DS 90 bogging on acceleration

[poppaquad]

My family has an '07 DS90 four stroke. We bought it new, and it had all the power you could want. Unfortunately, it sat about a year without draining the fuel, and when I got it going again, after draining the old gas, refueling with new, it would start hard, and run poorly. I have removed the carburetor 5 times, and cleaned it each time. Now it fires up nicely, but when you ride it, it takes off fine, then falls on its face with a bog, and to keep it running, you have to modulate the throttle. When this happens, I can choke it, and it seems to help. I've replaced the pilot with a factory replacement with a different number (?), checked the air cleaner (fine, but oily), checked and cleaned the screen in the muffler (fine). I'm at my wits end at this time. Any help would be appreciated. The ATV only has about 10 hours or so on it, and my Granddaughter is getting miffed that her bike won't climb hills. Thanks

[cammoquad]

Have you had the valves rechecked since new ? if valves aren't set right it will mainly be hard to start but will also affect running
Check the clutches on the cvt drive they are probalby dirty not allowing rollers to slide or not allowing it to get up to speed ,not a hard job
if i think of anything else will post later