It's only happened twice, under the same conditions. When in first gear, givin her hell up to 14k, right when I let off the front end starts to shake, and its a loud tat-tat-tat-tat-tat-tat. When I bought the bike I notice a few scratches on the front left rotor, they are near the edge. I'm not total sure but I think that after each event more are appearing.I just took the left caliper to check, I didn't see anything. I notice that one of the pads is worn more then the other. It's very scary, could my caliper be catching my rotor? If it was I think I would have seen signs on the pads (cracks or scraps on the bottom of the pad). the rotor looks straight, everything eles look right. I am alittle low on fluid, could that make space for my pads for "flap" aroundand catch? I think It weird that the pads are only held it place by the top pins. I really need some help. Im friends that work at a bike shop dont have any answers. please if you have any ideas or have had similair problems let my know.

thanks

john

 

At what point does it quit tat-tat and shaking? You said twice under the same conditions. Those conditions were giving it hell in 1stto redline. That generally causes the front wheel to lift andhover. If that happens it often can cause a tank slap which could be what your describing.

 

It starts right when I let off the throttle, andit lasts for several seconds (3ish). Its not the speed, cuz I have been drive as fast and fasterin high gears (lower rpm)I don't see how it could be from a small wheelie. Can you explain this "tank slaping"/

 

tank slapping occurs when the front wheel begins a "back and forth" motion, as if you were sitting on the bike and wiggling the bars from right to left very quickly. it happens often going from a hard acceleration to a slow down, because the front end gets light in a hard accel. if it reconnects with the pavement and is not completely straight, it can cause a tank slapper... VERY dangerous, EXTREMELY difficult to recover from, and usually ending in a high-side of sorts.

although i don;t doubt that your front end is getting a little light under these extreme conditions, i don't think its a tank slapper. it could very well be a warped rotor... just because it "looks" straight doesn't mean that it is, rotors are highly precise parts, and a slight imbalance could cause something like that to happen.

it could also be a bad bearing in you head tube (not sure the technical term) if you suddenly close the throttle at 14k in 1st gear, its going to cause you to engine break pretty hard, putting strain on the bearings in your headset, if they are not seated correctly, or have worn a bit, it can cause a similar situation.

 

does your tank slaper sound like a tat-tat-tat....................
so, if its a tank slaper, I could do a few test runs and see if a can push her alittle bit softer up to 14k (softer enough where there isn't any wheelies) it see the conditions that the "event" can occur.

 

it should only make that sound if it about as bad as it gets, with the bars locking out to both side

 

the bar in hardly moving side to side, just shaking.

 

its not tank slapping, if yo encountered this most likely 5-10 times you would have gone down, its bad.

this is a extreme case cuz of speed but exactly what it is

http://www.youtube.com/watch?v=xUBwCX_Mv2Q