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Yz 125 Speed Wobble/Rear wheel kicking..

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I have a 2002 yz 125 with a few of performance modifications. I've had this bikes for 1 week and really like it but this part scares me... The suspension is set up for a bit heavier rider I think and I'm 5'4 and 135 lbs. I was riding yesterday and I was getting really comfortable with the bike except I was getting huge speed wobble and sometimes my rear wheel kicks back and forth and I think that's just because its too stiff. What should I do? Just let off the rear spring a bit? Than what should I do for my front wheel? Thanks guys! This is my first post on here! (Just got new wheel bearings if that helps)

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I'm pretty new to bikes, but I had that same problem on my yz 250.... I tried setting sag (if you don't know look it up on youtube, its one of the most important settings)  my rear wheel spokes being loose seemed to be the cause of it... I did change to a newer shock because I had a leak. it seemed to hurt handling.. but I have not had a tank slapper since tightening my rear spokes.

Edited by yz250474

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As noted above, the most important thing you can do is have the bike set up properly.  If the springs are stock, you should be OK as far as spring rate.  If the bike does have non stock springs, you will need to get springs that match your weight.  You can tell if the spring rate is correct for the shock by comparing the free sag with the race sag.  Make sure you set the sag properly.  Small changes make a big difference, and the sag needs to be set with your riding gear on.  

 

You also need to check for wear/damage to wheels and suspension.  Check spokes, and all bearings for play (headstock, swingarm, linkage, wheel).  Make sure your forks are at the right height in the triple clamps, and make sure you follow the correct procedure for mounting the front wheel, allowing for fork alignment--a very common mistake. Check the drag on the headstock bearing.  Most riders prefer just a little drag.   Also make sure you rear wheel is aligned properly.  The tick marks on Japanese bikes are often misplaced.  I prefer to measure from a reference point on the swingarm based on the distance from the frame pivot.    

 

Once you get all this sorted, then you can delve into clicker settings.  But I would leave them at the manual listed "standard" setting until you get everything else in order.

 

I know this sounds like a lot if you are new to bikes, but it will become second nature soon, and it's easy to keep a bike set up properly once you develop some good maintenance and service habits.  Play bikes (like TTRs and XRs) don't have all these different settings to worry about, but they don't offer anywhere near the performance of a race bike.  

Edited by rpt50

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The compliment rpt50 verification list, also check that the fork tubes are set at the proper height in the triple clamps.

Some people raise the tubes slightly to make the bike corner a little faster but at the trade-off of some front end instability and headshake (wobble) when at speed.

Edited by mlatour

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