Originally Posted by Aidan
I think you should write to MD of Yamaha Europe advising that we are all waiting on he outcome here on he forum??????
This all happened over here in the Colonies Aidan, but I do have a pretty thick file from Yamaha Canada. Their responses baffled even the dealer (who, I should point out, was very helpful. The first powerhead that blew, he sold to me at his cost, and installed it for nothing as it was about 45 days past the warranty expiration).
Yamaha sent a factory mechanic in to examine the first one, and pronounced that the cylinder that failed had corrosion inside: "probable cause was failure to winterize properly, causing condensation". Ummm, doubt it... done by a different dealer, receipt provided. Yamaha's response to this was to ask if I had "retorqued the head bolts during break-in". WTF? Dealer new nothing of that. Nothing in the owners manual. Nothing in the service manual. Apparently, there was a "directive" issued somewhere along the way.
When the second one went, the mechanic (a Merc dealer) felt that the probable cause was a sticky check valve in the oil-injection line which either reduced oil flow or possible drained when the engine was off, causing a delay in lubrication to begin each time I started. Since this was a replacement head, it had come with a 30 day warranty (!) and so I didn't waste the effort talking to Yamaha.
I will say again, that otherwise the engine ran beautifully right up until the point(s) that went "bang/clang/stop"...!