fish tailing like mad

[davepreston]

for the past day or two the back end of the bike has not been feeling right (you know what i mean you know your own bike) last night while braking it keep feeling like the back was trying to overtake the front, now even looking at a bend and she starts fish tailing all over the place. i cant belive these words are comeing out of my mouth but im now scared to ride her, and as some will testify i will ride anything (yc remember my front brakes) need help soonest or reccy for dales is out and summer if it dont get better,
sorry but its actually got to me and still a bit freaked out had to ride 30mile with it like that

[dizzyblonde]

Everything nice and bolted up on the rear?
Tyre gone square? What have you tinkered with recently?

[fizzwheel]

Tyre pressues, check them.

I've had similar weird handling traits caused by lack of a few PSI in one of the tyres. A puncture in the rear tyre also resulted in some very strange handling behaviour as well.

[timwilky]

Tyre pressues, check them.

I've had similar weird handling traits caused by lack of a few PSI in one of the tyres. A puncture in the rear tyre also resulted in some very strange handling behaviour as well.

+1,

my bros mille started behaving very badly, turned out to be dodgy valve cores, only leaked at speed.

[davepreston]

no tinkering will check psi in a minute

[dizzyblonde]

+1 to Fizz, a nail in my rear, with a slow puncture made very odd behaviour on roundabouts. Not nice :-(

[cuffy]

Rear wheel alignment?
Is it happening when on a constant throttle, under braking or giving it some berries?

[Rocket]

It's been raining?

[davepreston]

It's been raining?
thanks mate but i ride 365
wheel alignment is bob on and it is cornering and braking ,darent give it the berries the way its handling

[Rocket]

How hard do you have to brake before the problem shows up?

[Frank]

Mine went like that and we couldnt get exactly to the cause of the prob,in time for my hols
I ended up trading it in.
good luck with it matey

[Jamiebridges123]

If you're chattering up the back it will try to step out.. maybe it's new tyre time.. :|

[davepreston]

i starts even with slight braking
whats chattering up?

[davepreston]

good place to get tyres near preston? avon storms or something else ,loads of motorway but 20 odd rideouts a year too

[timwilky]

get down to farnworth (http://www.yell.com/listings/DoFindListings/4559425/B-and-C-Performance-Tyres/Tyres). well recommended

[Biker Biggles]

Happened suddenly?Either somethings broke or tyre pressures.If the tyres are OK then you need to get it up on a stand and check the headstock bearings,the swingarm bearings and the wheel bearings.Also check everything for tightness-----wheel spindles chain adjusters,and have a look at the rear shock linkages.

[fizzwheel]

I dont want to risk the repeating myself, but have you checked the pressures ?

[TazDaz]

Are you changing down whilst braking and possibly spinning the rear up slightly?

[Jamiebridges123]

Are you changing down whilst braking and possibly locking the rear up slightly?

Fixed for ya' mate. :D

[TazDaz]

Fixed for ya' mate. :D

That's not what I meant though...

If you knock it down a few gears whilst on the front brake, if the revs happen to bounce high enough it may spin the wheel up a bit which can feel weird.

[Bluefish]

Good job you haven't sold the Virago yet :grin:

[Alpinestarhero]

Following on from tazdaz's reply, do you "blip" the throttle on downchanges to reduce the risk of the rear tyre loosing grip?

Inspect for any oil leaks, chain lube fling onto the rear ture etc. You say the problem also happens during cornering - is it more prominent through either left turns or right turns?

I'm going with tyre pressures at this stage, but there could be a slim chance its the rear shock. How old is the bike, and its milage?

[davepreston]

waiting for mate with tpg
it might just be me but right turns are really scary
15000 on the bike its a 99

[ophic]

taken into account the weather? not being funny here - we've some good dry spells followed by a load of rain - this will make the roads very greasy.

[Alpinestarhero]

waiting for mate with tpg
it might just be me but right turns are really scary
15000 on the bike its a 99

Check the right side of both tyres. Check the rear brake is not binding aswell? With those miles and that age, the rear shock will be a bit tired but shouldn't be giving those problems, I'd think you can rule it out

[fizzwheel]

If you knock it down a few gears whilst on the front brake, if the revs happen to bounce high enough it may spin the wheel up a bit which can feel weird.

Whats driving the wheel in that scenario ?

How do you spin the wheel in the direction of travel ( which is what I think you are impying ) when the throttle is shut and no fuel is being admited to cylinders to burn to move the bike forward.

Cant see what you're getting at...

[Alpinestarhero]

Whats driving the wheel in that scenario ?

How do you spin the wheel in the direction of travel ( which is what I think you are impying ) when the throttle is shut and no fuel is being admited to cylinders to burn to move the bike forward.

Cant see what you're getting at...

Perhaps he means that the decelaration of the rear wheel is too great...low gear + high rpm = lots of engine braking, eeeeek

[TazDaz]

Whats driving the wheel in that scenario ?

How do you spin the wheel in the direction of travel ( which is what I think you are impying ) when the throttle is shut and no fuel is being admited to cylinders to burn to move the bike forward.

Cant see what you're getting at...

Perhaps he means that the decelaration of the rear wheel is too great...low gear + high rpm = lots of engine braking, eeeeek

Obvisouly this could be nonsense, I'm not an expert or owt - just I thought this was one of the reasons racers use the rear brake quite heavily!

If you're hooning down the road, apply the front brake so the weight is on the front, but at the same time knock it down a few gears which will cause the revs to shoot up. Won't this cause the rear to try and spin quicker than the front??? :smt102

[DarrenSV650S]

If it is just happening on right handers I'd check the wheels are aligned as has been already said.

[sam anon]

Obvisouly this could be nonsense, I'm not an expert or owt - just I thought this was one of the reasons racers use the rear brake quite heavily!

If you're hooning down the road, apply the front brake so the weight is on the front, but at the same time knock it down a few gears which will cause the revs to shoot up. Won't this cause the rear to try and spin quicker than the front??? :smt102

No, the revs only rise on downchanges as the engine is then being driven by the rear wheel. The engine will only rev as much rear wheel makes it rev, so won't spin up the back.

The engine braking can overcome the rear wheel and lock it up though, as editted.

As has been stated, I'd look at head bearings, tyre pressures, and all the swingarm pivots.

[fizzwheel]

Won't this cause the rear to try and spin quicker than the front??? :smt102

No, Whats turning the wheel if the throttle is shut ?

The only thing that makes back wheel turn faster than the front is the application of the throttle. Which if you are braking is shut.

Whats happening is that the engine revs are trying to match the speed of the back wheel when you let the clutch out.

I.e if your diong 50mph in 6th and then knock it down to 3rd, then the engine revs will rise till the engine is turning the rear wheel at an appropriate speed that gives 50mph in 3rd gear for example 9000 rpm, which is why the revs rise.

Basically you lock the back wheel and thats why alot of people blip the throttle on down changes so that the engine is revving at the appropriate RPM for the gear that you want at the speed you want, so you dont lock the back wheel.

Apologies if I havent explained this very well and we've derailed the OP threa now...

[flymo]

just I thought this was one of the reasons racers use the rear brake quite heavily!

Actually they dont :cool:

[Alpinestarhero]

Obvisouly this could be nonsense, I'm not an expert or owt - just I thought this was one of the reasons racers use the rear brake quite heavily!

If you're hooning down the road, apply the front brake so the weight is on the front, but at the same time knock it down a few gears which will cause the revs to shoot up. Won't this cause the rear to try and spin quicker than the front??? :smt102

no - lower gears are for lower speeds; at 40 mph in 4th, you are running 4000 rpm on an SV-s with standard gearing. Clonk down to third and this goes up to around 4900 - 5000 rpm with increased engine braking...its this increase engine braking that is trying to decelerate the rear wheel....essentially, the rear wheel is trying to drag the bike via the engine braking. The lower the gear and hence the higher the revs, the more engine braking and more snakey snakey fun you get. Or not fun, in this case. Racers use the rear brake heavily for a couple of reasons. One is to stop quicker :D the other is to settle the bike before going into a turn

the lower gear and the higher RPM's still means the rear wheel is going the same speed

[davepreston]

welcomed derail as i have learned something new too , never a bad thing :)

[TazDaz]

I've clearly learnt something too! :)

You can probably all tell that I've only been interested in bikes for the past 10months, maybe it was locking up under braking/engine braking that I've confused myself with then! :)

Apologies for the derail...

[Biker Biggles]

Checked those tyre pressures yet?

[davepreston]

still waiting for numpty brains to tip up "i'll be there in ten my ar5e

[DarrenSV650S]

I think you should invest in a tyre pressure gauge

[Rocket]

+1 Darren. Never underestimate the importance of tyre pressures

[Richie]

I'll put money on it is the tyre pressures...
happend to me and found out that I had a puncture in the rear tyre.

[yorkie_chris]

The engine braking can overcome the rear wheel and lock it up though, as editted.

No it cannot. Not in a million years will engine braking LOCK a wheel.
A slide, yes. A lock, no. The difference is pretty marked. Go try it...



Dave is it actually breaking loose? What tyres? How many miles? What pressures?

If it just feels like it's wagging it could be anything on the chassis, swingarm bearings, a collapsing wheel bearing, a faulty tyre etc. Check carefully for any bulges on the sidewall or other obvious fault. It could even be a f##ked shock making it feel like it's moving around (or even a standard shock "working" normally!!)

[yorkie_chris]

no - lower gears are for lower speeds; at 40 mph in 4th, you are running 4000 rpm on an SV-s with standard gearing. Clonk down to third and this goes up to around 4900 - 5000 rpm with increased engine braking...its this increase engine braking that is trying to decelerate the rear wheel....essentially, the rear wheel is trying to drag the bike via the engine braking. The lower the gear and hence the higher the revs, the more engine braking and more snakey snakey fun you get. Or not fun, in this case. Racers use the rear brake heavily for a couple of reasons. One is to stop quicker :D the other is to settle the bike before going into a turn

the lower gear and the higher RPM's still means the rear wheel is going the same speed

ASH you're a scientific lad, have a think about it.

When braking heavily with the front how much weight is there going to be on the back wheel? How is weight on an interface related to reaction force? How is reaction force related to static friction?

[Rocket]

So the collective wisdom of the .org is that something might have gone down on Dave - his rear tyre :D

[dizzyblonde]

If it just feels like it's wagging it could be anything on the chassis, swingarm bearings, a collapsing wheel bearing, a faulty tyre etc. Check carefully for any bulges on the sidewall or other obvious fault. It could even be a f##ked shock making it feel like it's moving around (or even a standard shock "working" normally!!)

Yeah matts just said that. As for the shock thing, this is why i asked if all the nuts n bolt were nice and tight....remember the odd feeling I had on mine, and there was a bit of a loose one on the bottom of my old shock:-x Its a good job it was due in to see you!

Dave really go over your rear tyre with a fine tooth comb, and check to see if any 'grit and stones' could be really a tiny pinhead of a nail. The roundabout puncture I had, I missed several times, and found a tiny metal pinhead in my tyre. When rob pulled it out it was a giant bloody rivet pin.:smt013

[Jamiebridges123]

Having a puncture itself won't affect your handling.... it's the pressures. Most "punctures" lose a couple of PSI a week..

[davepreston]

going on paddock stand for inspection during break in rain

[dizzyblonde]

Having a puncture itself won't affect your handling.... it's the pressures. Most "punctures" lose a couple of PSI a week..

having a hole in the first place don't help either:rolleyes:

[Jamiebridges123]

To be fair if the hole is enough to let a sizeable amount of air out, IE pressures are running low anyway, a good rider should notice by the end of his/her road. It'd weave and feel very slow to turn in.

Dave I'll ask again have you checked your pressures.....? You don't need it on the paddock stand do to that and it takes all of 30 seconds. :|

[ophic]

No it cannot. Not in a million years will engine braking LOCK a wheel.
It can if you stall it :p

[DarrenSV650S]

And it can if you are trying to bump start it. Bloody impossible

[Steve_God]

Dave... having seen your rear tyres I 'think' I know where the problem lies ;)
All part of the fun in getting that extra 1k miles out of the tyre :p

[yorkie_chris]

It can if you stall it :p

Ahhh but then it's static compression.

And how often do you stall it going into a corner at speeds? :rolleyes:

Knew someone was going to be pedantic about that...

[ophic]

Knew someone was going to be pedantic about that...
Glad I didn't disappoint. Agreed it was pure pedantry. You'd have to deliberately set out to stall it.

[Luckypants]

Dave, have you checked your tyre pressures yet? :rolleyes:

[timwilky]

Dave

Do I need to bring a pressure gauge to the Nacky tonight?

[sam anon]

No it cannot. Not in a million years will engine braking LOCK a wheel.
A slide, yes. A lock, no. The difference is pretty marked. Go try it...


I'd rather not! You know what I meant!

[vardypeeps]

LOL has he checked that pressure yet?
If it aint that like chris said get checking for play in bearings and look for any signs of leakage around the shock.

[yorkie_chris]

I'd rather not! You know what I meant!

Why not?

One of the first things I did when I got the bike was operated controls rather viciously to find out how much ham-fistedness it would allow me to get away with! It's an important thing to know IMO.

[dizzyblonde]

Why not?

One of the first things I did when I got the bike was operated controls rather viciously to find out how much ham-fistedness it would allow me to get away with! It's an important thing to know IMO.

why would you want to purposely put yourself at risk of killing yourself with a great big firey ball of death:rolleyes::p:D


#Do not ttry this at home folks!# and not an important thing to know IMO;)

[fizzwheel]

why would you want to purposely put yourself at risk of killing yourself with a great big firey ball of death:rolleyes::p:D

Because sometimes it can be useful to understand and feel what a bike feels like on the limit of adhesion. That way you can extract the maximum performance from it and feel what its like when its about to brake traction.

I'm frequently amazed by how hard I can brake on any bike I ride. Its much much harder than I think I can. In an emergency situation being proficent at braking and knowing how to deal with a locked wheel or just how much pressure you can put on the lever IMHO might make the difference between hitting the car thats just pulled out in front of you and avoiding it altogether.

[davepreston]

tyre fubared diz was right slow puncture it didnt help that they also looked like racing slicks so new tyre it is :(

[fizzwheel]

Ah but at least thats a simple fix. Glad you have got the bottom of it.

[ophic]

why would you want to purposely put yourself at risk of killing yourself with a great big firey ball of death:rolleyes::p:D


#Do not ttry this at home folks!# and not an important thing to know IMO;)
debatable. Attempting something under controlled conditions is not the same as coming across something whilst out riding. It's important to know how the bike will react. It's no different to practising recovering from a front wheel lock under braking.

Admittedly a similar mind-set ended up with my bike back at the dealers for repairs with 13 miles on the clock from new... but seeing how tight it will turn on a greasy road is not the same thing :D

EDIT: Fizz said it all better than me. I have to do work in between posting on here sometimes...

[dizzyblonde]

Because sometimes it can be useful to understand and feel what a bike feels like on the limit of adhesion. That way you can extract the maximum performance from it and feel what its like when its about to brake traction.

I'm frequently amazed by how hard I can brake on any bike I ride. Its much much harder than I think I can. In an emergency situation being proficent at braking and knowing how to deal with a locked wheel or just how much pressure you can put on the lever IMHO might make the difference between hitting the car thats just pulled out in front of you and avoiding it altogether.


fair enough, but I'm more in the way of finding out naturally(and subconciously learn). Personally I'd rather not go out to cause myself trouble. I do know the SV brakes harder than you would expect in emergency. Although I'm not hamfisted in the first place, so maybe(and I'm not suggesting I'm marvellous) I put myself in a better positon in the first place for not locking things up when in a hurry. Its like when your a kid and you pull on the front brake too hard and end up over the handle bars......you anly need to to it once to learn!

[Bluefish]

Tyre pressues, check them.

I've had similar weird handling traits caused by lack of a few PSI in one of the tyres. A puncture in the rear tyre also resulted in some very strange handling behaviour as well.


6 pages later dave checks. ;)

[Luckypants]

tyre fubared diz was right slow puncture it didnt help that they also looked like racing slicks so new tyre it is :(

Glad you got to the bottom of it. Tyre pressures it was then (caused by puncture) - what I don't understand is why the unhappy face at replacing a bald tyre?

[davepreston]

cant do reccy tomorrow for dales run

[branny]

Get it down to Shorrocks in lower penwortham mate. They do me good on tyres.

or even better... if you're near the docks, use Dave Helm, he is a good guy. tel:732007

[yorkie_chris]

why would you want to purposely put yourself at risk of killing yourself with a great big firey ball of death:rolleyes::p:D


#Do not ttry this at home folks!# and not an important thing to know IMO;)

So when's better to learn when a wheel is about to lock? Under controlled conditions, maybe in a car park, or a totally empty road?

Orrrr doing it "naturally" and learning when that blind spastic has pulled their cage out in front of you at rush hour?

I think we know who's more likely to end up under the car in that situation.

You don't get any better at anything unless you leave your comfort zone once in a while.

[Richie]

So did Dave check his tyre pressures...?



in that case I'll probably see DaveP on the Ar09 in 2011....

[davepreston]

So did Dave check his tyre pressures...?



in that case I'll probably see DaveP on the Ar09 in 2011....
listen here R.E.M.F boy unlike your lot i do on time where needed :p lol

[Richie]

.... ;-).....

catch you soon.

[Baph]

I know the thread has been answer, but I had to pick up on this...

If you knock it down a few gears whilst on the front brake, if the revs happen to bounce high enough it may spin the wheel up a bit which can feel weird.

It can do, yes, more in a sec...

Whats driving the wheel in that scenario ?

How do you spin the wheel in the direction of travel ( which is what I think you are impying ) when the throttle is shut and no fuel is being admited to cylinders to burn to move the bike forward.

Cant see what you're getting at...

Fizz, I'm sorry but that's a rather large assumption. At no point (that I can see) did anyone say under braking the throttle was shut.

Supermoto technique's mean you can ride a bike where you're heavy on the front brake, whilst actively opening the throttle. I won't go into detail as I would hate for someone to read this & think "That sounds like a good craic, I'll try that."

It will step the back out going into a corner, and it takes a certain element of bravery the first time it's attempted. Then you need to pull over & change your pants.

Sorry, I'll go sit in the pedantic corner now... :( :lol:

[fizzwheel]

Fizz, I'm sorry but that's a rather large assumption. At no point (that I can see) did anyone say under braking the throttle was shut.

Yep but a reasonable one I think.

I for one dont ride along with the throttle pinned open and the front brake on...

[Baph]

I for one dont ride along with the throttle pinned open and the front brake on...

[pedant mode]You don't do it with the throttle pinned open, on an SM bike, that would result in an interesting wheelie when the tyre grips mid bend. :shock: That's part of the reasoning I didn't go into detail in how to accomplish it. [/pedant mode]

I learnt the technique on a friends KTM, and regularly do so when I'm playing, even on the SV. I find it allows for a faster paced ride, though I will conceed that it is vastly more dangerous (esp on public roads).

But you go through rear tyres too quickly. :(

[Magnum]

If you're hooning down the road, apply the front brake so the weight is on the front, but at the same time knock it down a few gears which will cause the revs to shoot up. Won't this cause the rear to try and spin quicker than the front??? :smt102


If anything it would slow down the back wheel. Thats why you downshift to slow down, the gears can do some of the braking for you. When my bike jumps out of second sometimes it feels like i just slammed on the rear brake.

[Alpinestarhero]

I know the thread has been answer, but I had to pick up on this...



It can do, yes, more in a sec...



Fizz, I'm sorry but that's a rather large assumption. At no point (that I can see) did anyone say under braking the throttle was shut.

Supermoto technique's mean you can ride a bike where you're heavy on the front brake, whilst actively opening the throttle. I won't go into detail as I would hate for someone to read this & think "That sounds like a good craic, I'll try that."

It will step the back out going into a corner, and it takes a certain element of bravery the first time it's attempted. Then you need to pull over & change your pants.

Sorry, I'll go sit in the pedantic corner now... :( :lol:

Valentino Rossi has said that he uses a similar method, or has used a similar method, to help settle his motogp yamaha in turns. Ok, thats valentino, but the physics is still the same. I can see how it would work

[Paul the 6th]

glad to hear you've sorted the tyre dave - was worried I'd have to do the recce on my own....

.....:smt077

[-Ralph-]

A slide, yes. A lock, no

Sorry, I'll go sit in the pedantic corner now... :( :lol:

Take some extra sandwiches, a big flask, two packets of crisps and two Mars bars. YC will be waiting for you when you get there ;)