Rear end bucking hard

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NightBiker07
Posts: 1942
Joined: April 16th, 2008, 8:59 pm
Location: USA

Rear end bucking hard

Post by NightBiker07 »

When I get into some really hard-hitting whoops, the rear end bucks really high, its like the rear end is a pogo stick. In moderate whoops, the bike handles great, in short choppy bumps it handles great too. jumps great too.

But, really hard, deep whoops make the rear end bounce like crazy. When I put ALL my weight as far back as I can, it helps a little, but the damn seat beats the hell out of my ass.

The shock doesnt seem to be bottoming out.

Never really got into tryign to fine-tune the clickers on any bike, I find a compression setting I like then have always set the rebound at the same number of clicks, so I have no idea how to adjust them to change specific handling issues. I know, I need to play with it a LOT so I can learn it, but when I go riding, it isnt really often, and devoting the day to "test n tune" just seems like a lot less fun, so it hasnt happened yet.

Just hoping someone can point me in the right direction as far as what to fiddle with to get it handling better.
2000 CR250, pipe, filter, Vforce

1980 XL80s
1969 Broncco TX-6

Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
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NightBiker07
Posts: 1942
Joined: April 16th, 2008, 8:59 pm
Location: USA

Post by NightBiker07 »

Nobody?
2000 CR250, pipe, filter, Vforce

1980 XL80s
1969 Broncco TX-6

Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
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Nodge
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Joined: October 31st, 2007, 6:12 pm
Location: Saskatchatoon

Post by Nodge »

Try a slower rebound setting if everything else seems ok.
Yah, I'm from Saskatchetoon!

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scooter5002
Posts: 425
Joined: July 31st, 2010, 5:22 am
Location: Tillsonburg On

Post by scooter5002 »

Sorry Ern I just noticed this. Not here much when I'm out west working and on the I Phone.
You say your shock isn't bottoming, is that through the big whoops or at all? Would be really helpfull if you had someone who could watch the bike as you hammer through. It can be one of a couple things, or a combination of things.
First, how old is your shock oil? That's crucial. If you don't remember, it's time for a service. Shitty oil can't be fixed with clickers.
When was the last time you checked your sag? Be sure it's around 100 mil, I ran 95 on my steely, a little tighter than stock recommendation.
Your forks need to be in good shape too, because if the back end is overpowering your front, you'll have some issues. Same thing with fork oil. If you don't know when it was last serviced, it's probably time.
If you're good there, and have no one to watch the bike for you, set all your clickers back to stock. If the suspension has been valved for you, put it back to the recommended setting.
Now go ride a section that gives you trouble, and turn ONE setting 2 clicks. Doesn't matter which one. If you don't like the change, turn it back. If you thought it was better, try 2 more clicks. Now try the other end. Same process. NEVER adjust both ends at the same time, because if it sucks, you won't know why. You should really only be working with Low Speed Compression and Rebound. Your Hi Speed is more ride height and braking/chatter bump related, although it will affect everything somewhat.
If you ride the same section for a half hour you should be able to dial your bike in pretty quickly. Rule of thumb though, if everything is in good shape overall, big sandy whoops mean stiffer comp on both ends and slow rebound down, moreso on the shock. The forks will feel like they're bouncing back in your face, and you'll know it. Again, 1 setting at a time, never more than 2 clicks. If you're on a Kayaba equipped 500, remember that rebound and comp in the shock have a slight crossover onto each other. Confused yet? Lol. It's not rocket science, but it's a little complicated. Good luck.
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NightBiker07
Posts: 1942
Joined: April 16th, 2008, 8:59 pm
Location: USA

Post by NightBiker07 »

scooter5002 wrote:Sorry Ern I just noticed this. Not here much when I'm out west working and on the I Phone.
You say your shock isn't bottoming, is that through the big whoops or at all? Would be really helpfull if you had someone who could watch the bike as you hammer through. It can be one of a couple things, or a combination of things.
First, how old is your shock oil? That's crucial. If you don't remember, it's time for a service. Shitty oil can't be fixed with clickers.
When was the last time you checked your sag? Be sure it's around 100 mil, I ran 95 on my steely, a little tighter than stock recommendation.
Your forks need to be in good shape too, because if the back end is overpowering your front, you'll have some issues. Same thing with fork oil. If you don't know when it was last serviced, it's probably time.
If you're good there, and have no one to watch the bike for you, set all your clickers back to stock. If the suspension has been valved for you, put it back to the recommended setting.
Now go ride a section that gives you trouble, and turn ONE setting 2 clicks. Doesn't matter which one. If you don't like the change, turn it back. If you thought it was better, try 2 more clicks. Now try the other end. Same process. NEVER adjust both ends at the same time, because if it sucks, you won't know why. You should really only be working with Low Speed Compression and Rebound. Your Hi Speed is more ride height and braking/chatter bump related, although it will affect everything somewhat.
If you ride the same section for a half hour you should be able to dial your bike in pretty quickly. Rule of thumb though, if everything is in good shape overall, big sandy whoops mean stiffer comp on both ends and slow rebound down, moreso on the shock. The forks will feel like they're bouncing back in your face, and you'll know it. Again, 1 setting at a time, never more than 2 clicks. If you're on a Kayaba equipped 500, remember that rebound and comp in the shock have a slight crossover onto each other. Confused yet? Lol. It's not rocket science, but it's a little complicated. Good luck.
Shock oil is probably stock. Forks were just rebuilt by me, they were leaking pretty bad. WHen I rebuilt them, it fixed all my front-end issues (barely any oil left in the tubes)

The whoops are hard pack dirt. Front end feels great riding through anything, and the bike flies straight without any extra-special manipulation, so I dont think the rear is overpowering the front to that extent, or the bike would land nose-heavy like a bitch!

Through the smaller whoops, the bike floats over them pretty good, but the larger ones really kick the rear end UP.

I will have to get someone to record a few hard passes so I can see what is going on.

I will probably pull out the shock this winter and get it serviced. I did set the sag right when I got the bike, the guy I got the bike from was double my weight, so it was REALLY stiff.
2000 CR250, pipe, filter, Vforce

1980 XL80s
1969 Broncco TX-6

Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
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