Handling issues

[CookMySock]

Gurus,

My GT650R has always been rather jittery during fast cornering, so I'm trying to get to the bottom of it.

I had a more experienced rider test it, and he confirms it is definitely getting very weird past a certain cornering angle. When pushed, the nose seems dart wide out of the corner - increasing the angle of lean very suddenly and dramatically, usually resulting in what seems like an involuntary dart-right-back-in again. It takes a very firm grip on the bars to try and slow or arrest this, and even that is not very successful.

I checked the tyre specifications and they are *exactly* what the manufacturer recommends, in every respect - every single number matches. They are Bridgestone Battleaxe BT56R 160/60/ZR17 69W, and 120/60/ZR16 55W.

I tried the recommended pressures, and dropping the tyre pressures a few PSI front and rear, but that didn't seem to do much.

I set my suspension on a range of settings, and the change wasn't particularly noticeable.

So these tyres are teaching me to have balls of steel as they are scary as fuck to push hard, but I am thinking it is unwise to push them any further. 1cm of strip on the rear, and 1.5cm of strip on the front.

So is it me ? or the BT56's ? or my suspension ? Any suggestions ?

I will probably be at Taupo tomorrow (friday april 4) also.

many thanks,
Steve

[Hitcher]

Any suggestions?

Buy Ohlins.

[Blackbird]

- is your pressure gauge accurate?
- do you know beyond any uncertainty that your wheels are properly aligned?
- are your steering head bearings in good order?
- wot Hitcher said

[jim.cox]

- is your pressure gauge accurate?
- do you know beyond any uncertainty that your wheels are properly aligned?
- are your steering head bearings in good order?
- wot Hitcher said

And maybe check swingarm bushes and wheel bearings?

[BadCompany]

Don't buy a Hyosung?



Sorry had to be said.

[Hitcher]

Don't buy a Hyosung?

I suspect like any bike, a Hyosung's performance can be exponentially enhanced by the addition of decent after-market suspenders.

Most people who knock them have never ridden them.

[BadCompany]

I suspect like any bike, a Hyosung's performance can be exponentially enhanced by the addition of decent after-market suspenders.

Most people who knock them have never ridden them.

Or have never been allowed to ride them.

[Hitcher]

Or have never been allowed to ride them.

Would you like me to have a word with your mother?

[BadCompany]

Would you like me to have a word with your mother?

Its not my mother thats the issue :P

[Hitcher]

Its not my mother thats the issue

Ooh! You've got be all curious now, you enigmatic thing you.

[BadCompany]

Ooh! You've got be all curious now, you enigmatic thing you.

Woah, easy tiger!

[MSTRS:Me]

Stolen from another forum...
Good Points: Generally good grip in wet or dry. Copes well with stonking power of my Hayabusa. Turn in feels great. Tread pattern looks good.

Bad Points: Wear fairly fast (but every tyre does on a Hayabusa!). Expensive. Relatively old technology.

General comments: These are the tyres that came fitted to my Suzuki Hayabusa. I've been using them for 4 months now on a daily commute of 40 miles each way, and of course at weekends for longer trips. They are fairly good in all conditions and don't let the rear spin out unless you're doing so intentionally. Turn in is good, the bike seems to want to lean, particularly at low speeds, and braking is spot on. However, the do cool down quickly and so at sustained low speeds in traffic or in bad weather the bike feels jittery - it's only at high speeds that the grip levels start to feel planted again. After only 2000 or so miles, the front is stepped and the rear is square so they'll have to go in spite of still having decent tread depth. These are the recommended fit for the Hayabusa and other hypersport bikes, but this recommendation is nearly 10 years old and tyres technology has moved on. I will be choosing something that warms up quicker and wears better, probably from the same manufacturer, so watch this space for a review of more tyres!

[CookMySock]

ok thanks guys. I haven't even thought to check the bike mechanically, as it only has 6,000kms on the clock. It had better NOT have worn and loose shit on it.

I have tried a number of pressure gauges and they all agree.

Wheel alignment - is there a quick 'n easy check for this ? Mark-one eyeball ? Eyeometer check - how ?

Ohlins et al - where do I start looking for upgrades to this factory suspension ? I would be interested in costing this out, but I don't want to gold-plate a bike that I will soon replace with an R1 or similar. Second hard parts would be considered also. How do I tell what shocks will fit it or not ?


many thanks,
Steve

[CookMySock]

[...] at sustained low speeds in traffic or in bad weather the bike feels jittery - it's only at high speeds that the grip levels start to feel planted again. After only 2000 or so miles, the front is stepped and the rear is square so they'll have to go in spite of still having decent tread depth.

Score! Thank you mate, that pretty much sums it up. In tighter (especially rough) corners it gets weird, yet open-road sweepers are perfectly predictable. It seems that with my limited ability, I am not able to keep these tyres hot enough to perform.

Are these tyres considered pushable in this state, or should back off them for fear of provoking a disaster ? They don't seem to bite and leap - just weird and jittery.


DB

[Robert Taylor]

Gurus,

My GT650R has always been rather jittery during fast cornering, so I'm trying to get to the bottom of it.

I had a more experienced rider test it, and he confirms it is definitely getting very weird past a certain cornering angle. When pushed, the nose seems dart wide out of the corner - increasing the angle of lean very suddenly and dramatically, usually resulting in what seems like an involuntary dart-right-back-in again. It takes a very firm grip on the bars to try and slow or arrest this, and even that is not very successful.

I checked the tyre specifications and they are *exactly* what the manufacturer recommends, in every respect - every single number matches. They are Bridgestone Battleaxe BT56R 160/60/ZR17 69W, and 120/60/ZR16 55W.

I tried the recommended pressures, and dropping the tyre pressures a few PSI front and rear, but that didn't seem to do much.

I set my suspension on a range of settings, and the change wasn't particularly noticeable.

So these tyres are teaching me to have balls of steel as they are scary as fuck to push hard, but I am thinking it is unwise to push them any further. 1cm of strip on the rear, and 1.5cm of strip on the front.

So is it me ? or the BT56's ? or my suspension ? Any suggestions ?

I will probably be at Taupo tomorrow (friday april 4) also.

many thanks,
Steve

Weak low speed compression damping in the front forks, poor rebound control and a rear shock with a huge rear spring rate allied to almost no bump damping. Sorry, the reality is they are built very cheap.