Hi Guys
I`ve been riding my bike a far bit lately and i have found i am getting a lot of tank slap.
I thought it might of been fork oil levels but i rebuilt the forks and it is still there. What could be it be from?
I have a steering dampener on the way and a set of allballs steering head bearings so i can tighten the head stock a bit.
Will these fix the problem or could it be something else
Any ideas would be great as i have a track day in december and i want to sort it out.

I hate the feel of a steering damper on an NSR. But thats me.

I let mine slap, yup it's thrown me off a couple of times but its feels much nimbler without.
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If I have to take the carbs off once more...

Mine MC28 doesn't slap at all... And that's because it hasn't the power to do it...!!!! (at the present...!!!)

Both my MC21s are without steering damper. Both slap a bit when they are being pushed but I don't mind it. My RGV used to tank slap a lot (as far as I can remember, or maybe I just rode that harder - joys of youth).

If you want to dial out tank slapping completely on your NSR, best advise is to probably get a different bike (ie not a sports 250)
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

I've no real choice,but to use a damper,given the state of the road network around here!However Dunlop Alpha10s are really stable,and I've been able to turn the damper down to two clicks from five!I had been using Bridgestone 090s.

My 21's always been stable, but the front was absolutely glued to the tarmac with the (short) RWU NF5 forks. There's a long sweeping uphill curve near Steve's though, that it just won't take flat out... didn't like it with SP suspension, and didn't like it with NF5 RWU's. I can't recall riding there with the NF5 USD forks though, but I'd probably have a mental block on that corner now anyway, and will instinctively roll off a little when I go through it. Strangely Steve's MC18 slap happy chappy seemed to go through there without any problems! If his MC21 slaps though, that's understandable with the power it makes!

I've never run a steering damper, and I now run later NF5 forks (and an HRC shock) and the handling is wonderful. If your rear shock is buggered/on the way out then that can cause it to slap. Just because the front's wobbly, don't just assume it's the forks. I wouldn't advocate over-tightening the head bearings either. It's not a cure.

It's strange, as the MC21 has a shorter wheelbase than the MC18, and significantly shorter wheelbase than the RGV (by about 40mm ), yet is much more stable than both. Better chassis design.

mixalisen wrote:
Mine MC28 doesn't slap at all... And that's because it hasn't the power to do it...!!!! (at the present...!!!)

The problem there Michael, is once you have the power, you have that rubber swingarm to contend with!
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Andy.
NSR-WORLD.COM

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How old are the tyres?

Are they the right pressure?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
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mixalisen wrote:Mine MC28 doesn't slap at all... And that's because it hasn't the power to do it...!!!! (at the present...!!!)

Hurry up with the modifications mister...

My R2J will -hopefully- be ready before the new riding season starts and then you ll see why, dropping all that cash into that beautiful, but slow bike of yours, is dead wrong...



Back on track now. I can't get used to the feel of steering dampers on my 21.

I tried WP and Ohlins but still...

Tyres with a triangular profile will naturally produce more 'slap'....

But for a track day, as the original post alluded to, giving an NSR some beans will produce some tank slap, at some point around a track.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

how old or new are the head stem bearings? Have you raised or lowered your forks through the triples as well?

Definition of HARDCORE;

StephenRC45 wrote:I let mine slap, yup it's thrown me off a couple of times but its feels much nimbler without.

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After years of moaning about immigrants now i am one...

Front tyre is new dunlop. will be getting new rear next week .
Havn`t droped front forks will that help?
It Is fairly bad overtook a few cars the other day and hit 140-150kmph and it was lock to lock no fun but just hitting a small bump in road will give it a bit of slap just seams to do it to much.
Thanks for all your reply`s

I know you said new tire already, but my tank slapping always began when the tire was worn. So, next I'd try to adjust it out. Assuming the forks are healthy, personally I'd try to increase the preload so the rake gets a bit lazier. If you can get the back of the bike down, or the front a bit higher I think things would go away. The steeper the rake, the more propensity to be upset into slapping. Seem reasonable?

RZ Rob

When you get a tank slap , NEVER roll off the throttle . It upsets the balance of the bike , keep it pinned and your bike will settle down .
I have found that when i put more body weight over the front of the bike it does'nt give me any problems . If i sit up , thats when the trouble starts .
Happy riding !

Neal

thanks for your replys, my rear wheel bearing were no good so i put the mc21 wheel on it, so hopefully that fixes it
cheers shane