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Yamaha changed the linkage ratio for 2025 on the YZ450F. Yamaha was looking to keep the rear up so basically the whole curve of the 2025 linkage ratio is stiffer and that is why Yamaha went down on their spring to a 5.6 N/m from a 5.8N/m spring on the 23/24 models. When Mark Johnson at REP introduced his linkage to me in 2024, I was ecstatic to try it because I felt the ratio was too soft on the 23/24 models and that meant I had to run a stiffer rear spring rate in order to keep my rear end feeling up when accelerating out of corners. I also felt that the end stroke of the Yamaha felt “empty” at times when under heavy loads. Getting a shock dialed in on my 2024 Yamaha was tough with the stock linkage because the curve was simply too soft initially.
I went out for several days to test with Mark and crew at REP in order to try and dial in the REP linkage for the YZ450F. When we did get it dialed in, I had way more rear end traction and more comfort out of the rear end of my YZ that wasn’t there with the stock linkage. Then we got word that Yamaha changed their linkage for 2025 and I was like, well does REP have to start over? Luckily they didn’t and the REP linkage works well on the 2025 machine too! Yamaha went stiffer with the curve on the 2025 (compared to the 2024) but I feel like the 2025 lost a little comfort on acceleration with the stiffer linkage. I just felt like the rear was too tough on throttle and when off throttle overpowered the fork a bit too much.
I like to call the REP linkage “the in between” linkage ratio. The REP linkage ratio start close to the 2024 (a little stiffer) and ends near the 2025 curve, yet a little softer. The good news is that you also DO NOT have to go to an optional spring if you’re on the 23/24 YZ450F models as the stock spring will work. If you’re on the 2025 YZ and looking for a little more comfort from the rear end on throttle as well as slightly less toughness near the end of the stroke, the REP linkage delivers. If you’re on the 2025 YZ450F, you may have to go back up a spring rate because like we mentioned, Yamaha went down to a 5.6N/m spring for their tougher linkage.
Overall, even if you’re just running stock suspension on the Yamaha, this REP linkage is a good mod for increased rear end traction and more comfort across acceleration chop. If you’re a 23/24 YZ450F owner, this REP linkage helps keep the rear end up more under acceleration so the Yamaha doesn’t squat as much. When the Yamaha stays up in the stroke under acceleration it helps with traction and doesn’t feel as harsh on acceleration bumps.
If you’re on a 2025 YZ450F the REP linkage will help with more compliance across chop and just give the rider more comfort on bump touch. The rear end will not overpower the fork as much and ride attitude is better off throttle. For $450.00 the REP linkage is a good buy for the Yamaha rider that needs a little more comfort from the rear of his YZ450F. We are normally running a sag reading of 104-105mm with the REP linkage. Make sure to check the sag once you bolt on linkage as it can/will change. Another bonus is that the REP linkage comes installed with OEM bearings ready for use (once greased of course). The catch is that you will have to call or email them to order. It is not up on their website yet. repsuspension.com is the place.
