Hi to all, I am a newbie to this forum so please be gentle!!

I currently have 5 Yams including a 2011 XT660X, and this is my third XT660, I luv em!! When I bought this one last summer it behaved perfectly for the first 4000 km and I really loved it, and I even told my dealer how much improved the engine management felt over my 2 previous ones (07 and 08). I had previously assumed that the surging was standard for a big single.......

BUT I recently noticed how poor the new one had become and it felt almost worse than the older ones had ever felt, surging all over the place and really tricky to ride in traffic! The flexibility had gone to pot and it would not cleanly pull 5th below 110 kph!! So I changed the spark plug which had very little effect, and then having read your forum I took the CO up by 10 points.

AMAZING!!! The bike will now pull top cleanly from 75kph like it used to, and has returned to being as sweet as it ever was. Thanks guys!! Simon