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4/4/2023
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Hello everyone,
I saw online many kit for lowering the yz450f and seems like the link has been the same for a long time now (form 2018 at least).
I would like to understand how the link ratio changed with this lowering kit. From my experience elongating the pull rod the link ratio is going to move to a more linear or regressive behavior, but I cannot find any graph about the original link ratio evolution along the stroke, neither how it change with this aftermarket kits.
Do anyone have some info about that? Any graph or number?
You're probably not going to find a plot like that because most companies selling a lowering link don't do any sort of analysis or measurement, they just make a longer link. If their objective is to simply lower the rear end, that will do it.
The only ones that might have a plot like that are ones that (correctly) re-designed the knuckle as well as the link since they'd need to know the motion ratio curve to make any sort of improvement. There are only a handful of companies who do that and few that would share the curves.
Regardless, you're correct in your thinking. The longer the link, the more regressive the curve. It's not a drastic change so long as the length doesn't increase much. But if you get a much longer link (5 mm or more), then it gets to be a pretty big change and you'll lose bottoming resistance. Here's the curves vs link length change for the last generation KTM. Don't have one for the Yamaha, sorry. It will be different, obviously, but a similar trend.
Good lord that's a nice answer.
Thanks Luxon for taking the time to drop knowledge like that.
JGR?
Is that a question towards me? If so, can you be more specific?
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