I just picked up a 78ยด dt400 and it starts up and runs fine but after a minute or two the engine bogs down and the rear tire locks up. I pull over and it starts up after a kick or two and I take off and it does it again. Any ideas of what it could be? Also, anybody know what the cable in the front of the cylinder does? It looks like it goes into the case. Some sort of compression release? Any info would be greatly appreciated. Thanks,