It appears you're interested in specifications for the Yamaha GT80 B. This Enduro / offroad model is powered by a Single cylinder, two-stroke engine with 72.00 ccm (4.39 cubic inches) of actual displacement before 6.0:1 compression. Fueling is metered via Carburettor. Teikei allowing this machine to produce its 4.90 HP (3.6 kW) horsepower and 6.10 Nm (0.6 kgf-m or 4.5 ft.lbs) torque. According to our records engine heat of the Yamaha GT80 B is moderated by Air. You'll need to get familiar with the 4-speed transmission and pay attention to final drive Chain maintainence. Our best information shows that the front tire size is 2.50-15 and the rear is 2.75-14 . The entire package is supported by the frame, Steel. We know you like to go fast or cruise all day, but when you need to stop, you'll be dependant on Expanding brake (drum brake) front brakes and Expanding brake (drum brake) rear brakes. The Yamaha GT80 B was launched in 1975, and we're happy to know (or assume) you've got one in your garage. To help you keep your ride in tip-top shape, consider purchasing an owner or service manual.