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Discussion Starter · #1 ·
Hey guys, I've been pounding on my '93 Katana 600 pretty hard lately and this just recently developed.

Whenever I let go off the handlebars, it will shake back and forth very quickly (tank-slapping action). It gets worse the faster I'm going and I can control it when I grip the bars, but this is very scary and annoying. What's going on here?
 

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Could possible be a coule things. 1) The steering head bearings could be loose. 2) the front wheel could be out of balance or bent 3) possible the rear wheel is not aligned with he front.

I had a friend of mine that I saw this happeneing to. He used ot do a lot of wheelies and land them hard. #1 is my best guess.

While holding the front brake. Rock the bike front ot back. The forks should compress smoothly. If you can feel some play in the front end, the bearings need to be tightened.
 

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Good answer Cherrypicker-- I agree with the head bearings loose.
Although you really did'nt define "pounding" to well crazeinc i assume you mean hard launch and stops.? If you are stuntin you may want to check answer #2. wheel bent or alignment ;)
 

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Also check to see if your front tire is cupped. This has caused me head shake in the past.
 

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These are all great ideas. Bottom line is a 600 kat should not be having tank slapper problems this badly. Something is wrong mechanically. My R1 doesn't have it that bad and I ride pretty hard without a damper.
 

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Discussion Starter · #6 ·
Yea, i was praticing stoppies last night and then I really noticed it. Thanks for the help guys, I'll check it out tonight.
 

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crazeinc said:
Yea, i was praticing stoppies last night and then I really noticed it. Thanks for the help guys, I'll check it out tonight.

Don't forget to take pics and do a how to when you change those bearings:D
 

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Discussion Starter · #8 ·
Alright, well either I'm not finding the proper place to tighten the bearings or the wheel is outta balance. I did the test to see if it was the bearings and I didn't really feel any play.

Fortunately, the front tire needs to be replaced anyway and the replacement is already waiting in my garage :cheers

Who does the best and cheapest job changing tires around here (I'm in Naperville)? I don't really need the back done now, but the front needs to be changed asap if it's causing this tank slapping problem. Is a balance normally included with a tire change?
 

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I usually have Craig at Naperville Motorsports (aka Triumph Suzuki) do it for me.

I don't know about the CHEAPEST and often that is not the best.

Editorial note: I will never understand why you folks stunt on a bike that has tires needing replaced or other mechanical problems, but hey, it's your neck!

You'd be amazed at the people doing endos on tires with the threads showing!:nono
 

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I use Craig too - Naperville (Suzuiki) is not the cheapest, but their prices (for service) pretty good. Their prices for parts are so so. They are almost always cheaper than Downers Grove (DGY).

Hey whats's cupping ?? :confused (probably a dumb question)

Bought some takeoffs the other day - total amount of tread wear didn't look bad at all, BUT some of the outside treads have a small curved up lip on them right at the edge. Hope I didn't just waste my money. The front looks pretty good - Craig is mounting it now & doing my brakes. The rear I am holding off on till ??

Thanks
 

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all good answers above, and just to add to the list, forks need to be serviced , if this has never been done , the oil in there is MUD !, also some shaken could be coming from the front bushings being worn. :D
 

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crazeinc said:
Alright, well either I'm not finding the proper place to tighten the bearings or the wheel is outta balance. I did the test to see if it was the bearings and I didn't really feel any play.

Fortunately, the front tire needs to be replaced anyway and the replacement is already waiting in my garage :cheers

Who does the best and cheapest job changing tires around here (I'm in Naperville)? I don't really need the back done now, but the front needs to be changed asap if it's causing this tank slapping problem. Is a balance normally included with a tire change?
Most of us use Dano5150. He's on the board. PM him he works at Woodfield motorsports. it's a bit of a drive but $23 a tire.:thumbsup
 

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selston said:
Hey whats's cupping ?? :confused (probably a dumb question)
Cupping is an uneven wear pattern on the tire such that the tire can oscillate. It is most likely caused by an out-of-balance tire, under inflation, or too much weight on the bars. The wear is such that for any given circumference of the tire thread, the thickness of the tire tread shows a varying wear pattern.
 

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Put air in your front tire. Its sound like your tire is starting to cup. Meaning uneven wear. If you're running low pressure it'll cause the bars to shake like you're saying. If the tire not too bad just adding air (38psi or so) should solve it. If it doesn't, replace the tire.
 

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Discussion Starter · #15 ·
$23 a tire...Now we're talking!

Do I have to bring the wheel already unattached, or does that price include everything?

Thanks.
 

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crazeinc said:
Do I have to bring the wheel already unattached, or does that price include everything?
$23/tire is the price with the wheels off. If you just ride the bike in, it's $45 per still, as far as I know.
 

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Cupping is wear primarily caused by braking and also just rolling resistance. It's made worse by underinflation and by poor suspension action or bottoming of the forks.

Imagine you're the contact patch of the tire... the bike is hard on the brakes. There is a haevy load puching into the pavement squishing the tire flat against the pavement. At the same time the torque generated by applying the brakes causes the tire to grab against the pavement. The leading edge of the trad pattern, digs in harder than the trailing edge and the center part of the tire has the greatest load and and digs in harder. The result is the tire wears away unevenly and carves out little waves in the tire.
 

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Bought some takeoffs the other day - total amount of tread wear didn't look bad at all, BUT some of the outside treads have a small curved up lip on them right at the edge
Hey Samuel....

I believe what you are describing is just the wear from when I first started to really lean the bike over on the track...there's a lot of good rubber left on those 207s.

Are we going to see you at Putnam?
 

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cherrypicker said:
The leading edge of the trad pattern, digs in harder than the trailing edge and the center part of the tire has the greatest load and and digs in harder. The result is the tire wears away unevenly and carves out little waves in the tire.
OK - this seems to describe the condition of the takeoff. But it is a rear tire ! (pressume same can happen due to accelleration forces !?).

So do I mount the tire & use it anyway - its got a fair amount of tread left. Or do I toss it ??

Thanks for the info guys
 
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