may be wrong but I think it built up a lot of heat in the pto side from the ex valve not opening causing the ring to fail.No idea how long he ran it with the bad ex/va. I looked at the cylinders while doing the servicing they looked good.
If I see this again I think I would change rings they are alot cheaper than what we just did.Just my peso