Tank slapper
 

Was out yesterday and managed to get the tenere into a tank slapper, it was a bumpy but not to sharp a bend, there was a slight cross wind but not something I would normally worry about! It was easily controlled but could have got worse if pushed. Wondered if anyone has any set up tips to stop this? My bike has been lowered and I have checked the tyre pressures etc. cheers

What tyres are u using as a matter of interest ?

It would be useful to know whether you were accelerating, at a constant speed, or on a closed throttle?

Most likely cause is the back of the bike sitting too low, or conversely the front to high. This might be down to incorrect or imbalanced sag front/rear, being lowered with longer links but not having the front end altered to match, or a saggy shock and/or poor damping.

Mine had a tendency to do the sort of thing you describe when the OE Sachs shock began to fail (from 10k miles onward).

In answer to your questions, tyres are oe siracs only done 2000 miles , at the time I was accelerating but not to hard . Pleiades , i'm going to put the original dog bones back on and raise the forks to try(not sure I' ll be able to get my leg over , old bones not so supple any more) don't think the shock is to soft as have no wallowing problems , may play with the rebound damping and fork adjustment ? Any ideas gratefully recieved . :confused2:

Tank slapper
 

In that case I'd say the rear end riding too low, or you're running too much sag at the back.

Try adding preload first, as that's the easiest thing to alter in small steps. Then change the linkage bones back and try again. The most important thing is to do is one thing at a time. Also, test out the changes in the same corner and at the same speed if at all possible. Limit your variables as far as you can.

It's also worth checking your forks aren't topping out under acceleration as well (due to the back end riding low). If they top out during a corner and the front drops into a dip it will/could initiate a waggle.

I'm assuming you managed to arrest the tank slapper by letting off the gas, shifting the weight forward onto the front? If that's the case, then that's further evidence to support the low rear/high front scenario...

Thanks for reply, will try suggestions, if using the oe dog bones how much should forks protrude through yokes? Cheers

They shouldn't. With standard setup, they are set level with the top of the yoke.

thanks for that , will let you know how I get on ? Cheers

Finally got out today after playing with my suspension , have refitted the oe dog bones and set preload to 5 , set forks back to standard and went for ride over the same route, glad to say had no unwanted front end dramas (cheers Pleiades ) . Funny thing is now I've raised the bike , I can get on easier ( leaning over further on side stand?) and still get my feet down . Cheers

:smilies0349: Glad you got it sorted mate.

Funny thing indeed, but not unusual.

It really doesn't take much of a change in geometry (as you've found) to mess up the handling of a bike... or improve it for that matter! ;)