Help with old sportbike..

[japrules]

I am new to sportbiking.. did alot of road course car racing over the years and this is completely different. I have a 1984 Kawasaki GPZ750.. I am just starting to learn how to lean it over and really get into the corners with it.. unfortunately I have found a problem early on.. just as I start to lean into it after the initial turn in (after its already leaned over) the rear end shimmys.. its almost like the rear tire breaks loose for a moment and then catches.... after my heart starts pumping again the bike seems to continue to corner just fine.. but its a less then fun feeling.. its got 10k on the odometer but who knows if its been replaced even thought the title agrees...

I know most of you are not going to know much about this bike but I am willing to listen to theories.. (also, even though its an 84' it is a Uni rear suspension, single shock and spring)..

Also, the only radial tires I can find for these 18" wheels are Avon Super Venoms... any comments?

Joe

[The GECCO]

what is the profile of the rear tire like? is the shape of the treaded area consistently rounded, or is the center area more flattened? I know that some of the tires designed for the older bikes had flatter centers to add to straight line stability and treadlife. when you lean the bike over the transition from the "flat" part to the side of the tire can exhibit the symptoms you describe.

the same thing happens on a modern bike when the rider spends too much time on the highway and wears the centerline of the tire excessively and it becomes "flat".

[Anonymous]

How old are the tires? They may be too old to be leaned over - perhaps new rubber is in order?

[japrules]

I think you have something.. its a real crappy tire.. and yes, the contour is progressive and steep and it looks at though its not meant to be leaned over.. so I need to get new tires..

Checking into new shoes but not much available for 110/90/18 and 130/80/18.. thanks!

Joe

[Dysco]

I think you have something.. its a real crappy tire.. and yes, the contour is progressive and steep and it looks at though its not meant to be leaned over.. so I need to get new tires..

Checking into new shoes but not much available for 110/90/18 and 130/80/18.. thanks!

Joe

http://www.motorcycle-karttires.com/product/Product.asp?group=-1&nameID=4&typeID=5&size=100/90-18

http://www.motorcycle-karttires.com/product/Product.asp?group=-1&nameID=12&typeID=-3&size=130/80-18

I like the bridgestone tirefinder :D

[SuperSport]

Look something like this?

http://gpzrider.lagemann.org/multimedia/GPZ_Members_Bikes/images/image001.jpg (http://gpzrider.lagemann.org/)

I ride an older bike too (not pic).
Click on the pic for a link to a GPZ Site. ;)

[Mr. Turbo]

You might also want to check into metzeler, particularly the ME-55 rear tire. I'm getting one put on my seca turbo, believe me i know the "no grip" problem, so i'll let you know if its stickier than the old ME99 that's on there now.