Rear Wheel Bounce

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#1
my bike has a problem with the rear wheel bouncing up at higher speeds. after i shift into 4th gear it like instanly starts to bounce. I weigh 150 pounds and have all the suspesion settings at almost as soft as they go. and suggestions woudl be helpful.

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1993 KDX 250
Yes it's FAST, NO you can't ride it!
 
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#2
what type of ground are u on? the only thing i can think of is a traction problem. if you are on like cement sand somehow (don't ask me the logic behind it) when accelerating hard the tire will lose traction then gain it causing it to bounce. that also has alot to do with suspension. on pavement when my brother gives the truck some nut to make the tires spin we hop just like u said . i've seen it plenty of times but i don't know why it happens.
(i believe the traction problem could be irregular wear on the tires. see if your tires are more worn on some spots then others. its the only thing i can think of)

my 2 cents

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ah hick

[This message has been edited by new hampshire hick (edited 03-27-2001).]
 
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#3
I assume you don't mean that it kicks the rear end up like after going over a bump. Do you have a bunch of Slime or other stop leak stuff in the innertube? Might have a bent rim too. How are the spokes? The rim/hub might not be running true to each other.

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Derek
'00XR400
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#4
I am on mostly sandy condtions with a little bit of black dirt here and there.It is a brnad new tire or was like a month ago so it can't be worn more in one spot than the other.I don't have any leak stop stuff(i.e. Slime)in the tire and my spokes were just checked and my rim is perfect. Could it be my suspension settings are off? My brother thought it might be a problem with my setting on the rebound on the rear shock.Would this make a difference?Thanx for the problem solving power(or at least the thoughs)

Hopping in Wisconsin,
kevin

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1993 KDX 250
Yes it's FAST, NO you can't ride it!
 

RM_guy

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#5
The rear wheel can bounce because either the rebound or compression is too soft. The rebound controls how quickly the wheel returns to the ground. The softer it is set, the faster it will return. A too soft setting can cause the rear wheel to kick the rear end up on jumps.

The compression setting controls how fast the suspension collapses. If the compression is set soft, the rear wheel will move up quicker. As it is moving up it is compressing the spring and building up energy for the return trip. The farther the spring compresses (soft compression will allow it to compress further) the faster the rear wheel will return to the ground (which is compounded by a soft rebound setting).

The combination of soft rebound (fast return of the wheel to the ground) and soft compression (fast upward movement of the wheel) can cause the wheel to bounce.

First set your rebound and compression to stock settings. Play with the compression first by adjusting it soft and then hard 1 to 2 clicks at a time. After each adjustment, ride the bike and observe the results. Adjust it past the point where it feels good and then move it back so you know you have optimized it. Do the same with the rebound and then repeat the process with the compression (changes in the rebound can affect the compression).

Also, make sure the sag is set correctly before you adjust anything.

I hope this helps.

Good luck


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Sage

dirtbike riding roadracer
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#7
When was the last time the shock was serviced? I just fixed a 93 KX 250 with a similar complaint, turns out the seal head was leaking for quite some time and leaked almost all the oil out, resulting in a pogo-stick ride. ??? Your chain is'nt skipping from being too loose or worn sprockets is it?

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Sage Wilkinson, KDX Link 1
 
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#9
If you go to MX-Techs web site they have an excellent guide to tuning your suspension. You have gotten some good info here, but for the complete set-up, try MX-Tech.

vetwfo'er

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99 WR400f, White Bros E-Series silencer and tapered head pipe. YZ seat and tank. Thumper rad guards, works frame guards, scots steering damper. Soon to be MX-Tech suspension. SETRA, AMA, Happy Ramblers MC.

97KDX220, FMF Rev pipe and silencer, renthals.

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#10
Well i don't know about the service record because i just got the bike like last year.If the seal was broke would you see any oil anywhere?my chain and sprockets are brand new and the tire hops no matter if it is tight or loose.
 

MikeT

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#11
Kevin, RMGuy is correct. I also believe you have your rebound setting too soft. Is you set everything to its softest setting its getting close to simulating a blown shock, one with no dampening. Start with the stock settings, sag included. If that doesn't work, get the shock serviced.
 
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#12
mike and rm-guy thank you soo much. over the weekend i tried it and it sure made a differece. it seemed to not go as good in the sand so i just made the tire pressure a little lower and its good as ever. i still have a little bit of playing around to do but as far as the rear wheel hop, that is no more. once again i woudl liek to thank you 2 for helping me fix this annoying problem. I also checked the spokes which were way out of wack so i will have to watch them more closely now so between the 2 in work out perfect.
kevin
:cool:

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1993 KDX 250
Yes it's FAST, NO you can't ride it!
 

RM_guy

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#13
Glad to hear it worked out for you.
 

MikeT

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#14
Mike T: No problem, RM_Guy and myself were just doin' our jobs.

(Mike T and RM Guy tip their hats/helmets)

RM_Guy: All in a days work.

(MikeT and RM_Guy kick start their bikes and ride on into the sunset to help another). :)