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Sticking exhaust valve

4.1K views 8 replies 3 participants last post by  Krtek  
G
#1 ·
Need a bit of help here , at the weekend i fitted a new camshaft/bearings and cam followers to my xl600 rmg. I put it back together and it started on button and sounded as sweet as nut. However I used the bike to get to my work last night and on they way home this morning it started to rattle at bit, I did,nt waste any time and got it out of frame and removed rocker cover to investigate,It looks like that the exhaust valve on the decompressor side is not returning to it fully closed position it looks visibly more compressed than the others, The camshaft and folloewers that came out of the engine where very worn, any ideas how to get the valve back in it,s correct postion , any pointers would be a great help, please don,t say remove the head ,that just terrifies me:(
 
#4 ·
No cracks in the head? Then find your local engine specialist.
Can anyone recomend one in the Edinborough area?
They'll know if and how it can be sorted.
Don't think it's something you can do yourself, anyone?
 
#5 ·
Well, I had a valve seat come out (haven't we all) and put it back in, heating up the head in the oven, and then secured it in place by punching holes in the aluminium of the head right around the valve seat, pushing the metal out to form a tiny edge. It kept the seat in place for about 40.000 km.
As always, your mileage may vary... quite a lot.
 
G
#6 ·
you will probably not believe this but i have just done the almost indenticle repair you have described , the seat was by no means loose in its postion, I used a socket to force the seat back in to postion and used an automatic centre punch around the seat to expand metal, the bike is back together and running again, sounds spot on ,why would does the valve seat come loose ,any idea?
 
#7 ·
why would does the valve seat come loose ,any idea?
Because Honda made the heads of certain models/years out of ginger bread instead of aluminium, and it cracks over the years, which in turn allows for so much movement when heating up and cooling down that the valve seats drop out. Typically, it's one of the exhaust valves.
Oh, and of course, XLs tend to run hot. That's another big part of the problem. That's why I believe in adding an oil cooler, as part of the solution.
 
#8 ·
If you look at a typical 2 stroke air cooled ,the fin area is large,but with the xl600,to get the same fin area,the head would have to be the size of a portable telly.
Just had my head repaired and i am certainly going to look at fitting an oil cooler.
as the other member said,they are made of monkey metal,10% aluminium and 90% monkey s@@t