I have problems keeping the bike running on a regular basis, ive cleaned jets drained gas and put new in and all other basic stuff, sometimes it wont run for weeks on end then start running again,or sometime just keep kicking or cranking for about 20 min then it will kind of burble then die and the only way ive found to get it to run correctly is bump start in second gear and NOT STOP RIDING until it runs without stumbling any idea on what it could be?