My bikes a 2009 ktm 150, I've just had the engine completely rebuilt apart from the gearbox.. It's had:- Cylinder replated Piston Conrod Bottom end / big end bearings clutch plates Clutch basket I've been running the bike in for 3 hours now, I Havnt hit powerband until I hit the 3 hours.. I then started going through the gears at about 3/4 throttle, and all seemed great.. Pulled like a train.. Until I slowed down, went to accelerate again and it was completely flat and the engine note completely changed.. At first I thought the exhaust had come away at the joint between the header and the pipe.. But that wasn't the case, I then rode again, hit the power, all was fine, pulling like a train again, I slowed down again, went to accelerate and again it was totally flat, no power at all and the engine note had changed again.. So I then thought the power valve was sticking wide open.. But I've just taken the barrel off, checked the power valve and cleaned it all and all seems perfect so I don't think it's the power valve, I just put it back together took it for another ride and its still the same.. Does anyone have any advice? I'm at my whits end.. 2 months and £900 later and I still can't hit the tracks!