23’ YZ450 Gearing Question

After reading through the 2023 YZ450 thread I talked my pops into trying 14/52. He raced with it for the first time a few weeks ago and said he couldn’t believe how much it changed how the bike handled, more free was what he was saying.

The 14/53 is really close to the stock ratio 13/49 of 3.77/1. The 14/53 is 3.78/1, so really close. I think the upside is it is supposed to make the suspension work a little better because of how it loads it. The 14/52 is a little taller gearing at 3.71/1 ratio.

This engine has so much grunt it's begging for taller gearing. Ride a FX with the wide ratio 5 speed and you'll be surprised how awesome it is. I just finished building my spare 450fx and I put a 14/50 on it to see if it stretched out 2nd some more, the fx 1st and 2nd are actually lower geared than the f, and so far I'm digging it. Everyone wants to buy aftermarket ECU 's to tame the power, when really you can smooth/stretch it out with gearing really easily and cheaply. While you're at it throw a 2 link longer chain on it and move the rear wheel back ~3/4 of an inch, feels so good! Adds stability and still turns really well! 

I was wondering about the 14/53 gearing too. Couldn’t find a definitive answer if the 53t causes accelerated wear on the lower chain guide due to the extra diameter. 

Unless your a fast pro or super heavy that bike will pull 14/52 gearing and you’d never know the difference. I ran that gearing on my 24 and was using the “smooth linear” map with traction control on high. The bike was still stupid fast. 

My son also had the same bike. He is local pro speed and he also preferred that set up over stock. Said it calmed the bike down a little on power delivery making it easier to ride and also helped the chassis. 

Could someone explain the physics for why a nearly identical ratio with different sprocket sizes would impact the chassis or suspension? 

I wish I could explain it and understand it better myself. I can see how it would pull or torque the swingarm at a slightly different angle because when you accelerate it is pulling up on the arm. I may not be able to feel it like a test rider like Keefer would, but I have read in several places how it affects suspension movement. I remember the ATK that had the two sprockets mounted above and below the front of the swingarm to lessen the torque effect on suspension, so there must be something to it.

I also fail to see how it helps if you use a gearing that is nearly identical in overall ratio. I played around with this excel file a while back, and it seems if the gearing ratio is kept rather constant (say +1 front and +2 or +3 in the back), the antisquat value is almost identical to whatever oem setup you have. People seem to notice the difference though, I’d imagine there has to be something to it, and am genuinely curious as well.  Maybe another geometric trait I’m not thinking of?

Link below to the calculator:
https://www.datamc.org/downloads/motorcycle-anti-squat-calculator/
 

Has anyone tried 14/53 vs 13/49 with the axle position to the rear?  

Seems like it could just be axle position creating a "more free feeling"

 

The larger front basically gives the swingarm more movement with less binding allowing the shock to move through stroke smoother.  I have tried 14-50,51 and 52.  My preference is stock, 13-49 or 48.  48 is great for tracks with wider turns.   14-50, I could stay in 2nd longer and never shifted into 4th at most tracks.  With the 14 front, I felt that the Linear power map was better compared to the Linear Torque that I use with the 13 front.

Under what scenario does the chain bind?

Larger sprockets mean larger radius, so easier for the chain to go around. The larger sprockets also mean the chain is dragging on the swingarm less, especially at the pivot point, this was a big factory racing trick back in the 2-stroke days. 

I ran 14/53 on my 21 because of what keefer was talking about and it was too snappy down low for me. Im a long time 450 rider and it had me questioning if I could still handle a 450 anymore. I switched back to stock gearing and life was good again. I really struggled on the 450 with the 14/53 setup when I would ride it back to back with my 350, because of how much more aggressive you are when riding the 350... especially when you were coming out of corners where you're getting on the throttle much earlier with the 350 vs pulling a taller gear out of the corner with a 450.

I tried 14/53 gearing, was able to get my axle position the same...............didn't notice any difference compared to the 13/49.  

Only 1 ride in; I'll keep using it until I need new sprockets, then switch back to 13/49 to see if I notice a difference going back.


 

I noticed a small change running 14/52. Got axle position to roughly same position so any change is RPM or chain torque related.  

14/53 would be good too especially on tighter tracks, but at 14/52 is already pretty close to chain guide. 53 would be really tight. Can’t see running 54 without it running a bunch. 

I’d just buy a super cheap 53 and try it.