S2R head shake

23-09-2020, 08:10 AM

A couple of times now I've had the front end get quite lively under hard acceleration. Not full on tank slapper but enough to make you worry! And it's when you hit the tiniest of bumps (the second time it was over a cat's eye!)

I'm guessing this is down to the front forks? I've yet to change the rear shock as some other expense always pops up

Darren69 · 23-09-2020, 08:17 AM

It could be that you've not got the rear ride height jacked up enough. Other than that then yea probably suspension related. If your rear shocks on its way out? The forks are crap on those anyway even the S4 ones aren't much better tbh.

slob · 23-09-2020, 08:57 AM

As Darren says, I’d look at the rear shock, since you say this is happening under hard acceleration.

Mr Gazza · 23-09-2020, 09:41 AM

It's almost always down to a flat on the rear tyre and corresponding pyramidal wear on the front.

23-09-2020, 09:54 AM

Tyres are brand new so definitely not them. I'll have to sort the shock next then

Nasher · 23-09-2020, 10:22 AM

Just because they are new it doesn't mean they are at the correct pressure.

My M900, was doing something similar before I discovered a slow puncture in the rear.

Nasher

23-09-2020, 10:57 AM

I will double check but the pressures are correct. It's happened once with the old tyres and once with the new, generally the bike seems easily unsettled over anything but a smooth road.

slob · 23-09-2020, 11:09 AM

do you have compression damping on the shock or just rebound?
have you ever checked sag?

Nasher · 23-09-2020, 11:12 AM

How are the headstock bearings?

23-09-2020, 01:34 PM

I've never touched the suspension, headstock bearings I've not specifically tested (I've no way of get the front off the ground)

Darren69 · 23-09-2020, 01:53 PM

You can test the head bearings if you put the front wheel over some newpapers or a couple of old magazines is probably better and you might be able to feel if it is notchy when you turn the bars. If its really worn you will hear a clunk if you push the bike forward hard with the brake on, you might even be able to feel if there is any movement.

Darren69 · 23-09-2020, 01:56 PM

Oh, take the papers/magazines out before you do the front brake test otherwise it will just slide!

23-09-2020, 03:09 PM

Cheers Darren I'll give that a go

Darren69 · 23-09-2020, 03:38 PM

I doubt if it is that, as they should have tested that at the MOT, which I assume was recently? And although that method is no real substitute for getting the wheel up and having a feel but it might show up the problem if it's really bad. ABBA stands are fairly inexpensive and probably a good idea if you don't have a centre stand and although the front lift kit is crude it does work for most things like removing wheels/forks etc.

23-09-2020, 04:23 PM

Yeah the MOT was recent and last year it was serviced by Proteam (it's done less than 1k miles since then).

I have an ABBA stand but not the front lift

23-09-2020, 08:10 AM	#1
rac3r Guest Posts: n/a	S2R head shake A couple of times now I've had the front end get quite lively under hard acceleration. Not full on tank slapper but enough to make you worry! And it's when you hit the tiniest of bumps (the second time it was over a cat's eye!) I'm guessing this is down to the front forks? I've yet to change the rear shock as some other expense always pops up

23-09-2020, 08:17 AM	#2
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,022	It could be that you've not got the rear ride height jacked up enough. Other than that then yea probably suspension related. If your rear shocks on its way out? The forks are crap on those anyway even the S4 ones aren't much better tbh. __________________ Roast Beef Monster! Termignoni and Bucci - Italian for pipe and slippers! S4 Fogarty, S4R 07T, 748, Series 1 Mirage

23-09-2020, 09:41 AM	#4
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,806	It's almost always down to a flat on the rear tyre and corresponding pyramidal wear on the front. __________________

23-09-2020, 10:22 AM	#6
Nasher Registered User Join Date: Jul 2014 Location: Portsmouth Bike: M900 Posts: 1,510	Just because they are new it doesn't mean they are at the correct pressure. My M900, was doing something similar before I discovered a slow puncture in the rear. Nasher __________________ Heaven doesn't want me, and Hell is afraid I'll take over.

23-09-2020, 11:12 AM	#9
Nasher Registered User Join Date: Jul 2014 Location: Portsmouth Bike: M900 Posts: 1,510	How are the headstock bearings? __________________ Heaven doesn't want me, and Hell is afraid I'll take over.

23-09-2020, 08:57 AM	#3
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,710	As Darren says, I’d look at the rear shock, since you say this is happening under hard acceleration.

23-09-2020, 09:54 AM	#5
rac3r Guest Posts: n/a	Tyres are brand new so definitely not them. I'll have to sort the shock next then

23-09-2020, 10:57 AM	#7
rac3r Guest Posts: n/a	I will double check but the pressures are correct. It's happened once with the old tyres and once with the new, generally the bike seems easily unsettled over anything but a smooth road.

23-09-2020, 11:09 AM	#8
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,710	do you have compression damping on the shock or just rebound? have you ever checked sag?

23-09-2020, 01:34 PM	#10
rac3r Guest Posts: n/a	I've never touched the suspension, headstock bearings I've not specifically tested (I've no way of get the front off the ground)

23-09-2020, 01:53 PM	#11
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,022	You can test the head bearings if you put the front wheel over some newpapers or a couple of old magazines is probably better and you might be able to feel if it is notchy when you turn the bars. If its really worn you will hear a clunk if you push the bike forward hard with the brake on, you might even be able to feel if there is any movement. __________________ Roast Beef Monster! Termignoni and Bucci - Italian for pipe and slippers! S4 Fogarty, S4R 07T, 748, Series 1 Mirage

23-09-2020, 01:56 PM	#12
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,022	Oh, take the papers/magazines out before you do the front brake test otherwise it will just slide! __________________ Roast Beef Monster! Termignoni and Bucci - Italian for pipe and slippers! S4 Fogarty, S4R 07T, 748, Series 1 Mirage

23-09-2020, 03:09 PM	#13
rac3r Guest Posts: n/a	Cheers Darren I'll give that a go

23-09-2020, 03:38 PM	#14
Darren69 Transmaniacon MOC Join Date: Sep 2013 Location: Sutton In Ashfield Bike: Multiple Monsters Posts: 6,022	I doubt if it is that, as they should have tested that at the MOT, which I assume was recently? And although that method is no real substitute for getting the wheel up and having a feel but it might show up the problem if it's really bad. ABBA stands are fairly inexpensive and probably a good idea if you don't have a centre stand and although the front lift kit is crude it does work for most things like removing wheels/forks etc. __________________ Roast Beef Monster! Termignoni and Bucci - Italian for pipe and slippers! S4 Fogarty, S4R 07T, 748, Series 1 Mirage

23-09-2020, 04:23 PM	#15
rac3r Guest Posts: n/a	Yeah the MOT was recent and last year it was serviced by Proteam (it's done less than 1k miles since then). I have an ABBA stand but not the front lift