Front Tire "Bounce"

Good Morning
We recently completed a restoration of a '75 Z1-B 900, We held off on the paint thinking we would assemble the bike first, do a short series of "Shake-Down" runs and fix any minor problems then take it back apart and paint.
Very Glad we did that, we encountered several minor and one major problem.
Minor ones were , one of the Air Adjustment screws on the Mikuni VM28's had damaged threads, it works but want to replace it. Hoping someone has one they can spare
Had a couple minor oil leaks , no biggie on those.
My cousin who helped me on this project is both a Master Machinist and Master Mechanic, we have been working on it since March. took so long because of $$$$ Time and we wanted to make SURE it was right each step of the way.
So heres the Major problem.
I have front end "Bounce" almost like a slight basketball thing at all speeds.
The one thing I did not go expensive on was the tires instead I chose "Kenda" brand for front and rear from a retailer , Stock size , an inexpensive tire. Also got new tubes and liners at same time, On my cousins balance machine it was very close to not needing any weights and we used the "turn the tire on the rim method" to more closely align the balance
So here is what we did ,do so anyone who has thoughts about this problem it can please pass them on to me.
New tapered roller Steering Head bearings Z1E
front ( and rear ) Outer Rim is quality piece from Z1E
Spokes ( front and rear) are Stainless quality pieces from Z1E
When we assembled the wheel , we used the lube that was furnished and we were very meticulous in fiollowing the manufacturers instructions , took our time and we spent a couple days rather than a couple hours triple checking the rims.we used a dial indicator to check run-out vertically and horizontally , checked the "Tune" of the spokes as suggested by manufacturer ,got them within just a couple thousandths as checked by dial indicator, ( Very very Close) most tires are not even that accurately made.
Has new front bearings, Quality pieces from Z1E
rebuilt Caliper and new brake pads Z1E
new front fork seals and boots
New rear shocks, new chain and sprockets Z1E
Many, Many, Many other new parts
It does not "Shake" as in a bad balance in front tire, nor "Wobble" it is definitely a "Bounce" in front end.
Where the Rim was welded together by manufacturer we did notice a very slight imperfection ( Dip ) in the way it was welded / joined but that did not present as significant / reflect on dial indicator after assembly.
Anyone else had this sort of problem?
Any thoughts on these "Kenda" tires? Or had a front end "Bounce" problem? Oh yeah EVERY fastener on the bike has been "Torqued" to MFG specs.
Thanks
ED

What weight is the fork oil?
May need a heavier weight.

My Z1B I just finished had a front end bounce like you said. I still haven't balanced my wheels yet, but the slightest bit of the tire not seating properly will cause that. Check the runout on the tire itself and you might find a spot not seated 100%. I had that problem on the back tire.

For the front, I eliminated 90% of it by just servicing the forks. I used the amount the service manual calls for but used ATF fluid. Takes 20 minutes tops.

Used regular Fork oil; approx. same viscosity as ATF,
We are sure tire is "Seated" properly, tire has 28PSI tire pressure,

Check the runout of the tire itself.

I just put a "Kenda" on the front of my bike, no hop here. I wonder if it could be a weak or broken fork spring, 1 side having less spring pressure? Besides checking the run-out of the tire its self, you have covered everything.

Thanks!
We cleaned and "Inspected" the fork springs when we rebuilt the front end,No obvious broken springs, one weaker than other? Not sure...Bike had 58K showing on speedo when I got it..? As far as whether we checked the Run-out of the front tire...........can't remember, thats been a couple months.
We did of course check the rim when we were lacing it up
I was a little "Uneasy" I guess is the right word with the way the rim was welded together by MFG. Did not seem to be a good joint / weld to me , but what the heck do I know?
Gonna prolly take the front tire back off, look at it again see if we missed anything.
Feeling kinda embarrassed /sheepish right now because we thought we were so Carefull, Methodical, Meticulous etc. ya know?
I have owned maybe 10-Kaw Z series bikes over the years My cousin as well,in addittion to a few other brands, don't remember any of them having this " Bouncing Issue" its a new one on me!
Thanks Everyone for your input and suggestions!!
ED

ed spangler wrote:

Used regular Fork oil; approx. same viscosity as ATF,
We are sure tire is "Seated" properly, tire has 28PSI tire pressure,

Fork oil comes in 5w,7w and 10w,maybe 15w also.

I have used 5w30 engine oil before as stop gap until I got around to a for rebuild.

ed spangler wrote:

Thanks!
We cleaned and "Inspected" the fork springs when we rebuilt the front end,No obvious broken springs, one weaker than other? Not sure...Bike had 58K showing on speedo when I got it..?
ED

If your springs are original,could they be past thier prime?

The wheels need to be perfectly balanced as the final step of wheel assembly. Of the hundreds of wheels we've changed, never has a wheel not required any weights.

Needs to be perfect, not just close.

Good luck.

ed spangler wrote:

I was a little "Uneasy" I guess is the right word with the way the rim was welded together by MFG. Did not seem to be a good joint / weld to me , but what the heck do I know?

Did you buy those same P.O.S. stainless steel rims off British Cycles on Ebay? I got suckered into that crap too. I had to send the rear rim back after hours of messing around with it.

I decided to toss those over the winter (learning lesson) and get some OEM rims rechromed.

Those rims suck! I can tear down and relace TWO MX wheels with Excel rims before I could finish truing one of those SS jobs.

One more thing, did you line up the dot on the tire with the valve stem? That dot indicates the lightest spot on the tire.

Also, in case you miss your other thread, I have that ground wire you need coming on a pair of stems I just bought.