NHTSA Complaint #10399440 — 1999 KAWASAKI KLR650

THE 1986-2007 KAWASAKI KLR650 MOTORCYCLE'S TENSIONING SYSTEM FOR THE ENGINE BALANCER SHAFT DRIVE CHAIN IS UNRELIABLE, AND A FAILURE COULD LEAD TO SUDDEN ENGINE LOCK-UP AND LOSS OF VEHICLE CONTROL, POTENTIALLY RESULTING IN INJURY OR FATALITY. THE MOST TROUBLESOME PARTS OF THE BALANCER DRIVE ADJUSTING SYSTEM ARE THE IDLER SHAFT LEVER, P/N 13168-1436 AND THE SPRING, 92144-1860. THE BALANCER ADJUSTER IDLER RIDES ON AN ECCENTRIC SHAFT P/N 39115-1077, AND WHEN THE SHAFT ROTATES IT CHANGES HOW THE TENSION IDLER RELATES TO THE BALANCER CHAIN, ALLOWING THE CHAIN TO BE TENSIONED. THE RECOMMENDED PROCEDURE FOR ADJUSTMENT IS FOR THE USER TO LOOSEN A SCREW THAT HOLDS THE IDLER SHAFT LEVER, ALLOW THE SPRING TO PULL THE IDLER INTO ITS NEW POSITION, AND THEN RETIGHTEN THE SCREW. IF THE IDLER SHAFT LEVER FAILS THE SPRING IS INADEQUATE TO WITHSTAND THE CYCLIC LOADING AS THE CHAIN RUNS AT ENGINE SPEED, AND WILL LEAD TO FAILURE OF THE SPRING AND LOSS OF TENSION IN THE CHAIN. IF THE SPRING FAILS BETWEEN SERVICE INTERVALS BUT THE SYSTEM WAS PROPERLY TENSIONED TO BEGIN WITH, THE CHAIN WILL LOSE TENSION WHEN THE USER LOOSENS THE ADJUSTING SCREW. ALSO ON HIGHER MILEAGE VEHICLES THE SPRING CAN COME OFF ITS ATTACHING POINTS AS IT BECOMES TOO LONG FOR THE APPLICATION, CAUSING IT TO FALL INTO THE ENGINE. IN EITHER CASE THE FAILURE CAN RESULT IN THE BALANCER DRIVE CHAIN BECOMING EFFECTIVELY UNTENSIONED. THE CHAIN IS FREE TO COME OFF ITS SPROCKETS, OR TO BUNCH UP AROUND THE CRANKSHAFT SPROCKET THAT DRIVES IT, OR TO SOMETIMES CATCH ON THE DRIVE SPROCKET AND SOMETIMES SLIP LEADING TO RAPID SPROCKET AND CHAIN WEAR CREATING METAL DEBRIS INSIDE THE ENGINE. IF THE CHAIN BECOMES BUNCHED UP AROUND THE CRANKSHAFT SPROCKET IT COULD LOCK UP THE ENGINE AND MAKE THE VEHICLE SUDDENLY IMMOBILE AND UNCONTROLLABLE. *TR