Crazy question- handlebar rebound

As some have noted(and been beyond helpful) my front end/handling has been a source of woe.
It still feels like crap low speed.

Standard checklist- new everything- tire/springs/seals/bearings/races (allballs, not oem), front wheel bearings "feel" perfect, but they are the last "thing" I believe I could check. fork tubes are as straight as I can tell.

double checked all torque/adjustments etc, all appear to my moderately trained eye to be 'on'
Still very low speed the threat of over-steer is there. And I'm not sure if I'm describing it correctly, feels unstable.

At speeds from 15-30 if I let go the bars, tracks perfect, as a test, I bumped the bar and got wobble, never increased past what I did- in fact, lean forward it went away! ..ok..
At highway speeds, this thing cuts highway. Perfect ride, bit of vibration, but- love it. I almost think I could put my feet up and lean way back for miles.

At low speeds, 0-10 it feels like I may dump the bike by turning the bars too fast, like that terrifying the very first time you got on a big bike and started driving around, each stop with people watching was nerve wracking.
You know- almost like you're just about to oversteer and dump it from turning the handlebars too far/too fast.
However, this is Not my first goat rodeo.
This bike alone almost 2K miles in the last 10 months
AND that weird handling didn't start till I.......replaced everything.

If I'm sitting on the bike, hands off, and bump the end of the bar with my hand, it moves away, and rebounds.. hand moves it away, it comes back to a point, goes half way to where I bumped it, returns, then settles.
almost like I have an oversize under inflated balloon tire on the front.


Thats as accurate as I can explain it.
thanks for reading, and input- CWG

edit: I run the tires nearly max pressure. Dunlop 404s.
After reading a brilliant file on heat/tire pressures, thats where dunlop suggested they should be-(incidentally, that tweak did make a huge difference in the tracking problem I was having. my old standard pressure of 28/30 for the front was FOUR pounds too low. and the bike doesn't want to chase those worn grooves heavy trucks leave in asphalt now)
Rear air shocks near max, as is the front tube, rebound I think is @ 3, 1 or 2 feels like mush and my fat ass kept bottoming out.

My 82 Kz1000 LTD has always been ill at slower speeds. It is undergoing a bit of refinement currently. One problem I've always had is when going over an un-even surface the bike would not track straight.
First last night I did the Swing Arm Bearings, and while I had it off I braced the Arm.
I've also ordered a Fork Brace from Fast From The Past, and it will be here soon. I'm trying to get a fork bushing kit from Race Tech also, but emails go un-answered. Steering head bearings are also coming for it, and hope to gather all the front end stuff and put it all in next week, with the tubes set a bit lower in the clamps. I'm not hoping for a race bike here, just something solid, more steady that can be a confidence builder in the twisties. The 90 Zg Concours I have is like a rock in the corners, solid, and just stays right on track, bumps and all. The KZ would try to kill you at those speeds before, so I hope it will be much improved.
I rode the KZ for a short couple of blocks ride last night and the swing arm felt so much better with the new tight bearings and the bracing. I'm pretty sure that was my tracking issue.

medina,

have you jacked/blocked your bike up square with the wheels off the ground and turned the front end to feel for any thing that feels wierd?
what you are describing sounds like notched steering head bearings.

motorhead,

that braced swingarm will make a big difference in handling.i believe that you will be very glad that you did it.

leon

Set your fork height to stock.

I've had the bike up on bike stand, and it felt perfect.

stock height?? whats the stock height, how far above the top brace should the tube be?
That does sound like my problem, now that ya mention it. I currently have the tube maybe 1/4 or 5/16" higher than the very top of the brace. I poured over the manual and couldn't find an exact number, was going off pics in the book

I know on my KZ650-C1 the top of the tubes are set flush with the top of the upper clamp. Ed

Looks like about 10mm there, try 3-5mm.

If your shocks are adjusted to 100% stiff, try backing them off to 50%.

Took a video, not sure if it shows clearly what I was describing about the rebound.
Dont recall a bike doing this before, even the light 100's125's

Hmm, doesn't really show it, LOL looks more like an angry biker beating on his bike. But when I hit the bar, it goes out, comes back- does this four complete times

I'm laughing at myself for posting this btw..ah, if you cant take yourself not seriously..you're doomed.

If the front tire is on the ground when you tap it like that it will return. I believe what is happening is the tire is flexing as you move the handlebars slightly, but the contact patch of the tire is not actually moving on the ground, so as the tire returns to its normal unflexed orientation it pulls the handlebars back to center.

650ed wrote: If the front tire is on the ground when you tap it like that it will return. I believe what is happening is the tire is flexing as you move the handlebars slightly, but the contact patch of the tire is not actually moving on the ground, so as the tire returns to its normal unflexed orientation it pulls the handlebars back to center.

hmmm, rats..was hoping it was a clue

thanks Ed

CWG

Are the steering neck bearings tapered rollers or new balls in new races like came from the factory ?
Recheck your work. Is the electrical harness binding or possibly a cable ?
Since all bikes dont steer by actually turning the handlebars at speeds above say 10 miles a hour,they steer by force on the bars to carve a turn by leaning into a turn any low speed problem disappears above the threshold where the wheels act like big gyroscopes. Your video was unclear to me as to what you are expecting the handlbars to do while at rest with weight on the front tire. Some bikes test front fork bearings by raising the front tire off the ground and pushing the bars all the way in one direction and seeing how far they move back and forth went released.
As Patton says Good Fortune

going off what SFLTD wrote, how tight did you make the stem bearing preload?

It is a somewhat personal preference, I always tighten just enough so when the bike is off the ground, and I slightly turn the bars, they don't flop to the stops. I wouldn't go any tighter than that. If they are, it could cause the issue you're describing by not letting the bike move freely enough. I experienced this on a friends enduro bike testing out a new steering stabilizer. He had it WAY too tight and I could barely control the bike, just cruising on it. I'm 37 and got my first bike when I was 8, this was the first time I experienced something as weird as that from poor setup.

Get the front wheel off the ground, loosen the top clamp fork pinch bolts, loosen the top clamp bolt and tap the top clamp up with a mallet, just 1-2mm to take pressure off the preload rings. Adjust the preload ring loose till the bars flop from side to side, gradually tighten until it smoothly rolls to one side, or at least doesn't flop. Tap down the top clamp and tighten the top clamp nut.

Adjust your fork height to about 3mm and give it a ride.