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KLR 600 A damaged cylinder head , still usable?

3K views 8 replies 3 participants last post by  klr600 
#1 · (Edited)
Hello everyone, would you consider keeping this cylinder head or is changing it definitely needed due to danger of further pieces breaking away? Would it make a difference if the broken piece would be grinded down or cut so that there is a lower chance of a part breaking off (now there is these couple milimeters portruding on top, not sure how to explain)?

There were no small pieces of metal in the head itself, its only scraped. There was metal in the small mesh filter by the clutch and a small piece floating around outside but there seems to be no other damage in the right part of the engine.

Top was opened for changing valve seals, this was a surprise - probably happened a long time ago and the engine continued to run ok.

https://www.imgur.com/PkSL6d0
https://www.imgur.com/HzJSAPM
https://www.imgur.com/Hqxn6pk
 
#3 ·
It looks like a mess to me as well but not sure exactly what you mean..

Btw the engine ran fine and there is no visible damage on the camshafts or cups and shims. Im thinking maybe the previous owner changed the camshaft due to damage and left the head like this? But then again the metal in the filter seems to be from this issue.
 
#6 ·
At the very least you need a new exhaust camshaft. The damage has been caused by the KACR coming loose. On an electric-start bike you could get by with removing the KACR, but I wouldn't recommend it on a kick-started bike. The KACR is the automatic compression release. Without it, rather hard to kick over.



The damage to the head is a bit more complex. If there are enough threads left that the valve cover bolt can hold the valve cover in place, fine, put it back and ride on. If the valve cover leaks from that corner you'll probably need to get some work done on it to repair the threads. I'm not sure if you could fix it with an epoxy product or if it would need welding, drilling, and tapping.
 
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#7 ·
At the very least you need a new exhaust camshaft. The damage has been caused by the KACR coming loose. On an electric-start bike you could get by with removing the KACR, but I wouldn't recommend it on a kick-started bike. The KACR is the automatic compression release. Without it, rather hard to kick over.

The damage to the head is a bit more complex. If there are enough threads left that the valve cover bolt can hold the valve cover in place, fine, put it back and ride on. If the valve cover leaks from that corner you'll probably need to get some work done on it to repair the threads. I'm not sure if you could fix it with an epoxy product or if it would need welding, drilling, and tapping.
I took some photos of the camshaft, I cant see any such damage, unless im missing something:

https://imgur.com/a/8dysFTP

As i mentioned earlier I am thinking maybe it happened to the previous owner and he changed the camshaft and kept the head. The head wasnt leaking and the bolt that was in that place was a bit easier to unscrew than others but obviously did its job.

I thought the biggest risk would be the upper part of the thread for the bolt breaking apart further since it initially broke to leave such an irregular shape. If thats not the case thats good news.

The bike has an electric starter and a kick starter. I never used the kick-starter to be honest, tried when i got the bike and never got it to start like that.
 
#8 ·
If the KACR mechanism is secure and not sloppy and shows no indication of having hit the head then I think your theory is correct.

If the valve cover bolt is not over-torqued and has been working fine I see no reason why the threads in the head would come apart.
 
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