TOPIC:

Well, First off let me say that the ride i went on last night was crazy as hell. Me and my dad got the bikes out of the garage and went on our first long ride of the summer. We left at about 2 AM and didnt get back till about 4:30. Drove all over town. I rode my bike the hardest and fastest i have ever since i bought it on this ride. (anyone familiar with Sgt. Bluff or old highway 141 in Sioux City) theres a 2 laned stretch in between Sgt. Bluff, and 141 with big fields on both sides and goes as far as the eye can see. I decided to go fast and my dad let me lead so.. after dumping the tranny down 2 gears his headlight quickly became a small spec in my rearview mirror. Was easily rolling a good 100 mph. Let off the gas and let my dad lead again. We got back into Morningside and decided to hop on the interstate and head home. I got into North Sioux City and the interstate becomes 3 laned there for a bit. Nobody else on the road I thought "Eh, why not". Once again, Downshift, Throttle open wide, Lye down on the gas tank. Was in fifth gear with the speedometer buried around 5500 RPM. Brought it up to redline and passed my dad (who was going 75 easily) like he was sitting on the side of the road. That Kerker 4-1 is good for scaring the hell out of people when you shoot past them
My dad said he crapped himself when i blurred by. I topped my bike out (for my standards with poor valve adjustments) Had it at 8500 Which is redline. Im guessing i was doing at least 115-120. Please note, i never do stuff like this. I hate risking my left let alone other peoples lives too. Anyways, i got kinda scared. The wind rushing by was louder than my engine at redline with the header. I dropped the throttle shut and my front end dropped as well. Guess what came next.... A high speed wobble. Totally watched my life pass by, couldnt breathe, eyes wide open, heart stopped in terror. So what'd i do? I RIPPED THAT BASTARD WIDE OPEN AND BROUGHT IT PAST 9500 on the Tach. I kinda owe my life to my Mechanic in Moville. He told me the only way to get out of a wobble is to accelerate as fast as you can. My 81' KZ1000 straightened right up and rather than letting go of the gas, i just pulled in the clutch and rolled to a stop at the exit. I know stuff like this has probably happened to plenty of others on here but damn... Figured i would share this with you guys. Never topped out my KZ before so this was my first experience in that area. Hope you all liked the story.

You have now entered the Twilight Zone for Zed riders.

Those knee slapping high speed wobbles will get your attention. Roy

Kitten Tooth wrote: Well, First off let me say that the ride i went on last night was crazy as hell. Me and my dad got the bikes out of the garage and went on our first long ride of the summer. We left at about 2 AM and didnt get back till about 4:30. Drove all over town. I rode my bike the hardest and fastest i have ever since i bought it on this ride. (anyone familiar with Sgt. Bluff or old highway 141 in Sioux City) theres a 2 laned stretch in between Sgt. Bluff, and 141 with big fields on both sides and goes as far as the eye can see. I decided to go fast and my dad let me lead so..

Some facts that cant be ignored

National Highway Traffic Safety Administration (NHTSA); a study recently conducted on motorcycle accidents and safety

Here's a summary of National highway traffic reports
Single vehicle motorcycle crashes account for about 45 percent of all motorcyclist fatalities. The report claims to provide data for insight into possible causes for these fatalities.

According to the report, (ten year period) there were a total of 11,038 fatal single vehicle motorcycle crashes. (I've chopped out quite a bit)

Report Conclusions: Findings from the FARS (Fatality Analysis Reporting System) data illustrate possible reasons for motorcyclist fatalities in single vehicle motorcycle crashes:

Helmet use among fatally injured motorcyclists below 50 percent

More motorcyclist fatalities are occurring on rural roads

High blood alcohol levels are a major problem among motorcycle operators

Half of the fatalities are related to negotiating a curve prior to the crash (speed)

Over 80 percent of the fatalities occur off roadway (speed- lost control)

Undivided roadways account for a majority of the fatalities

Almost two thirds of the fatalities were associated with speeding as an operator contributing factor in the crash

Almost 60 percent of motorcyclist fatalities occur at night

Collision with a fixed object is a significant factor in over half of the fatalities

Braking and steering maneuvers possibly contribute for almost 25 percent of the fatalities That would be tank slap/wobbles too

Almost one third of the fatally injured operators did not have a proper license

What this NHSA report hinted at was that most motorcycle fatalities had little to do with getting hit by a car.

We're all glad you got lucky.
How many items on the check list you had going for ya?
I've heard anything from let go the handle bars, to 'ride it out'. My only wobbles were low speed.
Life is fragile.

Might want to keep the fun to blast of speed up to 3rd gear. Watch out for DEER, thats our biggest problem by me

Pucker factor 9.9 Those tank slappers will make ya crap your pants. Reminds me of some of my adventures.

You just earned some respect for the Z didn't ya.

Hey KT, yeah a tankslapper will wake you up.

I had a 100mph getoff from a tankslapper about 20 years ago. I was lucky to walk away from it, though not unscathed. My knees were ground down to the knee caps. The entire face and chin guard of my helmet was ground down. That would have been my face if I wasn't wearing a full-face helmet.

I did a lot of research into tankslappers after that. From reading a couple motorcycle constructor books I gathered that it is often caused by the back wheel, specifically the back tire. The wider the tire, the worse the problem. But the biggest factor for the tire is if it was worn down. The flat surface of a worn rear tire leads to tankslapper. After repairing the bike and replacing the rear tire (which was very worn) I haven't had the tankslapper recur. I replace the tires very regularly now.

Often, slowing down quickly during a tankslapper makes it worse. This is because the front end lowers and the steering angle steepens. That's why speed testing a bike should be done very gradually, so backing off quickly won't be necessary. When I was in the middle of the tankslapper, I had already accelerated so quickly into the speed of the tankslapper, I couldn't back out of it gradually. If I hadn't accelerated so quickly, I may have only had a minor wobble that I could have backed out of. By the time I thought of doing anything, I was already on the ground. The bike just shoots out from under you like it was attached to a brick wall by a cable.

Another exacerbating factor is weight on the handle bars. Tankslapper is a resonating oscillation. This means it happens because the frequency of the handlebars swinging back and forth matches the frequency of the rear (or front) wheel wobble. By reducing the weight (actually the rotational inertia) of the front, the idea is to get the frequency of the front higher than the highest speed obtainable by the bike.

I think a common mistake people make when first putting a bike back on the road is that they concentrate too much on the motor, when they should really be concentrating on the chassis... tires and wheels and brakes, then followed closely by steering bearings, swingarm bearings, fork seals and bushings, and rear shocks, plus any misalignment corrections from previous crashes etc. After the chassis is solid, then work on the motor.

A steering damper will reduce the severity of tankslapper slightly, but that is not what is designed for. Even so, I added them later to all of my bikes, just for a piece of mind, plus it does reduce the headshake from bumpy roads etc.

I'm really glad you're ok! Speed wobbles can be caused by a number of factors; I list some below. I suggest you try very hard to find the cause because if it happens again you may not be so lucky (for example if you were braking because of an obstacle you would not be able to speed back up). The following items should be checked to ensure they are in good shape:

Tires - even tires that look good may create a problem (this happened to me - speed wobbles at 90+ mph). Make sure the tires have plenty of tread life left, are properly inflated, balanced, and properly seated on the rim (check the lines around the bead to be sure they are consistent with the rim).

Steering stem bearings - make sure they are not too loose or tight, if they feel at all notchy when turning the handlebars replace them (I highly recommend tapered roller bearings).

Swingarm bushings/bearings - These should have zero detectable play. Unhook shocks and from the very back end see if you can twist the swingarm at all - if you can feel play replace the bushings or bearings.

Rear shocks - Worn shocks can cause serious handling issues - if your rear suspension has any pogo effect or twitchiness when going over uneven road surface (especially noticeable in turns) you should replace (or if possible rebuild) the shocks with quality units.

Front forks - Ensure the fork oil is fresh and of the correct weight for you bike. Use quality fork oil (I know, some folks use other fluids, but I don't recommend it. Fork oil is made specifically for forks so you know it works - other stuff may or may not, so why not just use the correct stuff). Measure the fork springs and see if they are withing the service limit as described in the Kawasaki Service Manual - if not, replace them. Your front forks should move up and down smoothly but should not be mushy.

Make sure your brake rotors run true, if they are warped replace them.

Make sure your rims run true, if they are bent replace them.

Also, keep in mind that because speed wobbles are caused by different factors there is no single way to recover from them that always works. In your case accelerating helped (this might indicate a front fork issue), but sometimes accelerating makes the wobble worse (as it did with the wobble I had). In any case please check out the various potential causes. I was lucky that in my case I could easily recreate the problem (although NOT fun) by speeding up to 90 mph because it happened every time, so once I found the problem I could test that my fix worked. I don't suggest you try that with the wobble you had because there's no good way to gently recreate it, so you could get hurt. Be careful. Ed

So that means theres something wrong with my bike then? hahaa im thinking that the head tube bearings for the triple tree need replaced. Theres a very slight amount of play in them.

If there is play the steering stem bearings may need to be replaced or maybe adjusted (use the manual for adjustment). I would also check the other items out and see if there are any other weaknesses. Sometimes a wobble is the result of several different items joining forces to work against you. I ended up replacing a bunch of things, each of which slightly reduced the wobble. The last thing I replaced were the tires (which really looked good) and Bingo - zero wobble at any speed. Replacing the other parts was not a waste of time or money, because in fact those items were not really up to snuff; otherwise replacing them would not have reduced the wobble even slightly. Ed

Some very good info contained in this thread.

Been there, done that.
Nothing like coming up on a red light doing a 100 and the only course of action to save yourself is to peg it

I'm glad your OK

Check it all,

JD