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Knock at the top of the stroke??

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So I picked up a used 2017 CRF450 last weekend and rode it yesterday for the first time. It has factory connection suspension done on it and works phenomenally. However, I noticed going through roller whoops that when I pull up hard, as the wheel is coming off of the whoop, there is a light knocking feeling. Like not enough to actually hear it, but you feel it in your hands. Just a light knock like there's a gap somewhere in the front end in something. Any ideas what it could be? I liken it to the feeling of when you're riding a really cheap mountain bike and you pull up theres a clunk as the wheel stays on the ground for a second while the suspension completely extends and tops out (this would be a very exaggerated example as the feeling in my crf forks is much much lighter, but it feels slightly similar and happens under the same type of circumstances).

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Sounds like badly bleed inner chambers or maybe steering bearings ?

winning by 4:1 lol

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I have seen & rode A buddy's 17crf 450  revalved by FC .The forks topped out in quick successive  hits such as whoops.As you described.  I disassembled them to verify some thing hadn't come loose I did not find anything.

It annoyed him & was sent back to FC & returned only slightly better, They did not find any thing wrong. This was early He just ended up selling it.

I had a 15 rmz w TAC fork do the same thing.  FC revalved   only in whoops & light front end situations that would have a High speed shallow fork impact. 2"- 3"

I offer no solution Other than what mog suggested . However I'm curious if Showa speced a bit too soft of A top out spring .

I have seen stiff mid valves  cause cavitation  on quick hits in whoops . This hinders  rebound refill & will top out as you mention.

If all else fails call FC .  

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2 hours ago, mxracer515 said:

I have seen & rode A buddy's 17crf 450  revalved by FC .The forks topped out in quick successive  hits such as whoops.As you described.  I disassembled them to verify some thing hadn't come loose I did not find anything.

It annoyed him & was sent back to FC & returned only slightly better, They did not find any thing wrong. This was early He just ended up selling it.

 

I see you're from Missouri, which is where I bought the bike... Mind me asking who your buddy is? 

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Maybe: too much spring preload, or play in the bushes, or a reb stack with very soft low speed damping, or unusually thin oil. Or maybe something is asymmetric in the forks so one top-out spring is doing all the work.

Otherwise as already mentioned: Head bearings loose. Too much air (and/or not enough oil vol/pressure) inside the damper. Stiff mid comp causing cavitation then no reb damping.

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