I can start it up just fine but when i give it throttle the engine just revs i bought the bike 3 days ago and it was running great i was riding and i poped the back tire and i replaced it and got one good run and then it started doing this i figured it was because it was low on fuel so i filled it up and still it wont move without pedaling lol i also thought the throttle cable could be loose but it still revs i also noticed if u turn the little lever thing the gas leaks but if ur turn it the other way the gas sits in the tube. the gas leaks alot and makes puddles on the engine. I noticed theres like grime in the cracks on the engine where it comes apart should i open it up and clean everything out?