Not everyone wants to “add” parts to their new dirt bikes, which is fine, but for those that must tinker, we put together a “Top 5” must haves that we would recommend. We will be doing these “Top 5” articles with all of the new 450F/250F machines and will be splitting the information up between pulpmx.com and keeferinctesting.com. These mods are recommended, by us, through countless hours of testing. If you don’t find a specific aftermarket company that you prefer in this article, don't fret, email me at kris@keeferinctesting.com and we can talk it out like adults should. Again, we will not push something on you unless we know it works. These mods that are in this article simply work for this specific machine.
1. Fire Power Battery: The stock Yamaha YZ450F battery is a problem. It doesn't like to start in gear and if you do try to start it in gear for too long the battery will drain quickly. I have had countless emails sent to me about Yamaha batteries and the only thing I can tell you guys is go with an aftermarket lithium ion battery. I have been using Fire Power batteries in my Yamaha’s and they all have been great. Not to mention that they are lighter than stock, so losing some weight doesn't hurt. For around $125.00, it’s a fairly inexpensive way to prevent you from being stranded at the moto track with a dead battery.
2. GUTS RACING Stiff Seat Foam And Gripper Seat Cover: Yes, we know Yamaha made some stiffer changes to the foam for 2019, but once the foam breaks down a little we are back in 2018 all over again and hitting the fuel tank when slamming into ruts. Going to a GUTS stiffer foam does wonders from smacking your butt bone into the fuel cell that lies underneath you. Does be scared off by the word “stiff” as the GUTS foam is stiffer, but not so bad where you will be getting monkey butt. I go with the standard stiff foam and not the phantom foam as I like the feel of the standard stiff foam more. While you’re at it go with a gripper seat cover and prevent your rear end from sliding under acceleration. The stock Yamaha seat is slippery after about 20 hours and will not hold you in place from that explosive Yamaha 450 power.
3. Heavy Duty Chain: Like most stock chains the Yamaha chain will stretch and be smoked before the 8 hour mark, so get a good high quality heavy duty D.I.D. 520 ERT2 Gold chain. If you don’t mind the weight and the drag of an o-ring chain that is also a great choice.
4. FMF 4.1 Full Muffler System: I am not going to sit here and tell you that you NEED an aftermarket muffler for the 2019 YZ450F, because you don’t. The stock muffler is so good on this bike that it’s not something you will need right away. However, I know most of you have A.D.D. when it comes to putting shit on your bike, so I will recommend a muffler that I had some help in testing recently. I helped George at FMF come up with a different setting inside the muffler (or core) of this system to create some more back pressure, in order to keep the bottom end that the stock system has. The FMF 4.1 system knocks off almost two full pounds of weight, retains the stock bottom end power, increases the mid range and top end, and will only lose minimal over-rev. I have tried a ton of aftermarket mufflers for the YZ450F and all of them lose bottom end. Not this one…
5. Front Brake: The Yamaha front brake is not the best of the bunch when it comes to stopping power, but there is a modification you can do to make it insanely good (besides just throwing an oversize rotor on). If you want increased stopping power without the grabby feel, purchase an older Yamaha caliper (that used a bigger piston/part number shown) and an older KTM Brembo master cylinder (part number shown) while using your current 2019 YZ450F brake line and feel the magic coming into corners. You will be able to brake later and modulate the front brake better in shallow ruts than you can with the current front brake. This set up is also much more linear and less grabby than just throwing on an oversize front rotor as well. Just make sure to purchase the stock KTM banjo bolts and use your current 2019 YZ450F front brake carrier along with the current brake pad clip..