Hey there, I bought a used 2003 Honda CR250R last summer and since the day I bought it, it is very very boggy bottom end. I trail ride the bike and so when going through tight single tracks when i cant get the rpms up, it will bog. But when i get out to a open stretch of trail, and get the rpms up and shift through the gears it is perfect! I did a top end rebuild over the winter changing piston, rings, gaskets hoping this would fix the problem but it is still the same. I had a Honda mechanic do a tune up on it (adjusting the carb and new spark plug) a couple weeks ago and it is still the same if not worse. He also said that my plug was reading perfect, he has never seen a more perfect burning 2-stroke in his life. I have read on some other threads that it could be the crank seal leaking?? I checked my trans fluid and it was low about 1/4 - 1/3 liter. I also say it seems to run too cold because after a long ride in the trails, the second i shut off my bike, i can hold my hand on the engine. it is not hot at all!! Any help is greatly appreciated, I could deal with it before but it is so annoying now and I have spent piles of money trying to figure it out. Thanks!