84-86 YAMAHA YZ250: FMF Fatty Pipe - 2-Stroke With well over 35 years of racing experience behind it, the Fatty pipe delivers race-proven performance. The Fatty broadens and smoothes out the power curve while boosting gains throughout the entire power band, more low-end, more mid, and increased over-rev. No matter what type of riding you do, the Fatty has the benefits you&#39;re looking for.More tractable power, improved throttle control.Provides power gains throughout entire power band.Carbon steel with a nickel-plated finish for maximum durability.FMF R Not intended for street use.Detailed Specifications: Weight: 5.5 pounds.