Motorcycle Repair: 2000 honda xr100r, sprocket teeth, tension bolt

Question
Hey, Bill
I know this may not be your area of expertise, but I was hoping you might be able to give me some help. I have a 2000 honda xr100r which I recently had to replace the cam chain, cam sprocket and piston rings on due to cam chain slipping off the old sprocket and locking up/damage to sprocket. Now the new cam chain wants to rise up just alittle which causes a "Click" sound when it reseats on the sprocket teeth. Tensioner knob is adjusted with mark pointed to rear of motorcycle as instructed in Clymer. Someone told me this was normal on some Honda bikes, but I don't remember it before. Should I be concerned that this is why the old cam chain jumped off or was it simply due to wear and stretching.
thanks, rick

Answer
Rick, sounds like someone forgot to ever tension the camchain and it finally jumped off (or the lock bolt was left loose). You may want to look at the crankshaft sprocket, to determine if there is excessive wear or damage there, too.

Be sure that you have the correct camchain and sprocket set as there are some fine differences in the chain pitch some of the camchains. The chain should wrap around the sprockets snugly and not rise up the teeth. The only time the chain will get under pressure is when the cam is starting to open or close a valve. As the rockers engage and drop off the cam lobes there will be tension on one side of the chain or the other.

Be sure that the camchain tension is set correctly before you condemn anything there. If the chain is not tight, it will pop a little when the valves are going through their cycles, not when it is tensioned correctly.

Back off the tension bolt and turn the engine over so it is at TDC with both valves closed. Tighten the tensioner bolt and then turn the motor over and see if it is doing the same thing. DO check the sprocket to see if it has any damage or odd machine marks. They are relatively soft material and can be damaged easily if you aren't careful with the installation.

Bill Silver