01 honda cr250 put new gas and plug running 40:1 tried racing fuel made it worse so I went down to mid grade fuel got a little better. Every thing is stock. Bogs at high rpm wheb I revved it ouy and lurches at low speed. Idle sounds like its puting around just to stay on. I am thinking its carb thinking of getting the kehin carb prejetted from carb part warehouse on ebay. Previous owner only used it for trail riding and compression is good starts first kick.