my bike bogs out when I ask it to do a little heavy lifting (going up a steep rocky hill). This has happened a couple of times over the past couple of years. Only seems to happen when i really need some power to climb. It will bog out and die. It always sluggishly starts back up after a minute or two rest. And i noticed fuel coming out of the overflow tube at bottom of bike this last time. Anyone have a solution for this problem?