cupping on buffalo front tire

[two-stroke-brit]

when i got my bike the front tire was allready worn unevenly.
and one fork seal was blown and the rear shocks were shot.
what causes cupping? .
is it bad front springs or headstock bearings or leaking oil seals or something else .
or all of the above
i have replaced the rear shocks,forkseals,wheel bearings.
i am waiting to do the headstock bearings and will replace the front springs with a progresive set soon.
i am going to replace the wheels and tires and dont what to find i have ruined a fresh tire by missing something simple out.
thanks mark

[Craig380]

the tyre could've been badly mounted by the previous owner, too.

Does the bike fly straight when you take your hands off the bars?

[Coyote]

When I got my GT550 it had a strangely worn front tire. Sort of all off one side with a high ridge in the center. Upon removal, I discovered the forks were bent. They were actually kinked right at the lower tree and about .030 out of round there. So the bike was involved in a front ender sometime in it's past.
Next time you have your forks apart, lay your tubes together on a bench and roll them against each other to check them or you can use a pair of V-blocks and a indicator to check them individually.

[rbond]

Also one of the classic causes of 'cupping' is incorrect tire pressure.

[stevegt738]

Also one of the classic causes of 'cupping' is incorrect tire pressure.

Especially noticable on dual sport bikes with their recommended low tyre pressures.

Mark, with the list of problems your bike has, I don't think your tyres had a chance. But at least your fixing them. When you fit new tyres, use the pressures recommended by the tyre manufacturer, not Suzuki. I run 34 /36 psi front & 38 / 40 rear depending on load.

[two-stroke-brit]

the tyre could've been badly mounted by the previous owner, too.

Does the bike fly straight when you take your hands off the bars?

no its like a dog shaking after getting wet.

[two-stroke-brit]

Also one of the classic causes of 'cupping' is incorrect tire pressure.

Especially noticable on dual sport bikes with their recommended low tyre pressures.

Mark, with the list of problems your bike has, I don't think your tyres had a chance. But at least your fixing them. When you fit new tyres, use the pressures recommended by the tyre manufacturer, not Suzuki. I run 34 /36 psi front & 38 / 40 rear depending on load.

thanks steve will do.

[Craig380]

If it shakes a lot with hands off the bars then it could be the head bearings, or the forks are out of true.

This could be worth trying: slacken the front wheel spindle nut, and the pinch bolts on the LOWER fork yoke (bottom of the tree) and then bounce the front suspension up and down several times. Then with the bike still upright, tighten the pinch bolts and wheel nut back up.

If that doesn't help, something may be a little bent, I'm afraid ...

[two-stroke-brit]

Thanks everyone , I am waiting on headstock brgs , but wil check out the fork tubes for bend when I strip It .
I did change out one tube before because of corrosion .
I will post when I track this down.
Cheers mark

[tz375]

Mark,

Did you spin both wheels to make sure they are both round and that lateral play is within limits? As was suggested, start with teh manufacturers recommendations for air pressure. I'd be surprised if they are quite as high as modern bikes which use tires with a very different construction.

[stevegt738]

The tyres that are available for the GTs are still bias ply, but if you run them at Suzuki pressures (high 20s from memory) they feel like they are flat. Bridgestone, Metzeler and Dunlop all recommend a minimum of 34psi for a bike around 220 / 240kg rolling.

Now Radials are another story, but I don't know of any that fit GT wheels. I've changed from radials to bias ply on my DL as I could not get used to the way radials tip in so fast, always felt like the front was about to fold under. The Bridgestone BT45 feels a lot more consistant and stable, it is also the same tyre that is on my GT.

My personal choice for the GT is Metzeler Lasertechs, ME33 front, ME55 rear. Light steering, good all round grip & great milage, but very expensive here. The Bridgestone BT45s are almost as good & a lot cheaper. The edge grip is better than the Metzelers, and the Dual compound rear gives as good milage. Metzelers are more forgiving with tyre pressures than Bridgestones. Please keep in mind that these are my observations from owning my bike for 22 years & over 400,000kms, other owners will have different requirements / preferences. I still ride mine hard in corners & demand more from tyres than most old bike owners. The flexi frame can make life interesting, but damn it's fun scaring your makes on their modern stuff with that big hinge in the middle .

Mark, just re read your first post with all the stuff you found wrong and noticed an omission. Considering how worn out everything is, you better check your swing arm bushes. If they're knackered you'll have some real interesting antics with your bike, don't ask me how I know .

[two-stroke-brit]

The tyres that are available for the GTs are still bias ply, but if you run them at Suzuki pressures (high 20s from memory) they feel like they are flat. Bridgestone, Metzeler and Dunlop all recommend a minimum of 34psi for a bike around 220 / 240kg rolling.

Now Radials are another story, but I don't know of any that fit GT wheels. I've changed from radials to bias ply on my DL as I could not get used to the way radials tip in so fast, always felt like the front was about to fold under. The Bridgestone BT45 feels a lot more consistant and stable, it is also the same tyre that is on my GT.

My personal choice for the GT is Metzeler Lasertechs, ME33 front, ME55 rear. Light steering, good all round grip & great milage, but very expensive here. The Bridgestone BT45s are almost as good & a lot cheaper. The edge grip is better than the Metzelers, and the Dual compound rear gives as good milage. Metzelers are more forgiving with tyre pressures than Bridgestones. Please keep in mind that these are my observations from owning my bike for 22 years & over 400,000kms, other owners will have different requirements / preferences. I still ride mine hard in corners & demand more from tyres than most old bike owners. The flexi frame can make life interesting, but damn it's fun scaring your makes on their modern stuff with that big hinge in the middle .

Mark, just re read your first post with all the stuff you found wrong and noticed an omission. Considering how worn out everything is, you better check your swing arm bushes. If they're knackered you'll have some real interesting antics with your bike, don't ask me how I know .

thanks steve yup i have choice to make with the swinger , i got an ali one from a gs1100e and have to make some changes if i am going to use it but either way i will end up with fresh brgs.
and thanks again for the useful info on tires ,
greatly appreciated.
cheers mark

[stevegt738]

No worries Mark, we're all here to help.

Tyres are like oil, everyone has an opinion, & I'm very opinionated . The trick is being able to give your reasons for what you like about your preference. As I stated earlier I'm very hard on tyres, so grip and cornering feel are important to me. I also ride all year round so wet weather performance is also a consideration. Now if you are a fine weather rider that just cruises along, then some of cheaper Asian brands might suit better. The cost savings alone can be good if you just like to tootle. Shinko tyres have a reasonable reputation for budget tyres. Some Asian tyres also have copied the tread patterns of the good tyres from the '70s & '80s too, good for that more authentic look. I've not had any recent knowledge of budget tyres, so maybe some one that has can chime in with their thoughts on them. Might give you some more options for the way you like to ride.