High speed bump performance change?

[lvermey]

Hi 2t gurus, I need some help. I have a new to me EC300 08.

The fellow I bought the bike off of told me the float needle jet was leaking. I fixed that by just cleaning it out. Checked the float level and it was at 16mm. I got that measurment from the carb site. Then on my second ride I was going down a trail in 4th or5th gear at a good clip but not on the pipe, say mid rpm range. Then when I hit a 3" to 6" rock or root the exhaust note would change to pap pap pap... and I would lose half of my power. So I backed out of the throttle, shifted down, then rolled on the throttle until I hit the pipe and it seemed to correct its self. Doesn't do it every time, but anytime is to often.

The only things I can think of are: Carb, exhaust valve/power valve ( are these the same thing?) or reed valve?

I hope some one can help!

Len.