Posts
1095
Joined
6/29/2014
Location
Temecula, CA, USA
Star Racing running longer swingarms?
Upgrade to enjoy this feature!
Vital MX fantasy is free to play, but Premium users receive great benefits. Premium benefits include:
- View and download rider stats
- Pick trends
- Create a private league
- And more!
Only $10 for all 2026 SX, MX, and SMX series.
a fair few years ago, but Kawi team was using KX500 swing arms at one point on the 250fs for a similar reason. so wouldn't be surprised if Star are doing something the same
Rumor was they're using 2010-2013 Yz450f swingarms. They're in the neighborhood of 13mm longer and bolt right on. I know of at least one vital member who has tried it out himself. Not sure if Star is still using them. Inquiring minds...
Someone would have protested that by now. Homologation only lasts for 5 years.
I think it was the previous gen swing arm 2017 or 18 I thought.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
They have different options on swingarms that they use from other models.
guys in the 2023 YZ450 thread are using 2017 (ish) SA's. I think they are approx 13mm longer. What does this do anyway
Longer wheelbase better stability. Shorter wheelbase stability goes down but turning is better. 13mm is quite a bit. A offset set of clamps or races on the front can only do so much. Generally Zx you want the shorter wheelbase due to a lot of turns and less high speed sections and outdoors the wheelbases is longer for high speed sections and stability over bumps.
They could go back to 2019 during this past season. I'm pretty sure that you couldn't use something off of a different model bike, if the pieces were different. For example, if they used a longer swingarm for the YZ450X than for the YZ450F, you couldn't use that because the YZ450X isn't homologated. Even though the YZ250F is homologated, if it had a different length swingarm on it then it wouldn't be 'legal' to use it on the YZ450F because they are different models.
Could be wrong, though, and with the AMA you just never quite know how they will enforce a rule on any given day..........
I don't believe the swing arm is covered under homogulation. The frame can be strengthen but otherwise not altered and the cases can't be altered. But I'd imagine swing arms from any year or even fully factory would be legal similar to factory hubs and transmissions.
the longer swing arm is used so they can run 13/50 gearing without having to run the axle farther forward than the stock 13/49. With this SA they can run the gearing they want and keep the axle back.
Not saying it is a pro or con, but longer swing arm would also put more weight on the front wheel. Something to consider.
One people are using 2023 model is from 2017 bike and only difference is it has 13mm longer hole for your rear axle. With that one you can use same gears but longer chain to move wheel back.
The 14-17 YZ450F swingarm (15-18 YZ250F) has a longer dropout length, allowing you to run the axle back further if desired.
Now, with that said, all of the guys running out and buying these used swingarms for their new 23s just because Star is supposedly doing it need to take a chill pill and think about what they're doing for a minute. What specific problem with your bike are you looking to solve? Is it something that absolutely cannot be managed by changing gearing, suspension settings, bar position, etc? This is how people go down a rabbit hole and chase their tail indefinitely, simply bolting a part onto your bike because you saw the factory team and a few people on the internet do it is not a recipe for success, unless you have truly nailed down a very specific handling problem that you would like to address that is clearly evident for your riding style and the conditions you tend to ride in. Bolting on parts and hoping it's "better" (which can be a very subjective and situationally dependent criteria) is not a strategy, I've been there before and I've learned slowly over the years to work backwards from a problem to find a solution, rather than bolt on a solution and look for a problem it supposedly solves. Star obviously believes there is a benefit for their riders, but that doesn't necessarily mean that the stock bike needs that update.
Looking at the rules for frame and swingarm it looks like you can add but not remove. It does say from the same model year.
The swingarm subsection just says "an originally homologated model of the same manufacturer"
That could definitely be a 'gray area' I would think. If you (or more importantly an AMA official) interpret it as any currently homologated model from the same manufacturer, then that means that a 250 swingarm could potentially be used on a 450 or vice versa, but the 5-year rule would still be in effect. Would also rule out something like an X model that may have had a longer swingarm, etc.
Good info thanks guys.
I’ve got a ‘24 250F on order and IF I find it a little more unstable than I care for, and after I play with things like sag, fork height, clickers, etc, I’m thinking it would be cheaper to pick up a used longer swingarm off eBay to try out, as opposed to a $700-$1000 set of triple clamps
Pit Row
Ability to use the 250 arm buys an extra year on the 5 year rule, because the 250 is a year behind the 450 on update cycle.
You're not accomplishing the same thing by changing out a swingarm for clamp offset, those are two entirely different tuning points and will not have the same effect. Clamp offset will change trail without changing rake, putting a longer swingarm on the bike will potentially change rake and trail, as well as weight bias. Changing sag will also change rake and trail. My point is that there are a lot of different factors at play and it's easy to go around in circles, as I have many times (and still do if I'm being honest, I'm not tuning genius that's for sure. . .), so really nailing down a problem is crucial. Also go in with an open mind, I don't care what anyone on Vital says, I don't care what Keefer says, and I don't care what any magazine says about a bike, see how it works for you and don't get caught up in internet rumors. I've ridden a lot of "unrideable" bikes and not had anywhere near the difficulties that people proclaim, the engineers who design these bikes aren't nearly as stupid as many want to believe and straying drastically from stock settings sometimes isn't the right move.
Yes totally understand that it’s a totally different mechanism. My point was that it would be a much cheaper experiment to see if I liked how it affects the bikes handling opposed to buying a $1k triple clamp setup. I see swingarms on eBay for $100. If I don’t like it no big loss.
and again, this is only IF I even feel there is an issue, And I can’t resolve the issue with fine tuning.
If you're new 2024 - 250f is ridden on tighter or slower courses, you will love it. High speed rough sand - not so much. At least i can't figure it out on these tracks.
The one thing with this new 23 450 was Yamaha suggested 95mm sag and the forks 7mm up in the clamps. I don't think i've ever seen anyone or even the mag test bikes set up this way. Makes me wonder how they came up with this ??
I think most bikes are much better than what those people that have never ridden them have to say about them
It does not say that
The Key 2 words ( well, they are All key words in that sentence) that allows the use of another Models Swingarm, are :
Originally Homologated.
Now, in my three jobs, one of which is just me pottering about in my home Workshop and making 'things' (heaven , in other words) but the other two being heavily written / regulation / rules / strictures based, from my experience in those worlds of gobbledegook, well, that sentence is pretty bloody open.
Without a reference to either a current / within 5 years of homologation Specific Cut-Off , well, they can put on Any Swingarm from a previously homologated model made by them : Yamaha.
NuAxle offset front axle is just 100-150 dollars. Goes from 20-24 offset just by turning axle. Read more from Keefer site.
Hadn’t heard of that. I’ll check it out
https://www.keeferinctesting.com/nuaxle-adjustable-offset-axle/
If you put a 116 link chain on the stock swingarm it'll move the axle back ~3/4 an inch depending on gearing. I've been running my last 2 bikes this way with very positive results, and no need to purchase an old model swingarm.
with 13/49 gearing this is fine, but not with 13/50. The longer swingarm gives just enough room for chain adjustment.
Post a reply to: Star Racing running longer swingarms?