my 92 tomos top tank is sputtering bad enough in second gear to mak the moped only go like 20, but if i get going fast enough, it will stop sputtering and run normally. if i an going up a small hill and it shifts into second just barely, it will die out. Is this water in the gas? Also, is there a lockable gas cap for the top tank tomos? (just in case someone does put water in the gas to be an asshole.) Also, what about a cap that seals better? thanks!