I may see about taking the rockercover off at some point and just taking a look, see if i can clearly see a problem in there. It's a very definite tick, increases with revs, doesn't go away at any rev range, although i'm not going to rev it too high, if it drops a valve the engines buggered. I can't pinpoint if it's coming from a particular cylinder, I can't actually hear the tick through a screwdriver at all, literally no ticking sound whatsoever, just the hum of the engine and clutch noise. It does however seem noisier on the right side, it could possibly be that the cam chain blade/guides have worn so much that the tensioner is no longer able to push the blade into the cam chain itself and isn't tensioning. Anymore suggestions greatly appreciated.