stability problem

I am having a stability problem when doing stand up wheelies. The back wheel progressively starts to track from side to side until I have to put the bike down for fear of a slapper. The longer the wheelie or the faster I go, the more the back starts to step out. Any wheelie over a quater mile or over 70mph starts to get uncontrollable. This has only been happening for the last couple of months. I checked the rear alignment hash marks and they are properly aligned. (I know these are only so accurate.) The rear tire has some miles on it, so it is somewhat squared off (no comments, the edges are thrashed, too;) ) but I can't see this being the cause. Tire pressure is good and every thing is tight-including chain. HELP! This sucks!:cryin

Nobody has any idea what this can be????????????????:confused:

how many miles are on the bike.......what kind of condition is the rear shock in?if you have alot of miles on the bike the rear shock could be squishy......and you may either need to redo it or replace it.on my old 93 zx-11 the rear shock was sacked out at 6000 miles......and i wasn't doing stand ups,sitdowns or anything out of line with it. ihave read on other web sites that yamaha skimped on the quality of the suspension to give us the chassis and engine while keeping th price inline....... as for your tires...they are not helping stability one bit,and with the hash marks for alignment.....do it another more accurate way hope this might give you some insight......

is it windy when you pull it up? I too sometimes get wobble when I pull the bike up for a standup. Are you high enough? It could also be your rear wheel bearings that are beginning to wear out. Replace them. Tighten up the rear shock just incase Prowler her is right. Could help a little.

Thanks for the input, guys. Prowler, I think it might be the rear shock. I checked the rear ride height against my other R1, and it's sitting about 3 inches lower in the back! The bike has about 6k on it, but I stand-up and stoppie the life out of it. I also weigh about 230. I'll replace it and see what happens. Regarding the wind, I compensate for it if it's bad. Either lean, or not wheelie altogether. It swirves regardless of hpw much wind their is. My wheelie height is fine. I hit the balance point and don't speed up at all. The bearings may be shot. I'll replace those, too. Thanks again guys!! :jump

My tyres were both quite worn but appeared to have their profile still. Rear was actually slightly more worn on the edges than the middle (with just road roading :finger ) and the bike was a nightmare for twitching about - felt terrible. New set of D207RRs and it's like riding a completely different bike. Obviously tired old suspension messes things up but it surprised me just how bad it was given that the profile still seemed to be there. The Fireblade I had previously wasn't nearly as sensitive.

just try and squezze your knees agianst the tank. it hep me a lot with the same problem.