High speed chop tank slapping

ben5020
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ben5020
I can’t for the life of me get this bar swapping sensation to go away when I’m on a rough track at high speeds. It’s sprung and valved for my weight and riding ability, 17 fc350 kyb a kit front forks, bladder conversion on the rear with pro circuit linkage. I was at englishtown the other week and got her dialed in pretty well but then I go to field of dreams which seemed to have a harder base so the chop is more violent when it comes to bar banging. What do you guys suggest? I tried Comp/rebound settings but eventually got lost. Thanks for any and all help. Oh and maybe it’s me and my short stature bc my 15 yz250f and 14 crf250r did the same stuff at high speeds with fc tunes suspension
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Paw Paw 271
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Paw Paw 271 3/14/2018 5:52am
3/14/2018 5:52am Edited Date/Time 3/14/2018 5:52am
Lower the fork legs in the triple clamps about 5mm or add about 5mm sag in the rear.

Paw Paw
ben5020
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ben5020 3/14/2018 6:45am
3/14/2018 6:45am
Unfortunately the forks are about as low as they can go, I had the sag at 110 but the front end didn’t seem to like that very much so I went to 106. At 110 the forks were very harsh feeling in rough sections
kb228
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kb228 3/14/2018 6:55am
3/14/2018 6:55am
Is your stem nut tight or are the bearings worn out? I had the same issue on my kx450. Replaced the bearings and torqued the nut and its all good. Best sign is bars flopping to one side on the stand.

Also you might be hanging over the front of the bike too much.
ben5020
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ben5020 3/14/2018 7:25am
3/14/2018 7:25am
Bike has around 30 hours on it don’t think the bearings are bad just yet, pretty sure I torqued everything when I installed the triples but I’ll check again. Too far forward can cause head shake? I figured more weight up front would lessen it

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BobPA
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BobPA 3/14/2018 7:54am
3/14/2018 7:54am
Add a bit of air pressure, try and get the forks a bit higher in the stroke.
ben5020
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ben5020 3/14/2018 8:08am
3/14/2018 8:08am
Kyb spring forks. But yes I did go up a few click on compression and it helped but then would push a little more in the turns. Maybe I’m just asking for to much out of these a kit forks
ra450
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ra450 3/14/2018 8:45am
3/14/2018 8:45am
Try to speed up the rebound in the forks.
kb228
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kb228 3/14/2018 8:52am
3/14/2018 8:52am
ben5020 wrote:
Bike has around 30 hours on it don’t think the bearings are bad just yet, pretty sure I torqued everything when I installed the triples but...
Bike has around 30 hours on it don’t think the bearings are bad just yet, pretty sure I torqued everything when I installed the triples but I’ll check again. Too far forward can cause head shake? I figured more weight up front would lessen it
If you lean forward you compress the forks thus lowering the front of the bike. Leaning back lowers the rear and gives more stability and less headshake.

Amount of hours is irrelevant sometimes. We have all seen brand new bikes and cars break. Still something to look at just to be sure. Especially if you had it apart.

RyanLester761
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RyanLester761 3/14/2018 11:44am
3/14/2018 11:44am
Seems like you've covered most of your bases, but I suggest tightening the head nut so the bars don't flop on their own weight- (also stated above) but to emphasize, you definitely want some resistance on the turning. Also, roll the bars back a tad and squeeze the bike with your knees. Maybe drag the rear brake, depending on the situation.
RyanLester761
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RyanLester761 3/14/2018 11:49am
3/14/2018 11:49am
ra450 wrote:
Try to speed up the rebound in the forks.
Agreed. ^^

I remember MXA always saying if your forks are too soft, you will get headshake and they suggested going to stiffer springs. Obviously, the front end would drop, steepening the rake. I imagine the stiffer springs help speeding up the rebound too. The forks could be packing and not contacting the ground on throttle chop. A quality slow-mo video of you riding the bike could help determine if this is happening.
easydoesit
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easydoesit 3/14/2018 12:15pm
3/14/2018 12:15pm
Are you accelerating, decelerating or maintaining speed?

Some other things to check:
Front wheel bearing excess play?
Is the front wheel true?
Front tire seated properly?
Naanak
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Naanak 3/14/2018 2:21pm
3/14/2018 2:21pm
Same problem same tracks you ride. 14 Crf250r and 17 Crf450r. I’ve tried all the common suggestions and nothing works. I blame myself. I’ve been told by a local suspension guy that my suspension is to soft but haven’t had it done yet.
m21racing
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m21racing 3/14/2018 3:18pm
3/14/2018 3:18pm
Turn the comp clickers on forks all in, and see if the headshake issue gets any improvement. That's a way to troubleshoot your valving.
ben5020
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ben5020 3/14/2018 3:19pm
3/14/2018 3:19pm
Naanak wrote:
Same problem same tracks you ride. 14 Crf250r and 17 Crf450r. I’ve tried all the common suggestions and nothing works. I blame myself. I’ve been told...
Same problem same tracks you ride. 14 Crf250r and 17 Crf450r. I’ve tried all the common suggestions and nothing works. I blame myself. I’ve been told by a local suspension guy that my suspension is to soft but haven’t had it done yet.
I was under the assumption that too stiff of suspension will cause headshake, wonder which one is true? Stiff or soft is to blame.
ben5020
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ben5020 3/14/2018 3:21pm
3/14/2018 3:21pm
easydoesit wrote:
Are you accelerating, decelerating or maintaining speed?

Some other things to check:
Front wheel bearing excess play?
Is the front wheel true?
Front tire seated properly?
It’s when I’m accelerating and once it gets violent I let off. Think I’m 4th gear almost pinned. Wheel and tire are good
m21racing
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m21racing 3/14/2018 4:54pm
3/14/2018 4:54pm
Go in on hc nut 1/4 and see if any improvement.
Naanak
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Naanak 3/14/2018 4:55pm
3/14/2018 4:55pm
ben5020 wrote:
I was under the assumption that too stiff of suspension will cause headshake, wonder which one is true? Stiff or soft is to blame.
When I called FC about the issue they had me go softer on the clickers (did not help). The local guy said I needed to go up a spring rate and much stiffer valving. So I honestly have no idea.
RyanLester761
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RyanLester761 3/14/2018 10:41pm
3/14/2018 10:41pm
Rear spring too stiff? Maybe the pc link makes it stiffer on the initial stroke and rear isn't settling...???

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ben5020
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ben5020 3/15/2018 4:03am
3/15/2018 4:03am
RyanLester761 wrote:
Rear spring too stiff? Maybe the pc link makes it stiffer on the initial stroke and rear isn't settling...???
My sag numbers are fine so I don’t think it’s a rear spring/shock issue. Maybe I’m just too far forward and it’s getting all whacked out bc of it?
Johnny89superbike 3/15/2018 6:09am
3/15/2018 6:09am
My RMZ450 always gets headshake with high speed throttle chop if fork rebound is too slow. Never have any trouble now l have less offset triple clamps.
kb228
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kb228 3/15/2018 6:10am
3/15/2018 6:10am
RyanLester761 wrote:
Rear spring too stiff? Maybe the pc link makes it stiffer on the initial stroke and rear isn't settling...???
ben5020 wrote:
My sag numbers are fine so I don’t think it’s a rear spring/shock issue. Maybe I’m just too far forward and it’s getting all whacked out...
My sag numbers are fine so I don’t think it’s a rear spring/shock issue. Maybe I’m just too far forward and it’s getting all whacked out bc of it?
Thats what i told you fam. Ass over the fender over chop. Look at the pros
CSAR FE
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CSAR FE 3/15/2018 1:39pm
3/15/2018 1:39pm
I’m running a 17 FX450, and I’ve found that anything less than 107mm of sag will make the front end very unstable. As a matter of fact, yesterday I decided to try 105 and ended up with the same problem as you over the whoops. Went to 108mm, problem solved.

As others have mentioned, too slow of rebound on the forks can do it also.
mattyhamz2
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mattyhamz2 3/15/2018 3:01pm
3/15/2018 3:01pm
Naanak wrote:
Same problem same tracks you ride. 14 Crf250r and 17 Crf450r. I’ve tried all the common suggestions and nothing works. I blame myself. I’ve been told...
Same problem same tracks you ride. 14 Crf250r and 17 Crf450r. I’ve tried all the common suggestions and nothing works. I blame myself. I’ve been told by a local suspension guy that my suspension is to soft but haven’t had it done yet.
ben5020 wrote:
I was under the assumption that too stiff of suspension will cause headshake, wonder which one is true? Stiff or soft is to blame.
I've seen it happen from both scenarios. Tried to explain that to a buddy after his suspension tuner left the rear alone and went up on the fork spring rate. He couldn't figure it out. Finally had a more well known tuner look at them and he backed up everything I said.

I have also seen it happen when the front is too soft and riding too low in the stroke. Suspension in an interesting topic and I love learning about it.
ben5020
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ben5020 3/16/2018 4:04am
3/16/2018 4:04am Edited Date/Time 3/16/2018 4:05am
Radfonz wrote:
get stronger arms maybe?
Hahahahaha I’ll be sure to eat my spinach and see if it helps
reded
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reded 3/16/2018 4:18am
3/16/2018 4:18am
My '14 250SX had severe headshake in decel chop, to the point that it would nearly rip the bars from your hands. I don't claim to know a lot about setup and tried numerous solutions from "experts" to no avail. I now have a '16 FC350 that came with a Ride Engineering stabilizer. I know that it's a band-aid for shitty setup but I've yet to feel the bars twitch under any circumstances. I highly recommend it if all else fails and you're tired of chasing your tail.
slipdog
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slipdog 3/16/2018 6:47am
3/16/2018 6:47am
I had a '17 TC 250 with AER forks, no headshake what so ever...
mattyhamz2
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mattyhamz2 3/16/2018 8:46am
3/16/2018 8:46am
slipdog wrote:
I had a '17 TC 250 with AER forks, no headshake what so ever...
But you also know a lot about suspension and how to set it up properly Whistling
Bruce372
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Bruce372 3/16/2018 8:49am
3/16/2018 8:49am
slipdog wrote:
I had a '17 TC 250 with AER forks, no headshake what so ever...
You didn't get the memo air forks are no good?
ben5020
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ben5020 3/17/2018 5:10am
3/17/2018 5:10am
reded wrote:
My '14 250SX had severe headshake in decel chop, to the point that it would nearly rip the bars from your hands. I don't claim to...
My '14 250SX had severe headshake in decel chop, to the point that it would nearly rip the bars from your hands. I don't claim to know a lot about setup and tried numerous solutions from "experts" to no avail. I now have a '16 FC350 that came with a Ride Engineering stabilizer. I know that it's a band-aid for shitty setup but I've yet to feel the bars twitch under any circumstances. I highly recommend it if all else fails and you're tired of chasing your tail.
I ordered the bracket from ride engineering and will weld a post into my bike in the near future, maybe it’ll help out a littl

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