I picked my son up a 2004 pw 80 recently. I live in Denver where the altitude is 5200 feet. The bike never ran very good from day one, always bogging and running rough. After researching some 2 stroke sites I rejetted the bike with a 120, got rid of the oil injector, and messed with the screws on the carb a little. I also dropped the needle clip one notch. The jet I pulled out was an 85. Now the bike runs fairly well with the choke on but will not run with the choke off. Its frustrating and im about ready to get rid of the bike. It doesnt have that many hours on it so I assume it is just jetting. Is a 120 ok for the altitude? I think stock is 125. Please help.