FLASHBACK! INNERMOST SECRETS OF JOSH MOSIMAN'S PALA NATIONAL YZ450F - Motocross Action Magazine

The Yamaha YZ450F won our “2023 MXA 450 Shootout,” and we raced it at the 2023 AMA National Motocross season opener to add more test time to the YZ450F.

BY JOSH MOSIMAN

Q: WHY DID I CHOOSE THE YAMAHA YZ450F FOR THE PALA NATIONAL?

A: After my first test session on the 2023 Yamaha YZ450F at the Star Racing Yamaha facility in Cairo, Georgia, my first words to the Yamaha mechanics were that I wanted to race the bike at the 2023 AMA 450 Nationals. Then, after riding, racing, and testing the 2023 YZ450F back home in California, I discovered it wasn’t the flawless bike that it was on Star Yamaha’s perfectly groomed test track, but it was still the best bike of the bunch for me. In back-to-back, stock-to-stock tests, I was consistently the same speed or a little faster on the YZ450F than I was on the 2023 KTM 450SXF that I had raced at the 2022 AMA Pala National.

The custom-engraved MXA logo makes us like these Luxon Gen 3 clamps even more special.

Based on feel, I would have thought I was faster on the KTM, but the MyPitBoard lap-time-recording GPS bar pad recorded my lap times each time I rode, and that settled the score. This particular test was conducted on a rough and rutted day at Glen Helen. The freakish rainy season had left a lot of sand on the track and great moisture in the dirt. The conditions were great for testing. I went back and forth for hours to fact-check myself, and my times on the Yamaha continued to surprise me.

The 2023 Yamaha YZ450F was my choice for MXA’s “450 Shootout” winner, and after we combined the opinions of all of MXA’s test riders, it unanimously won the “MXA 450 Bike of the Year” title. So, of course, I was excited to race this bike at the first 2023 National and was looking forward to seeing how much better it could be once it was set up for me.

Guts Racing is generous with the grip.

Q: HOW WAS THE BIKE IN STOCK FORM?

A: Luckily, we don’t stop testing after the first couple rides, we test constantly by racing our test bikes weekly (thanks to the hard work of our regular test crew). I raced the stock YZ450F quite a few times, even after our 450 shootout was complete. The suspension was too soft for me, but I can’t knock Yamaha for that. One big complaint I had was that the front end was very twitchy. The YZ450F went from 2023’s big, wide, heavy and stable machine that wasn’t so easy to initiate turns with to a skinny, nimble, lighter, and twitchy machine that loved to be whipped, scrubbed, and railed. It was also not stable in high-speed chop. Many longtime Yamaha lovers hated the new chassis because it oversteered at turn-in, and it exhibited head-shake at speed. Not to mention, it wheelied every time you turned the throttle on. But, if you are coming from any other brand onto the Yamaha, or if you had problems turning last year’s bike and never got it figured out, then you’ll like the 2023 model.

The Maxxis SM scoop tire.

Before switching out the triple clamps or sending the suspension off to be revalved, I raced the stock YZ450F, I tightened up the poor man’s steering stabilizer (steering stem nut), slid the forks down into the stock triple clamps until they were flush with the top triple clamps, and set the race sag to 107mm. This shade-tree mechanic’s setup helped me beat some good riders and win some Pro races at Glen Helen, but I knew the bike could be better with help from the aftermarket.

The Raptor 2 front number plate is a new product from Acerbis.

Q: WHAT DID I DO TO THE YAMAHA CHASSIS?

A:Here’s a list of the notable changes I made to the bike.

(1) Suspension. First on my to-do list was to get some A-kit suspension from Kayaba. Enzo Racing works closely with Kayaba, and they were nice enough to set up my YZ450F for the Pala National. After two test days on the A-kit suspension for the YZ450F—one at Perris and one at Glen Helen—I decided the forks needed more hold-up. I rode Perris a second time on Friday morning, eight days away from the National, to double-check that my sense that the suspension had been too soft on Thursday at Glen Helen was, in fact, true. Then, I drove the still-dirty bike to Enzo, and they went stiffer on the valving for me that afternoon. I rode it the next day (Saturday) at Lake Elsinore, and it was good! The real test would come on race day, but the forks were noticeably stiffer, and that’s what I was hoping for.

The big goal on the 2023 YZ450F was to find a balance between high-speed stability and accurate cornering.

(2) Triple clamps. Luxon MX has been working on its Gen 3 Yamaha triple clamps, and they came out just in time for the first National of the year. I tested two versions—the Gen 3 and the Gen 3 Pro. It’s a household joke between my wife and I that if there’s a regular version and a Pro version, I always choose the one with “Pro” in the name; however, my real reason for choosing the Luxon Gen 3 Pro clamps was that they offered adjustable offset. The Gen 3 standard clamps are more affordable, while the Gen 3 Pro clamps spare no expense on material, design or finish. Plus, they come with eccentric inserts in the top clamp and eccentric steering stems, giving these clamps the ability to switch between four offsets. The clamps can be set to 21mm, 22mm (stock), 23mm and 24mm offsets.

I got the clamps a little over one week before the Pala National. Luxon’s Billy Wight came to the track to set the clamps to 24mm of offset to increase straight-line stability, which I could afford to do on the YZ450F chassis because its oversteer on corner entrance would be tamed a little bit by the larger offset numbers. I installed Luxon’s 26mm bar mounts, which are 5mm taller than stock, and I turned them so that they were 2.5mm further forward than stock. Did I mention Billy custom-engraved the MXA logo into the clamps? I installed ODI’s Podium Flight handlebars onto the Luxon clamps with ODI’s Emig Pro V2 lock-on grips.

(3) Footpeg mounts. Works Connection first came out with lowered footpeg mounts that were made from titanium, but they were too expensive for the amount of weight savings they provided. So, they quickly added aluminum lowering mounts to their inventory, and that’s what I used on my 2023 YZ450F. The mounts were originally made for the 2022 YZ450F, but they work on the new bike, too. Thankfully, Yamaha lowered the stock pegs on the 2023 YZ450F, for the most part fixing the “cramped” feeling we disliked; however, I’m a taller rider and still wanted the pegs to be lower. Plus, it’s easy to find for your boot to end up on top of the stocvket mounting bracket instead of on the footpeg.

The Works Connection mounts fixed this problem. The mounts are the same for the 2022 and 2023 bikes, but the geometry is different for the ’22 and ’23 models. When used on the 2022 bike, the footpegs are 7mm lower and 5mm farther back; however, on the 2023 YZ450F, they are only 4mm lower. Important note: I borrowed the footpegs off of our 2023 YZ250F to work with these mounts, but I could have could have used any aftermarket pegs.

Throttle Syndicate put the icing on the cake with this YZ450F race bike by dialing us in with custom graphics.

(4) Grip. Of course, I added a Guts Racing RJ Wing seat cover with the hump on it to help me hold onto the YZ450F. If any bike needs more grip from the seat and a huno, it is the wheelie-prone 2023 YZ450F. Just to be double sure, I added grip tape on the frame. After I borrowed some grip tape from Pro Circuit Kawasaki mechanic Jacob Martin, he gave me a tip on which grip tape to buy. He told me to get Black Diamond Skateboard Longboard grip tape. I bought a 60-foot roll of clear tape on Amazon for $64.95. I made templates out of cardboard and used it to cut out multiple sets of gripper frame tape. I grip pretty hard with my legs, so my trusty National mechanic Josh Fout had to add new tape each time I hit the track.

(5) Starting device. We positioned the Works Connection Pro Launch starting device down at 130mm, but I realized after Hangtown that we needed it lower for one-to-one traction off the new metal starting grates.

(6) Tires. Maxxis introduced the all-new Maxxis MXSI “soft intermediate” terrain and MXIH “intermediate hard” terrain tires just in time for the 450 Nationals. With our heavy schedule of testing and typing, I didn’t have much time to try the tires before Pala, and I actually learned some valuable lessons on the Monday after racing the Pala National. I was running the MXSI tires with 13 psi in the front and 12.5 psi in the rear, but, while riding in some sticky conditions at Perris Raceway, I realized the front tire was grabbing the edges too much for me. I bumped up the pressure to 14 psi in the front and 13.5 in the rear, and I felt like a new man! The extra air helped me drive through the rough and sticky chop with ease, rather than my tire deflecting off each one. I also used a Maxxis SM scoop tire for the muddy first qualifying session at Pala, and it was amazing. They always rip and water the National tracks too deep, so the scoop tire was a great choice for the first qualifying session.

(7) Aesthetics. Acerbis helped me freshen up the YZ450F with a complete set of plastics, and the new Acerbis Raptor 2 front number plate featured a wraparound triple clamp guard, which I appreciated very much because it kept the Luxon triple clamps away from the roost. Throttle Syndicate made the sweet MXA graphics, highlighting all of our supporters of this build, and put Josh Fout’s name (fellow MXA test rider and my mechanic) on the rear fender.

Lesson learned, don’t forget to transfer the spring seat from the stock pressure plate to the new Hinson plate.

Q: WHAT DID I DO TO THE ENGINE?

A: The 2023 Yamaha YZ450F was already plenty powerful. Instead of looking for more power, I just wanted to make it ridable and reliable with the parts I added on.

(1) Mapping. Jamie Ellis of Twisted Development used the GYTR Power Tuner app to create a map that smoothed out the initial hit off the bottom.

(2) Exhaust. I used an FMF Factory 4.1 titanium exhaust system with its cool-looking carbon fiber end cap on the muffler. The FMF exhaust didn’t add excessive amounts of power, but it helped smooth out the initial hit while keeping a broad and usable range of power.

(3) Bypass. New on the YZ450F for 2023 is the engine breather hose. Instead of the engine breather hose venting straight out to the bottom of the frame’s cradle, the YZ450F recycles the hot, oily, blow-by air from the combustion chamber back into the intake to be burnt off for emission’s sake. This isn’t required on motocross models, but Yamaha did it anyway. I haven’t noticed any issues or weird bogs because of it, but I had a bypass installed out of precaution. Honda has a similar system, and Twisted Development knows how to bypass and reroute the overflow hose so that the hot and oily blow-by vents straight out of the bottom of the bike.

Josh used the FMF Factory 4.1 titanium exhaust system.

(4) Clutch. Almost from day one, the YZ450F clutch was the weak point of the new Yamaha YZ450F. Although Yamaha copied KTM by replacing the six coil springs with a Belleville washer spring and copied KTM a second time by replacing the aluminum basket with a steel basket that had the primary gear machined into it, the Yamaha clutch didn’t have a positive feel and it faded very quickly. Every test riders mentioned that the clutch went soft early in races. We think that the Belleville washer clutch spring isn’t stiff enough. My biggest complaint was that I couldn’t tell where I was when using the clutch, because the engagement point changed as the clutch heated up.

To increase durability, Hinson made a new inner hub and pressure plate that flowed more oil into and out of the clutch, keeping it cooler and helping the plates last longer. I installed the clutch on Tuesday before the race, and luckily, I had press day to test it out, because I forgot to switch over the steel spring seat from the stock pressure plate to the Hinson one. Rookie mistake. It wouldn’t allow the clutch to engage properly, giving me serious slippage on the track. Thankfully, we figured it out before race day when Ron Hinson stopped by our pit to check on us, so I was able to throw in the proper spring seat for the National.

(5) Oil. Another essential piece to the clutch puzzle is keeping fresh oil in your bike. The oil is the blood of your engine, and, as your clutch is used, particles from the fiber plates mix into the oil, which hinders the engagement of the clutch. I used Red Line Oil’s 10W-40 blend, and we made sure to change the oil and the clutch plates after my escapade during the press riding session so that it was fresh for racing on Saturday.

The Works Connection footpeg mounts drop the pegs an extra 4mm.

Q: HOW DID THE YZ450F WORK IN RACE CONDITIONS?

A: In the end, I was happy with how the new Yamaha YZ450F worked at the Pala National, and I couldn’t expect much more with so little time for prepping the bike. Straight off the showroom floor, the rider triangle is new and improved on this bike, and the slightly lower Works Connection footpeg mounts made it even better. The new, taller and rounder stock seat foam doesn’t make for a rider-friendly seat, but the extra foam on the edges of the Guts Racing RJ Wing seat made it more comfortable while adding extra grip for my legs.

The engine is still my favorite aspect of the 2023 Yamaha YZ450F. Second gear pulls so long that it almost feels like third gear when rolling into the power at corner exit. This chassis is far nimbler than the previous one, and I had no problems turning it at Pala. As for straight-line stability, the Enzo suspension, along with the 24mm offset clamps, handled the Pala track well. I did have issues with the YZ450 airbox. The rubber strap that attaches to the air filter catch doesn’t pull the filter down, instead it pulls it forward. This allowed dirt to migrate under the upper front right side of the air filter. In the end, I switched to the latest Twin-Air filter which not only comes with KTM-style rubber grommets (front and rear), but an aluminum L-bracket to hold the front of the air filter down.

I would have loved to have been able to race the YZ450F at the second AMA 450 National at Hangtown, but I had vowed to race a different bike at every AMA National I raced, and when Pala was over, I was back at the track testing the 2023-1/2 GasGas MC450F Factory Edition in the few days before I had to leave for Hangtown.

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