Bike wobbly at speed and falls into turns. Normal?

This weekend I was able to take my project 82 GPZ750 back on the freeway, something the bike hadn't done since before the P.O. bought it years ago. I noticed two issues that are probably caused by the cupped rear tire, or could point to another problem.

1. The bike felt wobbly at freeway speeds. It just didn't feel like it wanted to track straight. the bike felt like the wobble was coming from the front end, though I didn't move the bars, and it is very tough to tell where the wobble was coming from.

2. Going slowly around turns I noticed that the bike would kind of fall into the turn. On previous bikes I've owned, one could almost let go of the handle bars and lean to turn. On my GPZ it feels like the front wheel wants to keep turning, and I have to use handlebar input to hold the line I want. If relevant, my reference bikes are an FZ6 and GS500.

Are these normal issues with this bike, or just common characteristics of tires possessing bald and hence flattened mid-sections?

Other facts that might be helpful: The front tire looks fairly new. The rear tire was aligned using the marks on the sides of the swingarm after adjusting the chain. The front forks are straight, and work normally when compressed. I couldn't make the front tire move by holding the handlebar still and pushing the front tire back and forth. The rear shocks felt comfortable, meaning I think they did their job of smoothing bumps.

First thing is first put the bike on the center stand ( or jack) try to find a way to suport it and make shure its stable. Now check the front wheel by shaking the handle bars or have a friend hold the bars while you try to wiggle the front tire there should be no play.

Next break out some tools check every nut and bolt on the front forks wheel nuts and all dont strip them just checkin to see if everything is tight. Now would be a good time to have a manul, somthin alot of these guys download for free. I am looking for a good kawasaki service manul, I hear they are the best.

After checking the lower stough try to lift the front tire not the suspension the wheel if there is play All Balls makes taperd stem berrings.

Then to the rear you said the tire was shot Avon makes a road rider and thats what I run on the back verry good road tire.

Jack up the rear check for play side to side in the rear wheel by shaking it side to side if good shake harder lol and if there is play in the swing arm berrings you should be able to see it.

All parts can be found at Z1 enterprises

If in dout switch it out!! My friends say I just thro parts at my bike but Its almost 30 and has had a hard life. If you value your life berrings are a good investment and tires a must!

I dont know much just tryn to help someone with a big brain will chime in soon Im goin back to smokin lol :silly:

Not normal at all!

Sounds like a case of low air pressure in the tires.

steell wrote: Sounds like a case of low air pressure in the tires.

When my bike has that "falling into turns" feeling, it's tire pressure... usually telling me I picked up another damn nail. I swear i could re-roof my house with the nails I've picked up over the years.

Suspension...

Forks straight?
Proper amount of fork oil!? and seals not leaking -Front and Rear.
Hell if the rear shocks are origional - CHUCK THEM.
Probly good time to throw in some new springs in the front too...

Tire pressures good?

The service manual is deffinately a good one to have.
It may take a while to find/refine your problem, but in the end with the work put in, you'll have one smooth riding machine that is comfortable and predictable.

Good luck.

I've got the service manual. The front and rear wheels don't move when I try to move them back and forth. For now I'm going to attribute it to the bald rear tire, and I'll re-evaluate things once I have fresh rubber on her.

Would I really need to replace the stock rear shocks? The GPz spent half of her life as a garage queen, and then half of it sitting unused outside. Just under 20,000 miles on her. She rides surprisingly smoothly. Better than my GS500 ever did, even after changing springs and oil a couple of times, but not as nicely as the FZ6.

Put new, quality tires on it and the problem will improve. Bad tires WILL cause wobble and the falling in corners effect (not to mention they can kill you!). I would also replace the shocks with new, quality units. My stock KZ650-C1 shocks (granted, not a GpZ) were shot at 12k miles. Ed

put a good set of tires on it & torque the wheel bearings to oe specs it will ride like a new bike

also , dont underestimate the value of balanced tires.

Not to say that front/rear alignment would cause your symptoms, but aligning the rear wheel based on the marks is not always accurate on these older bikes. Look at the article from the KZR filebase Wheel_Align . It is the about three files down and called Wheel_align.

Joe

KZJOE900 wrote: Not to say that front/rear alignment would cause your symptoms, but aligning the rear wheel based on the marks is not always accurate on these older bikes. Look at the article from the KZR filebase Wheel_Align . It is the about three files down and called Wheel_align.

Joe

Good point Joe.

another simple meathod that i use every time i tighten a chain , is to measure from the wheel nut , back to a point on the frame.
on older bikes i start at the swingarm bolt center,and measure back to the axle bolt. just make sure the distance is the same on both sides.