Flashback wrote:
In most cases, piston slap happens when the engine is cold..as it warms up, the slap will disappear........
Flashback, that's exactly what I've been thinking!
In fact, every explanation I've ever been given on R* knock/ping/slap/clatter is counter-intuitive, because the clearances should all get smaller when warm, not bigger. I simply do not buy the oil thinning story Yamaha puts out. Were that the case, I would notice a big difference with different viscosity...but i don't. As I've said here before (too many times lol) nothing has changed the basic character of my '07, which is that it sounds utterly beautiful, like a blue printed hot rod, for about 15 minutes. Then it sounds like it's about to break a piston or throw a rod under a light load. But it runs fantastic when I get on it!
Very fast right now, and I still haven't ported the manifold! It sounds GREAT wide open, and it sounds great at anything less than about 1/16th throttle. But just when I'm having fun with it, I'll need to accelerate gently in traffic, and there's that knock
So, it's a mix of good and not so good. I love the bike, but I do wish it would shut up a bit.
Favoured: 0
Synthetic oil, iridium plugs, and hit the limiter will keep it running good. 
pre-detonation (spark knock) is probably the most common, and can be related to a lot of different situations. Carbon build-up is usually the cause unless an ignition part is failing. I would start with insuring that the combustion chambers and valves are cleaned up first and then go from there if needed...my .00002.......
