Yamaha’s solution was to add an extra tooth to the rear sprocket (changing last year’s 13/48 to a 13/49), which made the final drive ratio a 3.769 instead of a 3.692. It helps if you have a scorecard handy, but to recap: Yamaha lowered third gear, raised all the gear ratios via the primary gear, and then lowered all the gears with the rear sprocket. Maybe it is just us, but we tend to think that the extra 3 horsepower in the YZ450F’s midrange would have solved the gap issue between second and third gear without all the cog shuffling.
THE CHOKE KNOB IS NOT WHAT IT SEEMS The choke knob on the side of the throttle body may look like a choke, but it isn’t. The knob on the side of the throttle body increases the amount of intake air that goes into the engine. You use it when the engine is cold and not when the engine is hot.
WHY ISN’T THE MUFFLER RUBBER-MOUNTED? The right side of the aluminum subframe is an extreme scalene triangle, with two long sides and one narrow side, but none of them equal. Yamaha had to pinch the shape of the subframe down to make room for the muffler to be moved 188mm ( 7. 3 inches) forward on the chassis. The muffler is solidly mounted to the subframe at the rear and the frame at the mid-pipe. Why isn’t it rubber-mounted? Because the exhaust pipe is structural to the subframe, which means that the pipe itself helps support the rear fender.
WHAT IS THE BEST GEARING COMBINATION? We wish we knew. Since Yamaha has played tic-tac-toe with the gearbox for 2014, we tried every possible combination from 48 teeth to 51 teeth. For fast tracks with long straights and lots of room, we stuck with the stock 49. It is important to remember that the 2014 YZ450F’s 49-tooth sprocket isn’t the same as putting a 49 on the 2013 YZ-F. Nope, the new 49-tooth sprocket is more like last year’s 48-tooth sprocket (because of the primary gear change). Thus, if you want to gear the 2014 YZ450F lower to make better use of third gear, you will need to go to a 50-tooth sprocket. Most MXA test riders preferred this gear combo for racing. At one point we hypothesized that going even lower, to a 51, would allow us to use third gear more and close the gap to fourth gear, but all it really did was make second gear too low without enabling third gear to replace it.
WHAT WAS OUR BEST MAP? If you read MXA’s 2014 Yamaha YZ450F test a few pages earlier, you know that we had major issues with the fuel and ignition mapping. No surprise! Last year we remapped the YZ450F to eliminate the irritating bark off idle. And since the 2014 YZ450F has the same bark,