FMF 4.1 RCT Muffler System (2020-2021 Honda CRF250R)

The 2020-2021 Honda CRF250R chassis is one of the most fun to ride in the 250 class, with its easy to corner nature as well as a great suspension package. However, Honda focused a lot of their engine R&D on peak horsepower and not torque, which to me the CRF250R lacks the most of. When riding the Honda back to back with other models in its class, it’s obvious that the Honda needs a little help/pulling power out of corners. I went to FMF to see if they had what I needed in a muffler package and came away with these thoughts for you to digest. 

Let’s address the elephant in the room first. Can I even get one at this time? Sadly, most likely not. COVID has done a number on a bunch of stock with anything related to dirt bikes! This is not just with FMF, Pro Circuit, Yoshimura, etc., as this is happening with a lot of other key parts to our industry as well. The reasons go from not enough workers/employees to keep up with the demand to not enough material to build the product. This pandemic affects eery business and our industry is no different. This is a good thing and bad thing. Our industry seems to be booming, which is great, but us die hard moto dudes have to wait for months to get a damn muffler! That sucks and I get, but you need to breathe! FMF plans to have Honda mufflers back in stock in March, so if you have placed an order for one of these or any other Honda FMF muffler system for that matter, look towards the middle of March for delivery. Give these muffler companies some time and patience as we all are dealing with some sort of back log because of the pandemic. Plus I have heard that some people just simply don’t want to work at this time!

I like the fact that even though there are two headpipes and two mufflers it still didn’t take that long to install. The headpipes go on super easy and the mufflers slide into the slip fit joints with ease, yet are tight enough so the joints don’t wear out too soon. I have over 20 hours on the FMF 4.1 RCT mufflers and the slip fit joints are great, which is rare for titanium slip fit joints. Another added feature is that you will be losing close to two pounds off of your CRF250, which can also aid in helping the Honda’s chassis even more.

So let’s start off with a couple things I didn’t like from the FMF 4.1 RCT system. The pitch/sound of the FMF 4.1 RCT mufflers are LOUD! The sound is deep and throaty but it is loud compared to other aftermarket mufflers! I didn’t run the quiet inserts, but I plan on trying these to see what it does to power and sound. Once I rode with the system for an hour or so the sound actually improved/dampened as the packing inside expanded. So don’t completely freak out when you first start it up. The second thing that you must pay attention to is that the headpipe springs can break and that could cause your headpipes to pop away from the exhaust ports of the cylinder head. I had this happen two times over the course of almost 22 hours so make sure you keep new springs on the headpipes. I learned if you keep new springs on, the headpipes remain on and don’t give you any issues. I would go no more than 8-10 hours on a set of pipe springs. 

Now with everything I did like about this muffler system: The power delivery is great and FMF made more power where the CRF250R needed it! The Honda needs bottom end and this is the only dual muffler system that has given me more grunt/low end out of corners! THANK YOU! The Honda CRF250R comes out of ruts/deep soil stronger and pulls harder through the mid range. Second and third gear recovery is improved as well as low-mid RPM response. The FMF 4.1 RCT muffler system makes the Honda feel more exciting and lighter around the track, which helped me improve my cornering. Top end/over-rev is as good as the stock mufflers and to me that is just fine because now I am able to short shift the CRF250R more than I could with the stock system. I am running a 13/49 gearing spec with the FMF 4.1 RCT system and that gives me more options with third gear through corners. With the stock muffler and 13/48 gearing, using third gear wasn’t even a thought in my head.

The FMF system will set you back $1500.00 which is my last gripe of this article! Holy crap that is expensive, but at least I know if I have my mind made up on spending my money on an aftermarket muffler system, I know I am getting something out of it with the power increase.  You can visit rockymountainatvmc.com or fmfracing.com to get yourself on the list for the next production run. 

FMF Factory Fatty Pipe/Shorty Silencer (2020 KTM 125SX)

Since the delivery of our KTM 125 SX, my son Aden has been riding it non stop. He also has been barking in my ear about getting a pipe and silencer so it “sounds cool”. While I am usually reluctant to add parts to my kid’s bike for the sake of just doing it, I thought this could be a good way to test a pipe and silencer to see if it actually helps the Austrian two stroke power plant. After I discussed “the conditions” to my kid, I called upon Lil D and the boys at FMF to send me a Factory Fatty pipe and Shorty silencer to try. 

What were Aden’s “conditions”? The conditions were that he had to install the FMF products and help me write this test. I took it upon myself to ride the 2020 KTM 125 SX in stock form as well as with the FMF Factory Fatty/Shorty combo at couple tracks. The installation was fairly painless for my 13 year old. He learned how to use a spring puller for the first time as well as how to push the rubber grommets through the silencer mounting points without stabbing himself with a flat blade screwdriver. Once he got the FMF pipe/silencer installed he of course had to start his bike and see how it sounded and I will have to admit, it sounds pretty bad ass. The pitch of the KTM 125 SX with the FMF pipe/silencer is more of a crisp/barking sound rather than a richer/raspy sound that the stock pipe/silencer comes with. Ok, now that we smoked out the garage and pissed mom off, we loaded up the bike and went riding! 

I went back and forth with the stock set up as well as the FMF a couple times at a few different tracks and I will say that the FMF Factory Fatty pipe/Shorty silencer combo did help throttle response as well as low end grunt. Coming out of corners (with the FMF Fatty/Shorty) the KTM 125 SX has a little more acceleration pull on corner exits and could be shifted a little earlier without falling off. The mid range pull was also longer and overall crispness of the mid range seemed improved. The FMF Fatty/Shorty seemed to lean out the bottom to mid range (in a good way) and made the KTM feel more playful around the track. RPM response was improved throughout the power and the throttle felt more connected to the rear wheel. 

The top end pulling power/over-rev was slightly shorter than the stock set up so I wanted to play with jetting to see if I could get some of that back. I went back and forth on a few different main jets as well as needle jets, but came back to this set up below: 

Jetting Specs:

Needle position: 3rd position from top

Jet needle: 6BFY43‑71 

Main Jet: 520 (500 Stock)

Idling Jet: 35 

Choke nozzle: 80

Needle Jet: S‑7

Idle Air Adjusting Screw: 1.5 turns out/open

With this jetting the KTM 125 SX pulled longer up top and gave Aden/I more over-rev in 2nd-3rd gears. To me these two gears are the most important for Aden as he learns how to improve his corner speed as well as technique. Sometimes Aden will leave it in second or third gear too long (instead of shifting) and having this jetting allows the KTM 125 SX to pull a little longer. This jetting was good for sea level up to 3500ft. Anything higher than 3500 feet elevation and I would go back up to the 2nd needle position. 

Overall, there is some performance gains to be had with the FMF Factory Fatty/Shorty Silencer. Aden has put over 14 hours on the system and the silencer still sounds good and not blown out. He did manage to put a small ding in the bottom of his pipe and that made him mad, but he’s ok with it after he took some WD-40 and Scotch Brite to the thing! Proud dad moment! The Fatty is $249.99 and the Shorty costs $134.99. A lot les expensive than a four-stroke system! 

Below is Aden’s opinion of the FMF and stock pipe/silencer. I wanted to let him have free range on what to talk about, so he can try to get better at communicating his thoughts into a testing format. During the course of this test I never shared my thoughts about the FMF Fatty/Shorty for confidential purposes. His opinion is unedited, but I did clean up a few grammatical errors for the sake of reading. After reading his opinion, I couldn't help but write down my thoughts about his opinion. It seemed too good not to share with you all. Enjoy! 

Aden Keefer Opinion: 

The differences between the stock pipe vs the FMF Fatty/Shorty pipe is that the FMF pipe hits stronger coming out of corners, but on the other hand the stock pipe is a little bit more linear coming out of corners. The stock pipe takes a while for the power to kick in which was ok on hard pack desert tracks that I rode. I did like the FMF pipe more because it was aggressive and you can put the bike anywhere knowing that it’s gonna have the little extra power. The one reason I do like the stock pipe is that since it’s more of a longer silencer I can control it better when I get tired because it’s not so aggressive. Don't get me wrong though! I think the FMF pipe and silencer is one of the best pipes out there. Not does it only make your KTM 125 SX faster, it makes it look super cool and it sounds way better than the stock pipe. I also noticed when we put VP C12 in the stock pipe/silencer it made it run aggressive, but when we also tried out VP C12 with the FMF pipe/silencer it ran like a race bike. It made it so fast that I was pulling all the 450’s going up Mt.St.Helens at Glen Helen. I also think cleaning the FMF pipe/silencer is rewarding. My dad loves to vacuum because he said he can see his progress with his work. I like cleaning my FMF pipe and silencer because I can see my progress as I scrub it with an SOS pad. So to wrap this up, I think that the FMF pipe and silencer is the best pipe out there for any 125's out there.

Dad’s Thoughts About Aden’s Opinion: 

-I appreciate some of these testing comments and at least it shows that he is listening to me a little. So you’re saying there’s a chance! Hallelujah!  

-I like that he could feel that the FMF Fatty/Shorty had more bottom end. That shows me that any kid could install this product and feel the difference. 

-It’s funny that he recognizes how the KTM works on different terrain and can appreciate a smoother power at times. I am glad he’s not a balls out rider! Safety first!

-Pulling 450’s up MT. Saint Helens? Eaaaaaaasy there tiger!

-Of course when I was his age I also thought something that was aftermarket was way cooler! Why? Because it wasn't stock! Duh! After reading his opinion it seems that he’s into the styling of the “Raw Fatty look”. Me too, Aden, me too! 

-Here we go with the C12 talk again! That is all this kid was talking about for a few weeks! “Dad, let’s get some C-12”! “Dad, let’s get some C-12”! I broke down and got some. The C12 did make the KTM’s pulling power stronger, but also leaned it out enough to warrant the jetting change. However, the jetting change that worked with the VP C-12 also worked with pump gas too. Don’t be scared to run that jetting with either fuel. Aden wanted it because of the smell! Mom’s still mad because her kitchen smells of C12 and Maxima Formula K2. Sorry, babe! Not really, because our house smells like a race shop now! :)

-Aden coming in hot with the vacuum reference! Wow! My secret is out now. Great!

-Good job Aden. We have some work to do, but good job son! Love, Dad!