I just picked up a 81 250 XT Yamaha w 4000 miles on it. It is in great shape considering its age. I´m not a machanic but I took it to a friend to help me get it started. It has sat for a long time in a barn. We changed sparkplug,gas, and cleaned the carburetor and still can get it to fire. We even sprayed so ethor in the head and still it didn´t fire. It is getting gas! I tried it with the swith in the on and off position! Any suggestions? Please help!