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Opinions on Shock adjustment

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2013 KX450F.  I did a SSS fork conversion and starting to get the forks dialed in but the shock is giving me some fits now.  It feels great on jumps, take offs,  even not too bad in braking/accel bumps.  But the problems i'm having is it seems to want to slam the front down in rollers, i cannot seem to loft the tire.  And, traction is not too good, like coming out of a turn i cannot get good traction.  think I have sag set up to 106mm.  I am thinking HSR shim adjustment but wanted your guys opinions

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Are you sure the fork length is correct

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Sounds extreme , what about the rear suspension action on landings and sharp bumps

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Except for traction it feels awesome.  Square bumps and Accel decel bumps little rough but not overly rough.

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At track now and tried adjusting rebound and hsc and not really getting better.  Maybe its cause I hammer throttle out of turns, still should be getting decent traction though. Ill try stiffening lsc, can't go softer then it bottoms.  Want to send shock in but ill have to buy a stick valve, have gold valve now

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If you run out of ideas on shock adjustments, how about trying faster fork rebound to transfer some weight to the back when accelerating.

Might improve the forks thru rollers as well (your original post).

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Just now, mlatour said:

If you run out of ideas on shock adjustments, how about trying faster fork rebound to transfer some weight to the back when accelerating.

Might improve the forks thru rollers as well (your original post).

Kinda what I was thinking, I'm wondering if they're extending enough/fast enough.

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I have the forks adjusted for good turning, if i speed up rebound it will understeer, not sure what front sag is.  I played with everything and only thing seemed to help a little was loosening up rear sag.  Didn't check the numbers but it went a little better. I am giessing its around 106-107

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Did the height of your bike's front end get taller or shorter when you did the fork swap?  That matters, because it changes the bike's approach angle, which changes the angle that your swing arm is at (relative to level ground) while you're riding. 

For an easy way to think about it, lets say your swing arm used to sit perfectly level while accelerating.  So when you hit a bump, the rear portion of the swing arm would be higher than the front portion of the swingarm, and that means that the wheel would travel ever so slightly toward the middle of the bike, because it traveled to higher position on the swing arm's arc.  When the shock rebounds, it actually travels away from the bike slightly as the swing arm returns to the level position.  Just like your hand moves away from your body when you move your elbow to 90 degree angle.  When the swingarm is level with the ground, the wheel will move backwards 180 degrees away from the direction that the bike is moving.  

Think of the swing arm's arc as something that moves the rear wheel toward and away from the ground at a certain angle.  If you raise the front of the bike so the bike sits 3 degrees above level, it makes that swingarm angle steeper by 3 degrees as well.  So the shock is going to kick the rear wheel back down, and the wheel will still travel away from the middle of the bike, but since you're bike is riding steeper, the wheel will not move 180 degrees away from the direction that the bike is moving.  

 

 

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Just now, dirtjumpordie said:

Did the height of your bike's front end get taller or shorter when you did the fork swap?  That matters, because it changes the bike's approach angle, which changes the angle that your swing arm is at (relative to level ground) while you're riding. 

 

 

Is swingarm angle very important on a dirtbike? I know on roadies there's an ideal angle (somewhere around 12deg from memory) but with all the bumps and stuff I'd have thought it wouldn't matter too much offroad.

It's not something silly like tire pressure is it?

Edited by DEATH_INC.

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4 minutes ago, DEATH_INC. said:

Is swingarm angle very important on a dirtbike? I know on roadies there's an ideal angle (somewhere around 12deg from memory) but with all the bumps and stuff I'd have thought it wouldn't matter too much offroad.

It's not something silly like tire pressure is it?

 

Yeah swing arm angle matters probably more on motocross bikes IMO.  Even very small changes in motocross bike geometry make big differences.  Thats why things like changing to a different fork changes the way the shock interacts with the bike's position and even traction. 

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I measured the forks and they were exactly the same length.  Ill get the front sag in a bit.

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Same overall length but what about axle lug placement, centerline, height etc.

Anything that can alter geometry.

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I measure from middle of axle lug to top of forks when I compared amd they were the same.  I had to have spacers machined cause lugs were different thickness but the tire is centered. As far as i could tell it all looked pretty much identical, dimension wise

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