Weave into tank slapper at 45mph ish - .: XT660.com

wavesnwheels · # 1 26-03-15, 13:20

Hi

I was riding the other day fairly quickly through some nice country roads. As I entered a village I started to slow down, at about 45mph I took my hands off the bars and looked round, when I looked back the bars were shaking and had I not grabbed them would have entered a full on tank slapper.

I pulled over and checked what I could, everything looked ok and nothing felt loose. I tentatively sent off again and at 45 took my hands from the bars again and the same thing happened. On returning home I checked the tyre pressures which were 30 f and 33 r this is what the manual states for under 90kg. Just to be on the safe side I upped them to 33 f and 36 r and went out again. This was a few days later. The same hands off bars at 45 and no wobble. I can't believe that running the tyres 3 psi more has cured it and am concerned that after my spirited riding prior to the original instance was showing up something like a failing front wheel bearing?

I will obviously investigate this further but wondered if this rang any bells with anyone who could offer advice.

Thanks

If I've posted in the wrong place please move and apologies.

keithy2 · # 2 26-03-15, 21:14

[QUOTE=wavesnwheels;208198]Hi

I will obviously investigate this further but wondered if this rang any bells with anyone who could offer advice.

Thanks

DONT TAKE BOTH HANDS OFF THE BARS

Posiden · # 3 26-03-15, 21:32

Might not be related but i heard of a few folk complain about tank slappers on the KTM 950 SM.
It was only after a while people noted that if you sit back on the seat just a bit to far it takes just enough weight off the front to cause it to be 'a bit flighty.'

dommiek · # 4 26-03-15, 21:59

Quote:

Originally Posted by wavesnwheels

Hi

I was riding the other day fairly quickly through some nice country roads. As I entered a village I started to slow down, at about 45mph I took my hands off the bars and looked round, when I looked back the bars were shaking and had I not grabbed them would have entered a full on tank slapper.

I pulled over and checked what I could, everything looked ok and nothing felt loose. I tentatively sent off again and at 45 took my hands from the bars again and the same thing happened. On returning home I checked the tyre pressures which were 30 f and 33 r this is what the manual states for under 90kg. Just to be on the safe side I upped them to 33 f and 36 r and went out again. This was a few days later. The same hands off bars at 45 and no wobble. I can't believe that running the tyres 3 psi more has cured it and am concerned that after my spirited riding prior to the original instance was showing up something like a failing front wheel bearing?

I will obviously investigate this further but wondered if this rang any bells with anyone who could offer advice.

Thanks

If I've posted in the wrong place please move and apologies.

My old VT500 despatch bike did exactly the same, closed throttle, decelerating and hands off the bars usually talking on or listening to the radio. Some bikes just do this. I wouldn't be too concerned!

fridolin · # 5 27-03-15, 06:59

Quote:

Originally Posted by dommiek

My old VT500 despatch bike did exactly the same, closed throttle, decelerating and hands off the bars usually talking on or listening to the radio. Some bikes just do this. I wouldn't be too concerned!

I would, because my tenere doesn't do this.

sweller · # 6 27-03-15, 08:49

My Ten would shake its head loaded up at low speeds (5-10 mph) - now I know that's not what you experienced - but I found increasing the preload reduced its tendency to shake.

I also repacked and adjusted the head bearings a couple of months after and I've not had to muck about with the preload since.

dommiek · # 7 27-03-15, 10:25

Quote:

Originally Posted by fridolin

I would, because my tenere doesn't do this.

Taking BOTH hands off the handlebars whilst decelerating is not to be recommended. Any bike will be less stable like this and it won't take much to induce a weave.

Schnidely · # 8 27-03-15, 11:36

A correctly set up bike shouldn't wobble with hands free riding. Two major causes are steering head bearings on there way out and or front tyre wearing unevenly. Most tyres wear unevenly if you look closely. Loosening the head bearings a pinch if they are notchy and increasing the tyre pressure should alleviate the problem. Good luck

wavesnwheels · # 9 27-03-15, 12:44

Thanks for the replies guys.

Quote:

Originally Posted by keithy2

DONT TAKE BOTH HANDS OFF THE BARS

Well how will I be able to do seat stands then ;-)

Quote:

Originally Posted by sweller

My Ten would shake its head loaded up at low speeds (5-10 mph) - now I know that's not what you experienced - but I found increasing the preload reduced its tendency to shake.

I also repacked and adjusted the head bearings a couple of months after and I've not had to muck about with the preload since.

I rode it today without the panniers which normally carry my work gear and instead carried it in a back pack. (Mainly because one of the bolts holding the r/h side pannier mount had disappeared) but the bike definitely felt more stable with the weight further forward. I think increasing the rear preload would definitely help when loaded up.

Quote:

Originally Posted by Schnidely

A correctly set up bike shouldn't wobble with hands free riding. Two major causes are steering head bearings on there way out and or front tyre wearing unevenly. Most tyres wear unevenly if you look closely. Loosening the head bearings a pinch if they are notchy and increasing the tyre pressure should alleviate the problem. Good luck

The bikes only done 5700 miles and I think they readjust the head bearings at the first service. I will check this though. I was hoping to get another few thousand out of the front tyre but it is looking a bit uneven. My first though was tyres so I guess I should just bite the bullet and get a new set now. Great I shall now trawl through the endless "what tyre" threads, on second thoughts I might just stick with the michelins although 6k isn't very good on a bike with less than 50bhp

sweller · # 10 27-03-15, 13:02

It was the front preload I increased.

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