I searched quite a bit but couldn't find anything so I was hoping one of you guys might have the answer to this. I just bought this bike (02 400s) so I don't know much about when any sort of services have been done but here is what I am experiencing. The bike has Kenda 270s on it when I rode it, I noticed the front end would start to shake when I got over 40MPH or so. It's not shaking like a head shake (side to side) but more like up and down (like I was holding a jackhammer). I noticed that these wheels have rim locks on them and there were no weights so I stuck the wheel on the balancing stand and got it balanced pretty good (not perfect but pretty close). The shake is still there after balancing. Between that and tightening the front suspension up a little, its better, but still starts to get pretty noticeable at about 50 MPH now and much worse as you speed up. I also stuck a dial indicator on the rim and spun it - it is straight as an arrow. To the eye, it seems like the tire itself has a bit of a wobble when i put the front end in the air and spin the tire but maybe my eyes are deceiving me. I don't feel any play in the neck bearings and the suspension doesn't seem sloppy so I'm thinking its the tires even though they look fairly new. If I thought for sure it was the tires I might have some different ones put on but I'm just not sure. Oh, and this is my first DS.