Tank Slap ??

on the 77 ltd 1000 recently went on a trip, with the gf and luggage bag on the bike it wanted to tank slap REAL bad when I was turning and with a slight uphill in the turn, when going down and turn everything was fine.
Is this a geometry issue with the added weight of the luggage on the rear or is there something else going on I need to look at?
The bike has invader wheels, duel disc on the front, the rear tire prob only has 1000 miles on it the front tire has prob 3000 on it. After looking at it after the ride home I did notice that the front tire is starting to cup just a little bit this may have started on the trip.

Any ideas would help

Thanks

fork oil level equal?

leon

I would be checking preload on the steering head bearings and make sure your tire air pressures are correct for the higher weights.

When was the last time you replaced the main steering bearings? It could be any one of a number of issues from tire pressure to wheel bearings to crappy front forks springs to low/uneven fork oil.

Also, I had a brand new 1977 KZ1000A1 that was prone to tank slappers...most often when taking off from a dead stop into a turn..and this didn't really clear up until I sold the bike.

I copied this from a post from Jeff Saunders(owner of Z1 enterprises)

Motorcycle Wobble Causes

There's a LONG list of potential area that can cause this.

These are not in any particular order
Wheel bearings
Steering bearings - repack grease, check tightness
Swing arm bushings/sleeves/bearings - replace is worn, repack grease
Fork springs aging - check spring length
Unequal fork oil - if seals leak, then your damping can be ineffective
Rear shocks aging, damper leaks - if you have oil leaking from the seals, the damping is toast.
Worn Tires/Mismatched tires/tire pressures/wrong size tires
Wheel alignment - don't trust the chain adjusters - I visually align the wheels.
Bent rims/broken spokes - get the wheels off the ground and spin them - check for runout / damage
Front disc warped - check for runout
Steering & swing arm bearings are very common problems, but so are tire issues (pressure/mismatch) and wheel alignment.

From www.kzrider.com 650ED

Here’s how I was taught to balance a tire/wheel. Put the axle through the wheel bearings and suspend each end of the axle on something high enough to keep the tire from touching the floor (I use ice chests because I don’t have bar stools :laugh: ). Give the tire a gentle spin – it should rotate freely for a while before stopping. When it stops put a small piece of masking tape on the wheel at the 12:00 o’clock position. That is the lightest side of the wheel/tire combo. Give it another spin. When the tire stops spinning the masking tape should be at the 12:00 o’clock position again. This verifies that is the lightest spot. Tape 2 separate 1/2 oz. weights where you marked the light side. Spin the tire. When the tire stops spinning if the weights end up at 12:00 o’clock replace the 1/2 oz. weights with 2 slightly heavier weights – maybe 3/4 oz. and try again. If the weights end up at the 6:00 o’clock position trim a little equal amount off each on and spin it again. When you have found the correct amount of weight the tire will stop at different positions each time you spin it.

Now here’s why you use 2 weights. You now need to move one weight 60 degrees to the left of the spot you marked as being light and move the other weight 60 degrees to the right of that spot. Tape them in their new locations and spin the tire. It should stop in a different location each time. If not; adjust both weight a little but by equal amounts until it does. Once you reach the point where the tire stops at a different place after each spin mount the weights in those positions.

By moving each weight 60 degrees away from the light spot you have created 3 points on the wheel that balance it out, the original heavy spot and 2 weighted spots, and these 3 points are evenly distributed around the wheel – each is 120 degrees from the other. If you only use a single weight and place it 180 degrees away from the heavy spot you create a barbell effect that is not desirable. Ed

Thanks for the help, I did replace the steering head bearings with tapper type a couple of years ago at the same time I replaced the wheel bearings and the front tire.
I did notice on the last PGR ride I did running solo that its starting to do it without the load and the front tire is starting to show some cupping.
With that being said looks like its time to replace the tire and recheck / replace the bearings and rebuild the shocks.
should cure the problem I hope

Bobby