So I recently purchased my 2006 KLR with 34,000 miles on it. I have a thread in the introductions section of this forum if you'd like more information. The previous owner didn't know the last time the valve clearances were checked, so recently I decided I should do that and fix the leaky valve cover at the same time
I should state up front while I am no engine expert, I am a fairly experienced mechanic but I am new to motorcycles and KLRs. I have done some light engine work before, and have helped assemble long block car engines as well. However I am no engine builder.
The intake valves were barely in spec so I anticipated ordering shims, the exhaust valves were not in need of adjustment. I removed the camshafts, and I was immediately disappointed at what I saw. Mind you, my phone doesn't take excellent pictures s(I tried to do the best I could).
As soon as I removed the VC, I saw that this piece of metal had been rattling around the top of the cylinder head. It was located on the intake side of the head. Is this a cam end cap? You can see me placing it at the end of the intake cam to visualize if that's where it's supposed to be. Are these cams supposed to fill with oil once under oil pressure? That was my first concern.
However that wasn't the worst thing. The head journals and some of the cam bearing caps looked (to me) awful in places. I've seen cams/valvetrains with many more miles that looked perfect, and clearly there is significant damage to the aluminum bearing surfaces (in varying degrees). Prior to discovering this, the engine seemed to be running well. No burning oil or awful sounds. Now that I know what it is, I think I might have heard the loose piece of metal rattling around the top of the head before I disassembled.
The original owner (not who I purchased the bike from) installed a 685 kit from Schnitz, and it's safe to assume something went very wrong to motivate buying the big bore kit. When I just finished replacing the clutch recently I found aluminum chunks (big pieces) in the oil screen that I can only assume were once a piston. I decided to read up on KLR engines a bit before starting this thread, so I am very aware if the engines are run low on oil the top end is the first thing to go. I'm thinking the original owner did this, somehow it blew up the piston, and damaged the journal surfaces enough to be bad but less than catastrophic.
I should state up front while I am no engine expert, I am a fairly experienced mechanic but I am new to motorcycles and KLRs. I have done some light engine work before, and have helped assemble long block car engines as well. However I am no engine builder.
The intake valves were barely in spec so I anticipated ordering shims, the exhaust valves were not in need of adjustment. I removed the camshafts, and I was immediately disappointed at what I saw. Mind you, my phone doesn't take excellent pictures s(I tried to do the best I could).




As soon as I removed the VC, I saw that this piece of metal had been rattling around the top of the cylinder head. It was located on the intake side of the head. Is this a cam end cap? You can see me placing it at the end of the intake cam to visualize if that's where it's supposed to be. Are these cams supposed to fill with oil once under oil pressure? That was my first concern.
However that wasn't the worst thing. The head journals and some of the cam bearing caps looked (to me) awful in places. I've seen cams/valvetrains with many more miles that looked perfect, and clearly there is significant damage to the aluminum bearing surfaces (in varying degrees). Prior to discovering this, the engine seemed to be running well. No burning oil or awful sounds. Now that I know what it is, I think I might have heard the loose piece of metal rattling around the top of the head before I disassembled.






The original owner (not who I purchased the bike from) installed a 685 kit from Schnitz, and it's safe to assume something went very wrong to motivate buying the big bore kit. When I just finished replacing the clutch recently I found aluminum chunks (big pieces) in the oil screen that I can only assume were once a piston. I decided to read up on KLR engines a bit before starting this thread, so I am very aware if the engines are run low on oil the top end is the first thing to go. I'm thinking the original owner did this, somehow it blew up the piston, and damaged the journal surfaces enough to be bad but less than catastrophic.