The Yamaha Raptor YFM660R began life during what is viewed as the ATV world's most recent revival. Manufactured from 2000-2005, the Yamaha 660R Raptor quickly became the ultimate sport quad, boasting what was then considered a massive engine, the notorious 660cc powerplant it inherited from the German MZ Bahira 660 dual sport off-road motorcycle. Though primarily stuck to using only the head and cylinder of the motorcycle, the chief design engineer of the cutting-edge ATV project, "Knobby" Shiraishi, had the insight to enlist the same technological advancements used in the fledging YZ426F dirt bike as well as the R1 and R6 street bikes. While the Raptor 660R 4-stroke engine only used a single overhead cam, it was liquid cooled and did boast a five-valve for its big bore cylinder. Within the cylinder, the piston and rod forged a lightweight package with a 9.2:1 compression ratio and bore and stroke of 100mm X 84mm. The combo provided for a quick rev that bit considerably better than most four-stroke motors and topped the rev limiter of many of its day at a whopping 9000 RPM. And smooth she was with an engine counter balancer and torque that projected smooth but inspiring power throughout the power band. The major downfall of the mighty Raptor 660R was its weight, nailing the needle on the scale to the 398 pound mark. This was nearly 25 pounds heavier than Yamaha's closest competitor, the Honda TRX400EX, which was relatively light, nimble and extremely reliable. About the only thing that may have saved the Raptor 660R from becoming a handling nightmare was the front to rear weight ratio. Out back, the Yamaha Raptor touted 54 percent of its weight, while the front boasted 46 percent. Combined with its brute power, lifting its nose to the air at the competition wasn't a problem. It was a snooty beast on the sand dunes of Glamis as well as in the flats of desert. But here's the problem, it was narrow and considerably top heavy because of this. The Yamaha Raptor was thin for its weight and overall size at 43.1 inches wide. It closest competitor was again the TRX400EX, which logged in at about 45 inches. While this might have made the Raptor nimble enough for pulling duty in the tight woods, the narrowness was often considered a hazard for ventures in the desert or at the MX track. Most certainly, wider axles and wider A-arms were the top parts of choice for those looking for any form of performance from the Raptor, and the Roll Design package was amid the most sought after of the lot. Likewise compared to the TRX, the YFM660R was 49 inches, which was only a half-inch longer. Therefore, a longer swingarm was definitely in order for most riding. For these reasons, the Raptor fell considerably short and was often the excuse for many crashes, where riders simply ran out of talent.