EC300 exhaust note
 

Excuse my ignorance if this is normal please!
Have just had my 08 EC300 jetting sorted.
The bike actually gets on the pipe now, and very easily - talk about a different bike.
Opon my first ride on the new improved machine, i noticed when on the pipe and staying on it the exhaust note changes. (actually stopped to check the end was still in the muffler)
The note will go back to it's normal (nice) sound about 30 secs after going back to lazy mode.
Any thoughts please?
PS. also put the larger power valve cover on if this has any bearing. (can't say i noticed any difference yet with the cover)

Without being able to hear it it's impossible to know what sort of noise you're talking about. But ... yes the note does change when it gets on the pipe as all 2 strokes do. Normally they get louder and sharper sounding.

If it sounds like an open header, it could be the power valve sticking then abruptly opening.
A friend of mine has an '08 300 that was doing the same thing.

The actuator rod was binding at the power valve actuator pivot.

Mine did that once, scared the s*** out of me as I thought I had blown the engine even though it was still running. Shut it off to check it over and found nothing. Restarted it and it has been fine ever since (happened about 5 years ago). I always wondered what the cause was and nobody else seemed to have had it happen to them at the time.

Yes, sounds are hard to describe. it does change to a loud sharp crackle like a motor cross muffler. my concern is that it stays that way for a couple of minutes even after pulling up and just fettling the throttle.
the power valve was shimmed when the jetting was done. mechanic said it had a lot of play. But on reading on this and the Ausie forum most 08's seem to have the play.

Sounds to me like the power valve is not moving freely and is sticking in the open position. Maybe it's shimmed too tight. Neither my 2000 or 2005 EC300s needed it.