I bought a 650 honda last year, it's used but in great shape, looks brand new. I love the suspension, it's great for my old back but the power just really sucks. I put 26" wheels and mudders on the thing when I bought it and I know that hurt theget up and gosome but both my wife's honda 450 and my little yamaha 250 will blow it off the trail. I,m suspecting something is wrong. I put a new spark plug in it and that didn't help. It doesn't smoke at all and starts easily. Anybody got any ideas, could the valves be that bad out of adjustment. I rode a friends yamaha the other day, 660 I think, and it's got the twice the power mine has.