FZ6 Light Steering

[jb1390]

What size tires do you have installed?

I am thinking maybe it is possible that they were changed from the stock size to something different, on either the front or the back.

Am I correct in assuming that the problem was there before the new tires, and continued in similar fashion with the tire replacement 500 miles ago?

And are the symptoms identical for both left and right hand turns at a similar speed?

 

[FinalImpact]

A couple things that stand out more than others here:

Either the back is lower than it should be or the nose is higher than it should be. Both result in a rake change that makes the steering light. Is there a chance the rear spring is broken or sticking? If the front forks have allot of stiction and are binding at the top (not compressing freely) this would make it very uncomfortable to ride. If you center stand the bike and then push down on seat to raise the front, do the forks top out? Do they compress a little under the bikes own weight and compress more when you sit on it? This is the principal of sag.

If you wish to solve this i urge you to take the time and measure the sag. Its a tool at your disposal and will help us see a bigger picture. IIRC mine was around 42 or 44 mm stock in the front and 28 to 32 in the back??

SAG:
1) top out the forks. Measure from lower triple to ground (front tire touching ground).
2) Sit on the bike in your normal riding position with gear on (place your palm on the wall to maintain balance while helper measures). Measure from lower triple to ground.

Repeat above 2 to 3 times and average out the measurements. Subtract 1 from 2. This is the sag. Do the same for the rear but use the grip rail as a measurement point. Repeating is to check stiction and get an average. The whole process take 10 min or less with a helper and I find that contrasting masking tape is easy to measure from. Let us know what you find.

 

[deeptekkie]

Has it been wrecked?

 

[philz]

Nope, never been wrecked or anything. I'm gonna try the stuff that FinalImpact suggested, thanks for the detailed post

 

[RJ2112]

Nope, never been wrecked or anything. I'm gonna try the stuff that FinalImpact suggested, thanks for the detailed post

Since you noticed this after the fork legs came off the bike to change the oil, I would suspect the fork legs are not clamped into the upper triple tree correctly. The difference you feel with as little as 10mm of the fork leg sticking through the top triple tree is very much like what you describe.

Look at your fork legs. The cap should just barely be above the top surface of the triple. The line between the bottom of the cap and the top of the leg should be in line with the upper surface of the upper clamp.

 

[philz]

Thanks for the suggestion RJ2112 but the fork tops are exactly in line with the upper clamp (this has been happening since before the fork oil was changed)

 

[philz]

Bar ends removed, still the same.

Did a bit of a test last night. Rode down my street and started to turn the bars just a small amount then let go, they continue to turn sharply in the same direction.

 

[Erci]

Bar ends removed, still the same.

Did a bit of a test last night. Rode down my street and started to turn the bars just a small amount then let go, they continue to turn sharply in the same direction.

You mentioned in original post that you're experiencing this at 20mph.. what about higher speeds.. does it do this at 40? The faster the bike goes, the more it should want to correct itself.

At slow speeds, it's normal for the steering to be very light since there's very little caster effect (look up rake and trail if you're interested in the physics of it). I still think the best thing you can do is to ride someone else's FZ6 to compare it to yours.

 

[philz]

I probably should've explained a bit clearer. Whilst the steering is light, it's actually the way that it continues to turn with even the smallest input which is my concern. Even just turning a small amount results in the bars wanting to go fully to lock.
I haven't rode another FZ6 so I don't know if it's just something that they all do but in the last 2 years I've had a CBR125R, SV650s, GS500e, ER5 and I currently also own a 2010 ZX6R yet none of them behave like the FZ (nor have any other bikes I've ridden)

I've replaced everything I can think of which would cause this so perhaps it's just how the FZ is?

 

[RJ2112]

I probably should've explained a bit clearer. Whilst the steering is light, it's actually the way that it continues to turn with even the smallest input which is my concern. Even just turning a small amount results in the bars wanting to go fully to lock.
I haven't rode another FZ6 so I don't know if it's just something that they all do but in the last 2 years I've had a CBR125R, SV650s, GS500e, ER5 and I currently also own a 2010 ZX6R yet none of them behave like the FZ (nor have any other bikes I've ridden)

I've replaced everything I can think of which would cause this so perhaps it's just how the FZ is?

The only other thing I can think of is that your rear suspension is not working correctly. If the chassis does not hold the intended 'level' with the road, odd things happen to rake and trail. Your situation is surely related to less than intended trail -- that has to mean the fork is more vertical than it is supposed to be.

With other fork designs, trail can be reduced by moving the axle 'forward' with respect to the midline of the fork. The ZX6 does not allow this.