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11/1/2018
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Reidsville, NC
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Cole_Crawford
3/22/2021 4:58am
3/22/2021 4:58am
I've read allot of posts about putting the 2009 yz450 swing arm on the yz250 two stroke. My question is what combination of linkage or dog bone people are using. Maybe the difference in different lengths and which performed best.
09 yzf swingarm uses a 142mm linkage
A 143 or 143.5 is what a lot of the aftermarket likes as it drops the rear just a bit .
Your 06+ yz250 uses a 146mm so way to big.
I haven’t been able to verify the exact mm differences between them but IIRC there are slight ones between the various models.
The Shop
For the YZ conversion the 143.5mm YPA10450 Pro Circuit pull arm sets the rear end very close to the stock YZ spec. There may be other companies that make a 143.5mm arm, but I'm not aware of them.
Pro Circuit says the YZ250F 2009 and 2014-2018 and YZ450F 2010-2020 is 142.0 mm and the stock YZ125/YZ250 2006-2021 is 145mm.
https://youtu.be/MuZoVZhxNjk
🤣
Sort of like the F bar clamp centers. I've seen some say 102.5mm and others saying 103mm.
With the pull arms I measured the pivot to axle dimension and fender bolt to axle before I took the stock parts off. Then with the F parts installed I set the pivot to axle distance the same as it was with the stock parts. Then I started trying different arms and measuring the fender bolt hole to axle again. The OE arms made big differences to where the stock YZ was. It's like a couple of inches difference between the YZ and F arms. I tested both and did not like either one, even after moving the forks in the clamps to try and get the balance right. I'd say the YZ arm with the forks slid way up in the clamp is the better of the two options. The bike sits about an inch or a little more lower with that set up and the suspension still works good. Much like a longer 146mm or 146.5mm on a stock YZ. I messed around with that set up for a while. If you are short or want a REALLY planted feel in the turns, it's a viable option.
The 142mm F arm jacks the back end up about an inch and a half and apparently throws the linkage ratio way out of wack. It was way off and handled crazy to me. I can't imagine anyone liking that set up.
Then I got two adjustable Devol arms and that gave me a very wide range of adjustment and I played with a bunch of different settings and there was a 143.5mm setting. That got me right at the stock numbers for fender bolt to axle and I liked the suspension action the best with the shock valving I had. After riding with that for a while I was solid with it and found the PC arm was 143.5mm and just went with it.
So actually, you could go with the Devol arm, but I don't remember which one was the one that worked the best, but I was thinking it was the one for the 2008 and older F's. You'd have to contact Devol to get that info because they don't have specs for that arm on their website. They do the newer one and it doesn't have a 143.5 setting, so it must be the older one, but you'd have to verify that with them.
Sorry, the link is long gone.
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