Tankslapping Problem

[squirrel_hunter]

Got a bit of a problem with the steering on my SV650 (99 model, Ohlins front and rear), it feels vague I have little feeling from it and it seams to be down on grip. Worse I keep getting tank slappers.

Its only shown up the last few days with the tank slapping but thinking about it the steering has felt of for a while and really showed its self up on the track at the weekend.

I've checked the tyre pressures which are good, suspension set up has not been altered any time recently. The front tyre is getting on a bit but still has a good few thousand miles left though the rear could do with changing.

I have also had the bike on the Abba Stand with the front wheel off the ground, the wheel spins freely and I can't feel any play in it and the forks move smoothly from side to side and I can feel no notchyness or play in the head bearings by playing with the forks. That said I've never felt head bearings that need replacing so can't be 100% on that.

So as for ideas, I'm thinking possibly the wheel is out of balance or the fork oil needs replacing. But I'm throwing it open for suggestions...

[Teejayexc]

Have you put weight on lately ? :smt031

[andrewsmith]

what profile tyre is it?
A 120/70 makes the front more skittish over a 120/60.

A out of balance front should be causing more vibration through the bars.

[BBadger]

Replacing the oil would be a good start depending on how old it is, cheap fix and it will improve the front feel anyway.

With the front end up it couldnt hurt to check the head bearings out, bit of grease, then re-tighten so that you know its all going back together correctly.

If you get this out the way then it must be down to tyres or the wheel?

[Bibio]

doubt that you are getting 'tank slaps' more like head shake. a tanks slapper will rip the bars out your hands or cause the front of your bike to become completely uncontrollable and usually bounce the front from side to side as it goes from lock to lock.

head shake (which can be severe) on the other hand will induce a wobble felt threw the bars under heavy acceleration out of corners or over bumps.

as mentioned above you could try a heavier oil or more pre-load i would also check the swingarm bearings for excess play.

but i would wait till someone more knowledgeable come along for a better explanation :-)

[TamSV]

but i would wait till someone more knowledgeable come along for a better explanation :-)

I'll chip in while we're waiting. :)

Don't forget about the rear shock - it might be due a service?

Trying to set up the new suspension bits on the cafe racer I was getting something similar. A generally vague feeling and a bit of reluctance to turn followed by head shake when accelerating out of bends. I couldn't solve it by doing anything at the front.

However, when I set the rear sag properly (I had too much) and fiddled with rear comp (I didn't have enough) it seems to have sorted it.

Don't entirely know how or why - I'm just twiddling adjusters and seeing what happens. :) Maybe too much squat at the rear turning it into a cruiser on the corners and letting the front go light under power?

[Stig]

Head bearings, fork oil, worn front springs or rear shock. You might also want to check the swingarm pivot.

[gruntygiggles]

doubt that you are getting 'tank slaps' more like head shake. a tanks slapper will rip the bars out your hands or cause the front of your bike to become completely uncontrollable and usually bounce the front from side to side as it goes from lock to lock.

head shake (which can be severe) on the other hand will induce a wobble felt threw the bars under heavy acceleration out of corners or over bumps.

as mentioned above you could try a heavier oil or more pre-load i would also check the swingarm bearings for excess play.

but i would wait till someone more knowledgeable come along for a better explanation :-)
Great advice for many, but Steve knows a tankslapper when he feels one. I don't know why he's complaining though...I would have thought he'd be grateful for any kind of slapper at the moment! Ha ha x