Tested: FMF Factory Fatty Pipe and Shorty Silencer 4

For over 50 years the Flying Machine Factory has been a staple of the motocross community. Donny Emler Sr. started building exhaust in his garage in 1973 and to this day FMF builds some of the best performing, looking, and sounding after market exhaust on the market. When you see the iconic red and yellow oval shaped logo, one can't help but think of the long history of building power and winning championships. FMF sent us one of their Factory Fatty pipes and a Shorty silencer for our 2022 Yamaha YZ250 to see what we thought.

FMF Factory Fatty Pipe 

• Reminiscent of the Works or "Cone" pipes once used by Factory teams
• Lighter 20 gauge steel for the body
• 19 gauge used on the header portion
• Hand pounded seams for smooth flow transitions
• O rings included 
• 5 lbs
• MSRP $299.99

FMF Shorty Silencer

• Shorter inner core length
• Aluminum canister
• 2.2 lbs
• MSRP $179.99

First Impressions

When I unboxed the FMF exhaust system I pulled the Factory Fatty pipe out of the bag first. Visually, it's a work of art. The Factory Fatty pipe looks similar to the old factory cone pipes with the bare metal being left exposed and the weld lines. It doesn't look 'pretty' like it's nickel plated brothers. It looks 'mean' as if it might punch you in the face if you say something disparaging. Now, if you like 'pretty' things on your bike, have no fear. The Shorty silencer fits the bill. The silencer adds the bling look with it's shiny aluminum canister and FMF logo. I had to install these parts immediately.

Installation

Installation of an exhaust system is fairly routine and easy. Obviously, don't change these parts shortly after running the bike because the existing ones will be hot. The only remotely difficult thing was removing the grommets from the original silencer and installing them in the FMF one. I used a flat tipped punt and pushed them through. I found that to be efficient and the punch didn't poke a hole in the rubber. Once the grommets were in, I bolted the new system up, hooked the muffler springs, and made sure it was all tight. Time to ride.

On the Track

I'll start by saying the power of the '22 Yamaha YZ250 in stock form was impressive. I've been on four-strokes for years and like being able to 'lug' the bike through corners. Rev'ing a two-stroke isn't something I have done in a long time and I loved how the YZ could almost be ridden like a four-stroke. The power came on smooth with a very linear power curve. I didn't feel that moment when the power band would snap awake around half throttle and try to get away from me. Once I installed the FMF Factory Fatty pipe and Shorty silencer that changed. The Shorty silencer is designed to give you maximum bottom and mid-range power as is the Fatty pipe. It most definitely woke it up even more in those areas. I felt a significant increase in power in the bottom end when coming out of corners. As soon as I exited a corner in second gear and cracked the throttle the bike snapped awake and I could shift to third a bit sooner. At mid to full throttle, it was a fire breather. I mostly kept it in second and third gear and the bike simply felt snappier. The front end would start to come off the ground mid-throttle as I rolled through the power curve. At the high end of the power it felt as though the power didn't fall off as soon, so you could shift later. 

Durability

Listen, it's an exhaust system. If you have a big crash or some out-of-contol goon t-bones you, it probably will get damaged. Baring those situations, it's FMF, so it will last. Depending on how much you ride, the time will come when you need to re-pack the silencer but FMF sells packing material. The Factory version of the Fatty pipe does need a little extra care due to it not being coated. I simply dried it after washing and if I saw any signs of rust I would take an SOS pad or a Scotch Brite and gently scrub it off. 

Final Thoughts

The FMF Factory Fatty pipe and Shorty silencer add a performance upgrade in most areas of the power. The question is, do you want that extra power in those areas? For me, I actually liked the more linear, mellow power delivery of the stock system. I always mention that I'm an average vet rider and I can not ride the bikes to their full potential. There were moments with the FMF installed where it was a handful to hold onto. If you're looking for more bottom-end and mid-range power then you will be happy with this system. In my opinion it would most be beneficial if riding supercross, arenacross, or tighter conditions. Also, if you're a more advanced rider you would most likely appreciate the performance benefits of this system. It also looks amazing and sounds incredible. The sound of a finely tuned two-stroke screaming around a track can not be matched. My final thought is to say that the FMF pipe and silencer is an upgrade, but I it wasn't an upgrade I absolutely needed or could even use to it's potential. That being said, if you're looking to get a little more out of your two-stroke, the Fatty pipe and Shorty silencer would be a could purchase.