I have a 99 yz 400 F. It smokes on start up and the carb seem finicky. I have just done a valve job and rebuilt the carb. I live at sea level and dropped the needle clip on groove to allow more fuel due to cold temps. Carb has always been finicky. I want to sell the bike, but need to know if the problems I see are common or not. I have done everything I could think of to elliminate acceleration lag. HELP.