Temporary Loud Exhaust Noise????

[Canadaler]

Was out trail riding on my '10 EC300 and when gassing it while rounding a (slightly uphill) corner all of a sudden my bike sounded like the silencer had fallen off. Seemed like it lost power as well.

I reached back with my right hand and yep...it was still there, but I immediately pulled off the trail and shut off the bike. Got off to inspect, assuming that the silencer had separated from the pipe at the stinger...but no.

After looking over the bike and finding nothing wrong I fired it up again and it sounded like I didn't have a silencer....??????

Walked back down the trail to see if maybe the packing somehow got blown out but didn't find anything. About this time my buddies came back looking for me and I started the bike again...still very loud.

After scratching our heads for a while to figure it out...I figured on riding back to the car. Started it up...and no noise. Bike ran fine the rest of the day and on two more rides subsequent to that ride.

Power valve issue maybe? Allowing raw mixture into the pipe where it ignited maybe?

I'm stumped.

[gasgasman]

Yes. Power valve flap sticking.

[Jiikoo811]

Originally Posted by gasgasman

Yes. Power valve flap sticking.

Yep, same happened to me sometimes with 2009 300ec..

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[bkwdc]

Same here. Cleaned a carboned flapper last weekend.

[AZRickD]

What pre mix oil and ratjo are you Sad Power Valve Foulers using ?

[Jiikoo811]

Originally Posted by AZRickD

What pre mix oil and ratjo are you Sad Power Valve Foulers using ?

I used Ipone strawberry smell oil (2%) when had problems with stuck open powervalve. Stop using ipone and change to BradPenn (2.5%) oil and not problem seemed since..

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[Canadaler]

Thanks guys.

Hmmmm....running Ipone strawberry at 2% here as well...makes you wonder doesn't it?

[swazi_matt]

Originally Posted by Canadaler

Thanks guys.

Hmmmm....running Ipone strawberry at 2% here as well...makes you wonder doesn't it?

Must be the sugar from the strawberries

[Jiikoo811]

Originally Posted by Canadaler

Thanks guys.

Hmmmm....running Ipone strawberry at 2% here as well...makes you wonder doesn't it?

After using strawberry ipone i opened cylinder (change piston) and pv. Pv was covered quite hard carbon, not sure how it looks now after using 60hrs BradPenn oil. But at least it work without any issues. We will see that when i change piston somewhere near 100hrs on it...
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[Canadaler]

Always used to use Amsoil Synthetic in my KTM200 with no issues. Might go back to giving that a try.