4:03 No wheelie just hard acceleration. I guess it's possible.

Assist:

https://www.youtube.com/watch?time_continue=9&v=hFkJGoJQGo4

Oh dear. I have a generic stabilizer on mine. Not the best, but it does tame down the handlebar shake a lot so I assume it will be helpful if this ever happens.

Hyper-Pro here. IDK if it's any better than the knockoffs but I have noticed my steering yank back on track a lot more often and more forcefully when I have it off the bike. Really only coming out of a wheelie. I've never had any shake wwhen both wheels were planted. Maybe a single jerk when hitting a rough spot in a corner. I really have not noticed that at all with the damper. That's the only way I know it works because it steers normally otherwise.

But the intelligentsia on both ZX14 forums all declare the bike does not need a damper ....

I have my GPR V4 off for a tune up now, dont feel safe without it.

Has my first yesterday after havin my 07 since 2010. Caught me off guard after going over some railroad tracks I have been over many times. I might just invest in a stabilizer now.

I like this old vid from Dunlop from back in the 70's "Wobble and Weave"

Wobble and Weave

I'm glad they got that sorted out pretty much by the time I got into bikes.

I don't understand the tank slapper. Me and my buds have ridden many thousands of miles, a great many of them like maniacs, pushing the limits of traction in curves, very high speeds (no numbers mentioned), etc, and not one tank slapper.

What cause it? Is it caused by an equipment problem?

* Last updated by: extrapolator on 9/30/2017 @ 11:40 PM *

Motorcycles, like most vehicles, resonate. Different parts of the bike resonate at different frequencies. As with all resonating, it's possible for different frequencies to "couple". One of the scariest things that can happen is an air plane ripping itself apart due to this effect.

It's an oscillation which can be caused by problems with the bike and/or road. Your bike is always in a state of tank slapping. The frquency is there,it's amplitude is usually insignifcant and unoticable. All it takes is a little bit of this (ruts in a road), or a little bit of that (worn tire), and that oscillation becomes what we all know of as a tank slapper.

So basically it could be a combination of many different factors, one tank slapper may be a result of the front wheels contact with the road. Another might be worn suspension. Another might be a rider goofing around and shifting weight on the bike suddenly.

My first bike had been tweaked somehow. I really don't remember the details but I had a video quality tank slapper with it one time when I was fooling around and let go of the bars. It seems like one time with my 14 with probably very worn tires I had a very minor increase in amplitude (noticable) but nothing scary.

I always thought the main cause of a full on tank slapper was having the front wheel suddenly and radically get out of line withe back wheel. This seems most likely to happen when the front looses contact with the road and the steering is turned. It snaps back on track so violently that it gets sent over to the other side and the reaction repeats. It seems like it should loose momentum even if the motorcycle maintains the same speed but apparently it does sometimes increase even if you slow down. I've never experienced it either. If my steering is turned a bit, it has always seemed to snap back on track in a single motion after the front touches down and that's as far as it goes. The bikes with a steeper rake and shorter wheelbase are more likely to do it, I guess.

It's an oscillation which can be caused by problems with the bike and/or road. Your bike is always in a state of tank slapping. The frequency is there,it's amplitude is usually insignificant and unnoticeable. All it takes is a little bit of this (ruts in a road), or a little bit of that (worn tire), and that oscillation becomes what we all know of as a tank slapper.

Pretty close Vic

The structural resonance of the front of the bike is designed to be significantly above input disturbance frequencies from the road/wind dynamic's during the ride. From the vid you can see the slapper is responding at ~10 Hz (im guessing). KHI structural engineers would have dynamic profiles of the typical road conditions and would design the front end to be above the input frequency. Example: typical road input has frequency content from 4-12 Hz 1 sigma, therefore front end structure resonance shall be greater than ~30 Hz (making up loads and reqts here for example). So what could have cause the slapper example in the vid? Input above the design capability or front end resonance changed/reduced to now have much lower resonance frequency in band with input road noise.

All together now -- Service and Adjust Stem Bearings per the Service Manual!!

This maintenance will help the keep the front structure stiff and within the design capabilities minimizing the potential tank slappers. But it can't keep all of them from happening. Just because it hasn't happened to you yet doesn't mean it ever will or it could happen Tue on the next ride. Its dependent on the conditions. This is where the damper comes in. When the inputs try to excite the front resonance the damper limits them. This is why some events, track days or LSR require a damper on all bikes because under those more extreme conditions the probability of a tank slapper is higher than your Sunday ride with the group.

Apologize in advance for the techno geek out

* Last updated by: cruderudy on 10/1/2017 @ 10:49 AM *

My example...1972 H2 , full Denco kit, with spoke rear wheel. Rapid acceleration thru the gears and upon reaching 130 miles an hr and a shift point ( from drag racing many times, I know I was at 130 when preparing to change gears.,I made the shift and immediately went into a violent side to side TS. The front wheel made two almost complete direction changes and on the third one I stepped backwards off the bike. .After a few days I was able to inspect the bike . When I stepped off the bike, it was almost completely on its' leftside and it slid 97 yds in that position . ( I could see it in front of me everytime a made a complete roll:) But back to point. The rear wheel spokes were loose. I had been drag racing all summer and had never once checked spoke tension. My supposition was that during the shift, the front wheel became light, making it more susceptible to teh oscillations from the rear caused by the new force applied to the wheel by shift change.

The guilty party..altho I did have gloves on the day I crashed.

* Last updated by: chrly on 10/1/2017 @ 1:22 PM *

All together now -- Service and Adjust Stem Bearings per the Service Manual!

My supposition was that during the shift, the front wheel became light, making it more susceptible to teh oscillations from the rear caused by the new force applied to the wheel by shift change.

I can't find a video showing just this example but I'm sure we've all seen Isle of Mann videos where they jump or wheelie and the rear of the bike wiggles like a wet dog shaking his ass. That's probably something like you're describing. Never felt that sensation but it sure looks cool! --As long as the front stays straight, that is.

LOL..."I can't find a video showing just this example but I'm sure we've all seen Isle of Mann videos where they jump or wheelie and the rear of the bike wiggles like a wet dog shaking his ass. That's probably something like you're describing. Never felt that sensation but it sure looks cool! --As long as the front stays straight, that is."

Rook from my perspective , I never want to look cool again !! it took 2 hrs for nurse to dig the gravel/asphalt out and about a month for the skin to grow back

Rudy the same oscillatiuon that is the ever present "micro" tank slapping is also why all of our tires, given enough time, experience cupping.

And uh well...keep this in mind. If what you're saying is accurate (and I'm sure it is...I'm sure today's engineers do account for such things) you change tires, springs, oil, tire pressure, anything, and you're going to alter those frequencies.

* Last updated by: VicThing on 10/2/2017 @ 5:04 PM *

You're completely right Vic, but the 1st fundamental or resonant frequency will only move up or down a small bit, most of the resonance is determined by the rigid structure.

It's not my argument. The only rigid structure is the frame. Like I said, worn suspension parts can cause/contribute to the issue as well. However, your positing that it's impossible for a bike in perfect condition to experience a tank slapper and I'm telling you that's not the case.

Sorry about that, I'm agreeing with you. New bike or old bike, if you excite the rotational 1st harmonic with broadband noise at a level sufficient to overcome the inertia of that axis, that bitch is gonna slap you. But not with a GPR V4 installed

* Last updated by: cruderudy on 10/3/2017 @ 6:50 PM *

Been there done that. Bought a steering damper soon after.

Either induced by the rapid twisting of my right wrist and maybe a little by the thick chick on the back of the bike.

But, I have a GPR now.