Making a Kawasaki Z1 race ready. Again

here is some memorabilia...enjoy!
the first ever Superbike race;



in some fast company, look at the several eventual world champions on factory bikes;



and a photo from the starting tower of that 1982 AMA race, match the riders to their bike number;

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wow....mad respect

i cant read em though they claim deleted or moved to ph bckt ect.....

how did manage to stay in one piece...even good Z's crash some....unreal...go faster yet still too....unreal times...just sick....wow

I was under the impression that a boxed swing arm wouldn't be allowed on a Kz in the AHRMA.

DoubleDub wrote: I was under the impression that a boxed swing arm wouldn't be allowed on a Kz in the AHRMA.

authentic period items are allowed

can u explain the theory behind the larger diameter steering neck ? i assume it adds rigidity? not being an engineer, i find it hard to understand why this helps. i would have thought the flex occurred behind it? it seems like the neck itself would be pretty rigid, and the arms around it would flex? why do the tapered bearings help ? the modern bikes still come with round rollers.

I can't speak to the larger diameter neck, but regarding the tapered roller bearing vs the ball type consider the following:
Tapered roller bearings give much more bearing surface area than ball bearings. Think of the bearing contact area of a tapered roller as a "stripe" for each roller that goes from one end of the roller to the other where the roller contacts the race. Then consider the bearing contact area of a ball as a single small "spot" for each ball where the ball contacts the race. The total contact area of the roller bearing "stripes" is much greater than that of the ball bearing "spots." This additional contact area spreads the load reducing the pounds per square inch of pressure at the contact area and eliminates the "dimpling" that is common on ball bearing steering stem races. This reduced pressure also makes tapered roller bearings last longer than ball bearings mainly because the races are much less affected. The reason is easy to visualize when you consider the roller bearings making contact with the full width of the bearing races compared to the ball bearings running in a single line near the center of the races. I highly recommend using tapered roller bearings when replacing steering stem bearings. Having done so on my KZ650-C1; I can attest to the fact that the roller bearings are dead smooth and feel more solid than the ball bearings. Ed

i understand that ed, and for that reason i use them myself. funny though , that the modern bikes still dont use them. since they are wheelie machines, youd think they would.
i'm thinking there must be a better reason for a racer to use them though. like maybe, since they are tapered, the tolerances in the play may be easier to achieve and maintain?

you are both right and wrong to an extent, just need to know history better

during 70-80's tappered were a common improvement for the often undersized stock ball bearings and improved road holding and longevity.

then in the mid 80's the big four went pretty much with tapered rollers from stock, all my gsxr's from the 80's-90's have tappered b's from stock

its only in the last 5-6 years that balls made a comeback in supersport bikes, but these are much sturdier that the old ball bearings of the 70's like in an old Zee, somehting like 55 mm external daimeter. the idea is that they improve steering feel compared to rollers. these new bearigns are very big and will not fit in any old frame. so for most of us tapered kits is still a reasonable improvement, unless you change the steering tube

Thanks for posting! That head is wicked!!!
Later, Doug

My philosophy on the treatment of the big Z1..."Treat her like a queen while in the shop, then treat her like the dirty whore she is while on the track"

Having said that, the drastic braking forces, fast and heavy bike, and lots of wheelies challenge the steering bearings to the point that they need replacing every season.
A larger diameter head uses a bearing with more rollers...more surface area of bearing on race, also a larger diameter steering head lessens the mechanical advantage of the forks on the steering neck.
Think of the forks as a lever trying to force the neck to move. a modest diameter change in the already relatively small steering head yields a great change in the leverage ratio.

what is most entertaining and telling for me....what is old is new again..hats off to the other land masses...but we seem to have the original deal here...a ray of light shined on KZR.....the old is new again.....good bikes but our friend seems to have good gene pool too....those other riders may have had better backing on those old time sheets...but it seems the true legend is the one who goes and goes and goes



notice the overall set up and stance as this beuaty changes and chases the times....simple bike and intense engineering leading to a U.S.A version of a go fast Z...rules dictate flow to a degree..small at that....but this bike...from even early shots....Z usa

the basic lines of the greatest series of bikes ever produced to date...change little...blurr your eyelids and the bikes lines and curves are still in the same places..one gets weekend glory and one can win daytona.....the wheel here...the tubing bent as such...the rider picks the adjustments and throw and pulls....and off you go to do what these bikes have did on every land mass.....walk away.....

i see many more stories here....to me as a KZ Rider for 3 decades.....this deserves more than a welcome...but the seat at the head of the table,.,,,pics...scan em...stories...tell em....lies....you wont need any...your bike and creds are as good as any i have ever seen on this site and i await a chance to learn and absorb more history....know that all you share will be in the books for good now

thank you a lot

Craig....3 miles from the corkscrew...and a place to tune it and camp...tri tip and tacos...GP