i just bought a 2002 400ex with a rebuilt 2004 400ex motor...it has been completely redone...aftermarket piston,cam,clutch,valves and ported and polished...new carb also...anyway the fourwheeler starts fine but when you hit the gas it sounds like its really bogged down until you hit mid to high rpms...even when you ride it its really lagging until you hammer on it then like a second and a half it comes to life...upon inspection we found gas all in the oil...we checked the spark plug and it looked like it was burning perfect...we tried adusting the carbs but no change...we checked the cdi with an aftermarket one but still no change...we took the exhaust off and it still did the same...but anyway when we changed the oil and put the spark plug back in it ran perfect for about two minutes...then the same stuff again...what to do...please help...