Today we want to share with you some modifications we have done to this late model KLR650 shock.

The customer decided it needed something doing after being continually un happy with the way the shock felt. It’s no secret that the suspension in the KLR models is significantly less complex than on the race models like a KX. The shock is a 40mm shock body with nothing separating the oil from the gas. Of course the KLR models are not meant for the intense terrain the motocross bikes are, but it’s still a shame Kawasaki choose to use such an outdated design.

The first thing we did was inspect the shock for any signs of defects or anything that may be affecting the way it works right now. Obviously any shaft or seal damage will relate to it not working how it should. Everything looked in good condition. We then tested it in standard form on the dyno to get a baseline on what its doing. Feel free to check it out below.

The dyno showed the shocks’ initial compression stroke was very stiff under light work and then too soft when put under larger force. What that means on the bike is small slow impacts feel stiff, but anything significant, like a hard landing results in the valving in the shock not being able to keep up and the shock bottoming out. It’s almost like it’s back to front from how you want it. This type of feel is not uncommon for factory suspension components, even modern motocross bikes. It tends to be a safe and cost affective way to get a mid feel that is just acceptable in the eyes of the corporate world. The rebound on the shock was a more linear curve which is great to see, however it was a little under valved again which will give it a loose unpredictable feel, instead of something more confidence inspiring.

We disassembled the shock and again inspected everything to make sure it was still original. Quite often if the shock it already modified it may change the work needed to get a more desirable feel.

Disambled Shock

The shock was all standard and again all in good condition. We decided to not only revalve the shock, but change the piston, the shock shaft and also install a floating piston to properly separate the oil from the gas. 

New Shaft

Shaft Adjuster

The shaft is something we make in house. There are two main reasons for changing it. Not only does the rebound adjuster inside it give a much larger range of adjustment, the internal oil galleries in the shaft flow much better. The better flow allows a more consistent control of how the oil flows through the piston and valving. 

Floating Piston

Piston In Body

This is where the piston will roughly sit in the shock body.

We fitted the new shaft piston and valving set up and got it ready for the dyno again.

Dyno KLR650

We do multiple runs at different speeds, different adjuster settings as well as ensure the shock is at a realistic operating temperature, so the viscosity of the oil is more like it would be under use.  This time the modification and valving did get the exact results we were looking for.

Dyno Sheet

This is the before and after low speed graph showing the difference.  If you have never seen a suspension dyno sheet before they measure the force required to move the shock a set distance at a increasing speed. Looking at the red line you can see that it takes close to 80kgs of force to compress the shaft 50mm at 160mm per second.  The minus side of the sheet is the pulling force required. Which is of course for rebound.

So what does it mean?

The blue line is the factory set up. You can see in the early stages it takes more force to compress the shock slowly. Then the force doesn’t really change through mid speed, but eventually is much softer as the speed is increased (could be being cause by aeration). It only takes about 55kgs to compress the shock over the same 50mm at the 160mm per second. So on the dyno it shows for faster impacts its about  45% stiffer.