1975 KAWASAKI Z1B

Discussion in 'Some Assembly Required' started by Fast Idle, Apr 5, 2018.

  1. lesman

    lesman Live easy, Brake Hard

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    Did Kawasaki make Bridgestone? Did Bridgestone morph into Fuji/Kawasaki?

    Sent from my Moto G (5) Plus using Tapatalk
  2. poppykle

    poppykle Adventurer

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    Bridgestone and Kawasaki are separate companies but one article I read said that when the motorcycle division closed down the Bridgestone engineers went to Kawasaki and developed the Mach III. My first bike was a Bridgestone 100 Sport with the rotary gearbox. Faster than anything 125 cc and under.
    The 350's were rocket ships in their day.
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  3. RickS

    RickS Long timer

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    Fast idle, he's a photo of the genuine oil can. image.jpeg
  4. Fast Idle

    Fast Idle Since the Sixties

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    Here's some info on Bridgestone Motorcycles I found on the web.

    Not familiar with Bridgestone motorcycles? Here's a brief synopsis:

    In addition to the more familiar tire manufacturing nowadays, the company produced bicycles beginning in 1946, powered bicycles beginning in 1949, and motorbikes from 1958 through 1971. This grew out of an automotive part trading company in Japan run by Soichiro Ishibashi, the company name being taken from a literal translation of his name in English -- Ishi - stone, Bashi - bridge.

    Exports to America began in 1963, via Rockford Scooter Company of Rockford, Illinois (later renamed to Rockford Motors). The first model was the '7', a fan cooled 50cc two-stroke with three-speed rotary transmission. The machines were initially sold via catalogue sales, such as Spiegel and Aldens. Dedicated dealerships were quickly established later on, but never grew to the scale of the other large manufacturers. Small-scale exports to other countries followed, with the bikes not reaching the U.K. and Australian markets until about 1968. The vast majority of motorcycles were destined for the U.S.A. market. The larger displacement models were virtually unseen elsewhere, even in Japan.

    Several Japanese motorcycle manufacturers went under in the early sixties. Bridgestone was doing well and absorbed former employees of failed companies like Tohatsu and Lilac. Out of this came their most well known series of motorcycles, based on rotary valve engines, ranging in size from 50cc to 350cc. This line began in 1964, and were so advanced for the day they continued generally unchanged through 1971. Build and engineering quality reached a new high. In addition to 100% phenolic self-lubricating disc valves instead of the two-piece phenolic/metal seen on other makes (which tended to part company after a while), features included:



    · Close-tolerance chrome-plated bore aluminum cylinders and aluminum pistons (same expansion coefficient)


    · Automatic oil injection (direct to bearings on the 350 models)


    · Rugged and accurate 5 and 6-speed transmissions (needle bearings and no false neutrals)


    · Switchable 4 speed rotary (town) 5 speed return (highway) transmission. (175, 200 models)


    · Dry racing clutch (350 models)


    · Primary kick start -- no hunting for neutral if stalled; just pull the clutch (350 models)


    · Hi output alternators (175, 200, 350 models)


    · Hi output ignition (175, 200, 350 models)


    · Dual-leading-shoe (dual cam) race style drum brakes (175, 200, 350 models)


    · Reversible controls (British vs. Japanese) (350 models)


    · Adjustable suspension (350 models)


    · Rubber cushioned motor mounts


    · Lots of heavy triple-plated (copper, nickel, chrome) plating and candy-apple paint


    · Larger "American" size frame (350 models)


    · No-slip Simul-suede upholstery (175, 350 scrambler models)


    Bridgestone was the most successful marquee on Japanese racetracks in small displacement categories during the mid-sixties, eliciting considerable attention by American riders. This prompted the 'SR' series in 90, 100 and 175cc, which were slightly modified race-only versions of the road-going models. The road-going 175 was enlarged to 200cc in 1970.

    Many of the cutting-edge engineering features found on Bridgestones were not exclusive, but nowhere else could so many advanced features be found in one place. So why did production cease? Many reasons are cited. The advanced engineering and quality came at a price. The 350GTR was introduced at over $900US in 1967. That is $6500 in today's dollars, and was at a time that a basic new Ford or Chevrolet automobile could be purchased for $2000. A Honda or Yamaha of similar displacement could be had for around $700US, which would be equivalent to $1500 less expensive in today's dollars. Though this did nothing to squelch desire it did inhibit sales. Cheaper products are easier to sell to the majority of buyers when the differences in quality are not so apparent just sitting new on the showroom floor.

    While production and profits were doing well, the motorcycle production was more of a sideline to the tire manufacturing. Profits earned didn't stay within the division, but were absorbed by the tire division. Unconfirmed rumors spread that other Japanese motorcycle manufacturers made it clear to Bridgestone that if they pursued their competitive behavior in motorcycles they would find themselves with no OEM market for their tires. Both tire and motorcycle production took place in adjoining sections of the same crowded factory. Expansion of one would be at the expense of the other, unless heavy investment was made in a new factory. The increasing value of the yen vs. the dollar was cutting into profits and didn't bode well for the future either.

    It soon became apparent that corporate interest in continued motorcycle development was waning. Late sixties "new" models were merely warmed over variations of earlier ones. Dealerships began bailing out. Environmentalist pressure against two-stroke engines in the U.S. was also on the rise. Following the 1971 model run, Bridgestone closed the motorcycle division. Most of their tooling was sold to a Taiwanese firm named BS Tailung, which resumed production of replacement parts for previous models, and introduced a series of small motorbikes distributed by Rockford Motors; the Chibi, Tora, and Taka. Virtually all NOS parts available today originated in Taiwan rather than from Bridgestone. BS Tailung ceased operation in 1975.
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  5. Fast Idle

    Fast Idle Since the Sixties

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    So where did you find that?
  6. fast1075

    fast1075 Fasterizer

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    That's interesting!
  7. lesman

    lesman Live easy, Brake Hard

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    Kawasaki and Bridgestone had great ideas in spades but their"stuff" didn't seem to hold together compared to Yamaha. Kawasaki rotary valve bikes looked somewhat similar to Bridgestone. .
  8. RickS

    RickS Long timer

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    Fast idle you be a bad influence. I picked up this bastard thing today. Titled as a Harley but with a Z-1 engine. Springer forks Kawasaki rear section. Motor comes back to a 76 LTD. it’s a period piece (wife says of crap) apparently done in late 70s. It runs and drives but with no front brake and a Goodyear Eagle AT date coded to 76 I am not planning to ride it until fixed. But dang it sounds good 15B17448-CDA9-442E-9A95-DD18B926B3D5.jpeg
  9. Todd157k

    Todd157k Long timer

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    Well, it's not THAT bad. I don't recall ever seeing a frame being bobbed off at the rear of the engine. Like WTF?
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  10. RickS

    RickS Long timer

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    It came out of the old old motorcycle shop in Altus, OK. It was a dealership for about every brand except HD at one time. They sold a boat load of Brodgestones.
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  11. RickS

    RickS Long timer

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    It ou
    it ought to drive the Harley boys nuts! It's kinda strange, but you know, it's cool as all get out.
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  12. Fast Idle

    Fast Idle Since the Sixties

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    That's pretty crazy and you're right about it being cool. Is that a beer cooler under the seat? Looks like it could hold an 18 pack. :drink
  13. RickS

    RickS Long timer

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    I haven't got the nerve up to take the seat off yet. I'm going to take some detailed pictures today and post them in A seperate thread so I don't junk your thread up with my junk.
  14. RickS

    RickS Long timer

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    Or a kilo
  15. Fast Idle

    Fast Idle Since the Sixties

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    The spokes and wheel bearings showed up so I figured it was time to prep the rear hub. It was in pretty good shape. No major scratches or corrosion.
    Need to run them through the parts washer first.
    hub (1).JPG

    The brake plate needs the same treatment.
    hub (5).JPG
    De-greased, cleaned, and bead blasted. Ready for wet sanding.
    hub (7).JPG

    Wet sanding complete and ready for polishing.
    w&F (2).JPG
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  16. Fast Idle

    Fast Idle Since the Sixties

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    Polished and ready for assembly.
    w&F (3).JPG
    Time to lace it up. I like to take a picture of the rims before disassembly for reference.
    w&F (6).JPG
    New bearings installed and ready for truing.
    w&F (12).JPG
    The front hub is still in for powder coating so the front wheel will have to wait. I'll rebuild the front forks in the mean time.
    The left had a serious leak for sure.
    75Z1B (10).JPG
  17. Fast Idle

    Fast Idle Since the Sixties

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    Found some pitting in the left tube when I disassembled the forks so I ordered replacements.
    w&F (10).JPG
    Polished out the lowers when I was doing the rear hub.
    w&F (7).JPG

    New tubes and seals.
    w&F (8).JPG
    The bike had air-fork caps and some after-market progressive springs installed on it. Waiting on stock caps and dust covers to arrive. I'll give this a try but will probably go to a cartridge set-up down the road.
    w&F (11).JPG
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  18. Kai Ju

    Kai Ju Long timer

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    Nice work as always, this bike will look like it just came off the showroom when you're done.
    May I ask where you got the fork tubes ? I assume not oem.
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  19. Fast Idle

    Fast Idle Since the Sixties

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    Thanks. The tubes are made by EMGO. The nice thing about working on this bike is that it was so popular that almost anything for it is available today in a quality replacement. I've had good luck ordering from Z1Parts. Got a lot of the H2A 750 parts from them. Nice quality and reasonably priced.
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  20. Kai Ju

    Kai Ju Long timer

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    Didn't expect EMGO to be the source, even though I got a nice pair of mufflers for my '77 R100/7 from them.
    I guess I need to look at their catalog again.
    My first thought would have been Forking by Franks.
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