Suspension Set-Up Advice

[Marb]

Right, I've got an FZR400R (3EN2) with a 660 engine in it.

Its got the non adjustable YZF750 USD's up front mounted flush with the top yoke and an FZR400RR rear swinger with wheel with stock rear shock.

I'm saving up for a proper rear shock as this one is on its way out but I've got a couple of handeling issues. Have been messing around with set up but only seem to make it worse.

In slow (40-70kmph) corners it has a difficult tip in, once tipped in it is rock steady and will hold it's line perfectly. Medium corners it tends to want to run a little wide. Fast corners it gets scary. You need to keep the bike pulling, or it'll drift wide. Fast corners (100 - fast) when i turn in on the brakes she wants to stand up, and when i let go of the brakes the front wants to wash out. Not a good feeling.

So, too sum up, if i keep it smooth and no hard braking it is all doable. Once you start to trash it a little and add some braking it all goes pear shaped. The rear is raised by 5cm, it its wearing new Dunlop sportsmarts 120 and 150.

Any tips on where too begin?

[lorenzo]

I'd start with the sag. there's some very good advice on here.

[blur1]

maybe try push the front forks through the triples by about 4-5mm then go for a ride and try it.

this is all assuming your sag/comp'/reb' are all close.

unfortunately with suspension it's a case of making ONE adjustement at a time, then going out and riding it. assess. then try another adjustment, ride, assess.....etc etc.

[BudgetBoy]

Geometry on the bike is wrong then.. Your rear has been raised 5cm which is allot. So now the bike is front heavy, meaning all the weight is on the front when you are going into corners and braking.You wouldn't drop your forks that much would you?

Also you have a larger engine in it which adds more weight to the bike affecting the overall handling.

Changing a tyre from a 150/55/17 to a 150/50/17 would affect the handling/geometry as you have lost 5mm in height,plus add to this that all tyres are NOT the same in diameter, all will vary. But thats if you get really finicky.

Basically the more force you put into the front will make it handle worse and show the problems you are having.. You need to keep adjusting the front or lower rear until you eliminate these problems.Just seems to me like you have gone beyond the "Normal" limits of the bikes handling and need to get it back to that.. And if it were me id start by lowering the rear.

EDIT:- Forgot to add.. Take notes of what you alter and write down the effect each adjustment makes. That way you can always go back to it.

[lorenzo]

To try and suss out what sort of weight bias you've got, nip up to the bathroom, get the scales and bring them down to your garage. Find a peice of wood the same thickness as your scales and stick the scales under one wheel, the wood under the other, so your bike's level. Do this for both wheels and you can suss out what sort of ratio you've got front to rear.

[Rick448]

Have you eased the rear by 5mm or 5 cm?

I'd suggest returning that to standard and trying it at that first. If it is running wide it sounds like not enough rebound damping on the front. I'd look at getting the fork revalved but speak to a suspension guy about this. I'd recommend Gareth at Reactive suspension.

[toosmooth]

All I'm hearing here is this: Unadjustable, underdamped, not even good when new, now partly knackered stock suspension.

If you're left trying to resolve this with just geometry changes (which is all you have available), I think you'll be there a long time.

Save your pennies and get some decent kit on it, I wouldn't waste too much time trying to get it perfect with this kit on.