Some will probably remember that I had a problem with valve guides a few years ago. Well, in the process of repairing the damage and wear to the exhaust seats caused by *very* worn out valve guides the machine shop had to cut pretty far into the seat - it ended up nearly 1.5mm deeper than a new one. But there is still a huge amount of material underneath and, other than possible shrouding of the exhaust gasses causing a tiny loss in HP, there didn't seem to be anything wrong with doing that.

Well, after ~2K miles I checked the valves. Intakes were fine, but the exhaust valves have both receded 0.1mm - a lot! I re-shimmed them, and just recently rechecked after another ~2K miles - vertical head exhaust had tightened a little, but the horizontal head exhaust valve had dropper *another* 0.1mm!

Not sure what's going on here, but I'm past the limit of standard Ducati closer shims. So, rather than fight this in the motorcycle I just bought another set of heads off Ebay (valves, no other internals, 15K miles, $300.00 for the pair) and I'm going to clean them up and use them.

Later I hope to get to the bottom of why on earth these seats are going away like this.


Sam