Steering Problem

[iCraig]

Well I noticed when I set off from a set of traffic lights yesterday, that when I pulled away (rather quickly) the front end began to, how can I put it, wiggle from side to side like it was beginning to tank slap and then settled down.

I also noticed it when I took both hands of the bars it did it then too for a short period.

I have checked the steering head bearing and it seems normal, and all the front end seems all tight and everything, so I am thinking it may be down to the tyre pressures, I changed them from what Kawasaki recommended to Bridgestones recommendations and the bike felt more stable with these but do you think it could cause this phenomina or could it be something else I haven't checked?

Thanks In Advance

Craig

[MarJay]

maybe this just happens to all bikes when they pull away briskly. Especially those that are slightly faster than a GS500E!
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[billy whizz]

There has been millions of pounds spent researching the "tank slapper" phenomena but no real evidence points to any one factor being the major cause of one. They do know that a combination of things will cause one more readily i:e tyre pressures, steering geometry, suspension and wheel base. You could spend a lot of time and money and still get one just when you don't want it, my best advice is to fit a good quality steering damper as your bike has shown that it is susceptible to them.
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[MarJay]

[iCraig]

I rated it funny, cos the GS was so sodding slow and crap and I thought that was what your hinting at .

As you say most bikes may do it just thought there maybe something wrong, but I've never ridden something this fast and handles so well (compared to a GS500 that is).

[stinkwheel]

A soft rear tyre will do that though, especially if you take a pillion without increasing the tyre pressure.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[iCraig]

The rear tyre is at 2.7 BAR, which is what Bridgestone recommend.

And my tyre pressures are checked weekly .

[jonboy]

If the front wheel lifted off the floor slightly and then touched down slightly off straight, it would explain it. All bikes have a tendency to do that.

[Kickstart]

Hi

They are listed in the workshop manual as 32psi rear, so 2.7 bar sounds quite high.

However it is a GPZ500. Check for play in the rear suspension linkage. Find it then get a bush made up (the bushes new from Kawasaki are just as bad).

Also really check the steering head bearings carefully.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[stinkwheel]

Forgot you were talking about a GPZ500s.

If there is less than 2mm of tread on your front tyre it will do this and get progressivley worse as the wear increases.

I also find that BT45s also go through a 'phase' about 3-500 miles after they are put on of 'odd' handling which passes within about 50-100 miles.

It is just a 'feature' of the bike. If you want to see how bad it can get, put continental tyres on it! (actually, don't, you will fall off)
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[iCraig]

The bike has had 2 brand new BT45's fitted about a 1000 miles ago, so theres plenty of tread on them and the tyre pressures are set at what bridgestone say.

Weirdly the bike didn't do it today when setting off from the same lights it has done it at before :\.

[iCraig]

[iCraig]

Well following on from my first few posts I have noticed that the wheel is moving about very slighty on the axle, I will tighten the bolts to see if that makes any difference if I doesn't then what else could it be? Wheel bearings??

[Kickstart]

Hi

99% likely to be the wheel bearings.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[stinkwheel]

The front wheel bearings went on my GPZ500 at about 28k miles if that is any help.

If you are going to replace them, don't get them from a bike dealer, they take the piss with their prices. Look in the yellow pages for a bearing factor, if you go in with the number stamped on the side of the bearing race (or take the old one with you), they will do them for 2.50 to a fiver each. They will have them in stock as it is a very common size.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[iCraig]

[Kickstart]

Hi

Grab the bearings. The seals should be replaced but I would not bother normally if you are getting rubber sealed bearings ("6202 2RS" I think for the front of a GPZ500S). I am free next weekend I think so if you want you can wander down and we can fit them.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[stinkwheel]

What I usually do with those bearings is to prise one of the rubber seals off each one, fit the first one with the open end towards the centre of the wheel, install the tube-spacer then pack the gap round it with grease, I then fit the other bearing over the top of it. This gives you a 'pool' of grease rather than just relying on what is inside the bearing.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[iCraig]

Well having checked the bike out this morning and a friends checked it out too there doesn't seem to be any play what so ever in the front wheel, and my mate said he didn't reckon the wheel was moving at all on the axle, so it must just be my defective eyes.

Yet the bike is still showing signs of the "wiggling", I've now also noticed it doing it about 30-50MPH If I take my hands off the bars or just have them lightly in my grip. So I am still non the wiser of whats up with the bike .

Oh and Keith thanks for the offer of helping me do them, I may have take you up on it .

[Hex]

Wheel out of ballance or head bearings?

Or just your looking for something to be wrong as you think it feels different.
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[PsychoHippy]

I had this on the ZZR when I didn't align the rear wheel correctly after adjusting the chain. Just because it's affecting the front end, you can't rule the back end out.
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[iCraig]

Would sort of explain why it only started shortly I had my rear tyre replaced.

Oh and Hex, I would expect a bike to be steady when I take my hands off the bars on a smooth road like the rest of my bikes have been so yes its all in the feel.

[iCraig]

Well thanks for all the help guys but I am still non the wiser of what is up with the front end as its still feeling a tad weird so to put my mind at rest I have decided to book the bike in with a session with the local mechanic who hopefully will diagnose any problems he finds .

[iCraig]

Cheers guy for all the help, it was the tyre pressures after all as the mechanic said.

I rang Kawasaki today and they confirmed they recommend 32PSI in the BT45's and not the 36PSI Bridgestone recommend!

So to Bridgestone and to Kawasaki .