The stock lever or spring is prone to breakage. Yes the 08's are better, but there have been some documented cases of the lever already breaking on those, and the spring is still the same spring used in the earlier models, which again, is prone to breaking. The reason for the spring breaking is at the factory, the end that is wound to make an attachment point has a sharp bend, causing a stress point on the spring. The Eagle Mike aftermarket spring does not have this sharp bend, but a uniform curve. The doohickey from the earlier models is made from two pieces that are tack welded together. Their quality is sub par. Alot of times the doohickey won't work is because of when the owner of the bike adjusts the doohickey at each oil change, they are not using a torque wrench and over tightening the adjustment bolt. This excess pressure pushes the collar of the bolt up against the face of the lever, causing a dimple or impression and also creating a curvature to the face of the lever, therefore reducing its ability to slide back and forth to create tension on the chain. The adjustment bolt should not be tightened more than around 60 INCH pounds for an OEM and 72 INCH pounds for the Eagle Mike's lever. The reason for engine failure from a failed doohickey is that the internal chain becomes loose and if revving or bouncing around hard from riding, the chain can jump time allowing the valves to come into contact with the piston and therefore causing major damage to the engine. Hope this helps some.. Just do a google on KLR650 Doohickey and you will get a few days worth of reading. If your's has not been changed, it is worth doing it, to have peace of mind knowing that won't ever be a problem furthe on down the road.