Top end noise ?

[Link]

On de-aceleration there is a loud rattle type noise I think coming from the cyl. head at first I thought it was the pipe guard or the pipe springs but with the bike on the stand I was holding onto the pipe trying to find the cause of this noise and it's not the pipe. Could it be the power valve ? The bike runs great and sounds fine on the gas this noise only happens after quick shut off of throttle Bike is an 06 EC 250
Thanks

[Brian VT]

It's most likely just the chain slapping on the swingarm slider.
They all do it. It's unnerving but no harm. Many posts here about it.

[Link]

No, I heard the noise when riding so I but the bike on a stand in neutral and the noise is loud it's not chain slap
Thanks

[GMP]

The PV will rattle but its normally not excessively loud. If your pipe o-rings are bad (worn from vibration) that can cause vibration noise, did on my '07.

Remove the right side PV cover and run the bike. See if the actuator plate is vibrating against the stop bolt when you hear the noise. The plate shoud touch this bolt with very slight preload with the engine off.

[Link]

I just replaced the O-rings but I think there too small as it's leaking at the pipe connection so I will sort that out today & try your suggestion. Maybe the rattle I'm hearing is normal. I have never owned a 2 stroke with a PV
Thanks

[GMP]

When you remove the pipe, look at the edge of the header connection for wear marks that indicate it was vibrating against the spigot bolts. Thats what happened to mine. It was very loud, but difficult to see. Use the correct o-ring.

[Brian VT]

Originally Posted by GMP

Remove the right side PV cover and run the bike.

You'll need to grind an allen wrench shorter to access the bolt(s) without taking the pipe off.

[Link]

FIXED....I went to the auto parts store & used 44X4 O-rings it was a real tight fit I had to smack the pipe with a rubber mallet a few times to get er on but the noise is gone!! now there is only a faint rattle of the PV that GMP mentioned. Thanks again for the help.