Posts
5391
Joined
10/1/2013
Location
Davis, CA
US
JM485
12/5/2017 7:55pm
12/5/2017 7:55pm
Edited Date/Time
9/28/2022 10:43am
Well, after finally getting this swap figured out once and for all, I figured I would share how I went about putting the modern style four stroke swingarm on my 15 YZ250. This all came about after an unfortunate failure at the Reno endurocross this year. As second practice started, I proceeded to launch the finish line jump and get set to begin my fast lap. Upon landing, however, my chain guide snapped off the swingarm and wrapped its was around my sprocket, breaking my hub and ending my day on the big bikes. I was obviously super mad at the time, but after some time to reflect I realized I should really count my blessings that it did not snap off on the lip, we would probably be having a very different thread right now. . . I basically went from hero. . .
. . . To zero just like that. . .
So, I basically had a choice to make, replace it with another old design swingarm, or update the bike with the new style swingarm. I chose the later, and opened up a much bigger can of worms then I expected. After some research, I came across this article from MXA, and used it as my guide for the project:
https://motocrossactionmag.com/ask-the-mxperts-can-i-put-a-yz450f-swing…
Now, according to them you can simply bolt the new swingarm and linkage onto the two stroke, as long as you have the wheel and brake hanger. Following this guide, I bought a swingarm and linkage off of a fellow Vital member's blown 2014 YZ250F, as well as a hub, spokes, and rim (18" this time around). Upon receiving the swingarm, I realized that I would need my swingarm spacers, which was no big deal since they slipped right into the 450 swingarm. The issue came when I bolted the linkage up. Yes, the linkage will bolt up, but you'd have to be a complete moran to think this is acceptable. The linkage was completely kicked over to the side, and any riding would have resulted in the pull arm digging into my frame and an unevenly worn shock. Naturally, I assumed the swingarm was bent, so I proceeded to contact the seller and make a complete ass out of myself convincing him to take the parts back, which he agreed to. I then went onto Ebay, and bought a used 2014 YZ450F swingarm.
Upon receiving the new swingarm, I bolted it onto the bike. To my surprise, I found exactly the same thing, linkage was completely off-center and would rub on my frame. The realization began to set in that the linkage mount on the new 450 swingarms is actually offset to the side slightly. I don't know who is writing articles for MXA, but if they were really "speaking from experience" with that article, there's no way in hell they would have been able to call this fit acceptable. I ended up calling the seller of the first swingarm, apologizing, and eating about $150 in shipping costs because I was clearly at fault. Thanks MXA, glad you did your due diligence before leading people astray with your article. . .
Now, I had to go about fixing it. After some careful measurements, I found that the linkage mount is offset .175" on the new swingarms. This meant I had to mill that amount from one side of the swingarm, and machine a spacer to take up the space on the other side. Here is what I came up with:
Here is how everything fit after the modifications. Everything lined up perfectly, and the pull arm was centered nicely between the frame mounts. Keep in mind, you will need the four stroke linkage as well in order to keep the rising rate the same (according the MXA so who really knows. . .), and I used a set off a WR250 since it was the same.
Looks pretty darn good on the bike to IMO, much better than the old design!
Now, most importantly, how does it ride? In a word. . .Awesome! I don't think that the linkage rising rate is quite the same as the old two stroke linkage, but to me the new setup is an improvement. I've always struggles with front end traction on this bike, and with this setup the back end had a little more holdup to keep things planted on the front. I can now run more sag and still have a balanced setup, which is great! I also feel that the back kicks a little less than previously, but nothing earth shattering. For someone with a perfectly good swingarm and linkage setup on their YZ, I don't think this swap is worth it financially for the performance gained, but if you want a project or have had a similar failure I would definitely recommend it. I have been told that the 09+ swingarms before they went to the reverse motor design will bolt right up with no offset on the linkage, but I have not confirmed this so proceed with caution. Why Yamaha doesn't do this from the factory I have no idea, it seems like a no brainer to me since the performance gain is noticeable.
Hopefully this little write up will guide others through the project and dispel a few rumors about this swap. If anyone has any questions please let me know, I only have two rides on it so far so I will be learning more about the bike over time. Watch out for misinformation out there, I figured a reputable website like MXA would have trustworthy information but apparently not. This whole fiasco cost me a decent amount is shipping, but more importantly caused me to miss the final round of the endurocross series in Ontario, which I had been planning n racing.
. . . To zero just like that. . .
So, I basically had a choice to make, replace it with another old design swingarm, or update the bike with the new style swingarm. I chose the later, and opened up a much bigger can of worms then I expected. After some research, I came across this article from MXA, and used it as my guide for the project:
https://motocrossactionmag.com/ask-the-mxperts-can-i-put-a-yz450f-swing…
Now, according to them you can simply bolt the new swingarm and linkage onto the two stroke, as long as you have the wheel and brake hanger. Following this guide, I bought a swingarm and linkage off of a fellow Vital member's blown 2014 YZ250F, as well as a hub, spokes, and rim (18" this time around). Upon receiving the swingarm, I realized that I would need my swingarm spacers, which was no big deal since they slipped right into the 450 swingarm. The issue came when I bolted the linkage up. Yes, the linkage will bolt up, but you'd have to be a complete moran to think this is acceptable. The linkage was completely kicked over to the side, and any riding would have resulted in the pull arm digging into my frame and an unevenly worn shock. Naturally, I assumed the swingarm was bent, so I proceeded to contact the seller and make a complete ass out of myself convincing him to take the parts back, which he agreed to. I then went onto Ebay, and bought a used 2014 YZ450F swingarm.
Upon receiving the new swingarm, I bolted it onto the bike. To my surprise, I found exactly the same thing, linkage was completely off-center and would rub on my frame. The realization began to set in that the linkage mount on the new 450 swingarms is actually offset to the side slightly. I don't know who is writing articles for MXA, but if they were really "speaking from experience" with that article, there's no way in hell they would have been able to call this fit acceptable. I ended up calling the seller of the first swingarm, apologizing, and eating about $150 in shipping costs because I was clearly at fault. Thanks MXA, glad you did your due diligence before leading people astray with your article. . .
Now, I had to go about fixing it. After some careful measurements, I found that the linkage mount is offset .175" on the new swingarms. This meant I had to mill that amount from one side of the swingarm, and machine a spacer to take up the space on the other side. Here is what I came up with:
Here is how everything fit after the modifications. Everything lined up perfectly, and the pull arm was centered nicely between the frame mounts. Keep in mind, you will need the four stroke linkage as well in order to keep the rising rate the same (according the MXA so who really knows. . .), and I used a set off a WR250 since it was the same.
Looks pretty darn good on the bike to IMO, much better than the old design!
Now, most importantly, how does it ride? In a word. . .Awesome! I don't think that the linkage rising rate is quite the same as the old two stroke linkage, but to me the new setup is an improvement. I've always struggles with front end traction on this bike, and with this setup the back end had a little more holdup to keep things planted on the front. I can now run more sag and still have a balanced setup, which is great! I also feel that the back kicks a little less than previously, but nothing earth shattering. For someone with a perfectly good swingarm and linkage setup on their YZ, I don't think this swap is worth it financially for the performance gained, but if you want a project or have had a similar failure I would definitely recommend it. I have been told that the 09+ swingarms before they went to the reverse motor design will bolt right up with no offset on the linkage, but I have not confirmed this so proceed with caution. Why Yamaha doesn't do this from the factory I have no idea, it seems like a no brainer to me since the performance gain is noticeable.
Hopefully this little write up will guide others through the project and dispel a few rumors about this swap. If anyone has any questions please let me know, I only have two rides on it so far so I will be learning more about the bike over time. Watch out for misinformation out there, I figured a reputable website like MXA would have trustworthy information but apparently not. This whole fiasco cost me a decent amount is shipping, but more importantly caused me to miss the final round of the endurocross series in Ontario, which I had been planning n racing.
I also want to change brake pedals to the sleeker 4 stroke one. No performance just looks cool.
This is for a 2009 450 swingarm and 2009 250F complete linkage, which all bolts right up without issue (no offset linkage issues like you had on the newer swingarm).
Nice job on the machine work too!
The Shop
BTW, thanks again for the help you gave me on my resume, I've been working at a job I got shortly after and I have to imagine that played a big role. I've also been following along as you develope the new triple clamps, it's been a really cool process and made me realize just how little I really know. I'm learning a lot in industry though, my Solidworks skills have definitely improved quite a bit, and I've learned about a few different manufacturing processes I wasn't aware of before.
The 250 and 450 are different the 450 is longer, so maybe because if this they also decided to offset the linkage.
2009 is known as the go to bolt up.
2010 is what I am looking at
And the 2014 mentioned here some work some don't.
2009 250 17d 22110 00 00
2009 450 34p 22110 00 00 (suppose to be longer)
2010 250 17d 22110 00 00 same as 2009
2010 450 33d 22110 00 00 different from 2009
2014 250 1sl 22110 01 00 different
2014 450 1sl 22110 01 00 different
-noted below that they suppersede 1sl 22110 00 00
So there may have been some kind of mid year change in 2014 because they changed to 01 in that column. 2013 had the 00 number but 14 was also the first year for the next generation.
In 2010 they changed the 450 to reverse engine but not the 250. I read in a review for that the shock was center mounted because there was no need for an airboot. So I would just stay away from any later than 2009 in the 450. However the 250 should work up until 2014 but it isn't going to be longer, but it will still be lighter.
Was looking into the swap a little bit myself just for the weight loss and cool factor. For those wondering the YZ125 and the YZ250 show the same part number and use the same swing arms so judging by that, this swap should be the same with both 125's and 250's.
Pit Row
the axle through the frame/swingarm is also 1mm smaller on the 4 stroke so you have to switch the bushings from the swingarm bearings.
Also the swingarm was about 5mm shorter than my 2 stroke swingarm
I just did the conversion myself on my 2011 yz250. Used a 2010 yzf450 swingarm, linkage & wheel & it bolted right up. I thought the 2009-2013 yzf450 & 2010-2013 yzf250 bolt right up (I forget why the 1 year diff or I may be just confusing it with the 22mm triple clamp conversion I also did).
I'll be posting a thread here soon :]
Also, you don't have to swap the axle, hub, bearings, axle blocks or brake carrier with the swingarm swap.
YAMAHA uses the same wheel set up on the "FX" 250 / 450 as they do on the YZ250X, which is the same as the standard YZ, but with an 18" rim and the "FX" and "F" use the same swingarm.
So the FX 250/450 has a '4stroke' swingarm(without the plastic plugs) but uses a 22mm axle? How do they fill up the 3mm play in the swingarm ends?
The problem as shown in my picture stays I guess, the shock on a 4 stroke is more located to 1 side?
Post a reply to: YZ250 Swingarm Update the Right Way (Not the MXA way)