I just purchased this bike out oftheblue from someone with no mechanical knowledge. I recently fixed the bike up, I changed gear oil spark plug, cleaned the exhaust port , also cleaned the fuel supply and the air filter. I noticed there was no head gasket.everything on the bike is stock. In second gear it hesitates also holes were made in the air filter box and I noticed it blows out. I also noticed the adjustment screw on the carburetor doesn't change anything. Also I noticed the baffle tube in the stock exhaust is missing. Any tips or guidance would be appreciated thanks oh also the bike reads over4000 miles possible defective tachometer? I havnt verified that but never the less it's an older bike.