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Kawasaki Z650 / 1100

Discussion in 'Some Assembly Required' started by Bevelheadmhr, Nov 3, 2019.

  1. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    I need another project like a hole in the head, but I was offered the basics (very basic) start of a project as part of a swap, and since it was an old Kawasaki inline 4, with a deep breath I took it on board. This should be my 2020 project, though I couldn't resist making a start

    What I have is a 1978 Kawasaki Z650 frame, a Z1000 tank and most of a GPz1100 motor in pieces.

    If you've checked out the pic below already, you'll have noticed the frame isn't quite as it left the factory. There's a good reason for this butchery, as the frame needs to be widened by about an inch and a half (35mm) to accommodate the GPz1100 motor. Well, I say Gpz1100, but I suspect when we've finished with it it'll be a bigger than 1100cc, as the block is badly scored and needs a rebore.

    It'll be having better suspension, but not USD forks. As for the wheels, I have a pair of homemade 17inch wheels which came off my old drag bike, not sure if they'll make the final build, but they'll do for now.

    I started the project work a couple of months ago, and progress is slow as I have other bikes to finish, but I hope to have it on the road by the summer of 2020.. famous last words..

    Z650part1 020.JPG Z650part1 020.JPG NorleycarstartandJeffvlog 013.JPG Jeffvlogwheels1 008.JPG
    #1
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  2. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    For the swingarm, the first idea was to use an old ZXR monoshock arm, modified to twin shock, with a pair of billet adjusters .. that happened to be going spare. But it needed a lot of work and the result was going to be too heavy. Luckily I was given the arm from a damaged ZRX1200, which was covered in melted plastic, had small hole in one of its braces and had been narrowed at the pivot... Not ideal, but it was free, so I took it home.

    Had the damage welded up and then I cleaned it up in a mates blasting cabinet. My old drag bike donated an as new rear Brembo and a mount was machined up to fit it to the ZRX arm and billet rear wheel.. So far so good, and not a penny spent.

    swingarm2 004.JPG ZRXweldandblast 001.JPG Vlogpart2a 008.JPG
    #2
  3. fast1075

    fast1075 Not a Lemming Supporter

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    There are all KINDS of interesting things in that last picture. Hard to tell for sure, but it looks lake the GPZ block has been bored for bigger cylinders. I hope you are going to a MKII center in the crank/peanut cam chain conversion, or just using a MKII crank. I have seen too many good motors destroyed from hy-vo chains pulling apart. That J model is a good place to start as long as you know the nuances of the differences between the KZ, MkII, and J model. Loved my old KZ bikes.
    #3
  4. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    There was then a delay for a month or so, as I waited for my mates frame jig to become free. Once the front half of the old frame was mounted, the frame lowers had to be cut out and new tubing inserted along with new motor mounts. The rear half got a bigger 20mm pivot (to take the standard ZXR spindle), along with additional reinforcement.

    I've not quite committed to a particular seat unit / carbs / air box yet, so the final finishing touches on the frame will have to wait.

    vlog21a 011 (2).JPG Z650Part7a 004.JPG Z650Parta7 007.JPG
    #4
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  5. Pezz_gs

    Pezz_gs Cant ride for crap

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    This is looking great :lurk

    Can you give us some more details on this little gem in the background. Supercharger coming, maybe?? :norton

    I'm about to embark on a SL175 / CB175 project.

    Capture.JPG
    #5
  6. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    Coming up to date, this is how the frame and back end look.. I don't have a suitable front end yet, except a pair of Gpz1100 38mm forks, which need a complete rebuild. I'd rather fit a pair of 43mm forks, though finding a good pair long enough (31 inches) wont be easy. In the meantime, there is still a lot that can be done without spending too much, such as making an electrics box in stainless along with a set of engine mounting bolts

    The cases in the frame are just there for setting up, they're not the engine I have which is in slightly better condition and is from an early twin shock GPz1100. The barrels of mine engine have a deep score in one bore, so will be taken out to 73mm, I have a decent set of slightly used pistons to suite. As usual its all being done on a shoestring with what I have already and what I can swap with a couple of friends who are heavily into old Zeds.

    Attached Files:

    #6
  7. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    Its based on a CB72, taken out to 400cc with home made barrels and the crank centre has to be moved to. Yes its supercharged (home made case) and will be run on Nitro. Its from a drag bike my mate built in the early 80's and only recently found and of course he had to buy it back and rebuild it with a few updates.
    Here's a couple of pics..

    CB72001 002.JPG CB72001 011.JPG Jeffvlogendpart 006.JPG Jeffvlogendpart 014.JPG vlog21a 001.JPG
    #7
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  8. Pezz_gs

    Pezz_gs Cant ride for crap

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    Thanks

    Thats brilliant!!!!!
    #8
  9. yokesman

    yokesman Long timer

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    early days of the zee, frame needed bracing, kits from yosh, but the suzi handled from the beginning. might want to also see the later frame mods from the factory as the handling wasnt compromised by the 83 hp engine.
    #9
  10. Tanshanomi

    Tanshanomi Your Favorite Uncle Supporter

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    :lurk

    Subscribed.
    #10
  11. DiggerD

    DiggerD DougFir from SuperDuke Days

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    A bud lent me his KZ650 for a Oregon 500 mile one day ride put on by Rose City MC club in Portland Oregon when my Yame SR500 black box gave up the ghost.
    Fell in love with that IL4 and Kawasaki that day. Ditched the SR500 and got me a 1982 GPZ750, unknown to me as a flexy flyer. Get it up to 80mph and hang on, because it would get into tank slappers.
    Sold that one before I killed my self and bought a Kawasaki 600R Ninja. That bike could rail way over triple digits all day long. Even 2 up. It was a 1986 and I put 86,000 miles before I sold it.
    Replaced that with another Ninja but a 750 ZX7, and racked up 90,000 on that one.
    With that under my belt, here is my 2 cents worth of advice.
    Get rid of the round tube frame and find a 1985 and newer perimeter frame.
    My 92 ZX7R has one hell of a stout frame...and you can by them used for dirt cheap.
    Then you would have a good foundation to build from.
    Look at your frame in your welding jig. See the missing paint on the welds at the steering neck?
    My bet it's from flexing.
    Cheers !
    #11
  12. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    In terms of bracing the frame, its already had a cross brace added between the front down tubes, and it'll be getting another behind the carbs. That hasn't been done just yet as I hadn't decided at the time if the engine was going to have a supercharger or not. Its also going to have an additional mount low down behind the drive sprocket, which will work with a outrigger support. Might even get more bracing around the headstock too. BTW the bare metal around the headstock was done deliberately to check for cracks.

    While a newer frame would handle better as stock, this one was picked as its just turned 40 years old. This means here in the UK it doesn't need an annual MOT (inspection) and means cheaper classic insurance etc. I have other newer bikes if I find the handling of this one not good enough for the road, then again the older I get, the faster I was...
    #12
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  13. DiggerD

    DiggerD DougFir from SuperDuke Days

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    Yea, I thought you were trying to keep it old ...looking...for a reason or two.

    Just remembering Ill handling flexy flyers....:p3rry

    Cheers!
    #13
  14. yokesman

    yokesman Long timer

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    Talking of bracing a 900z frame not a 650.
    #14
  15. fast1075

    fast1075 Not a Lemming Supporter

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    The flexy-flier GPZ-750 is strange. I owned one, rode many in the course of doing my job. Built and raced a turbo. There were two that handled funny. Both had sacked steering head bearings, and worn out/unserviced forks. Both handled fine after repairs and new tires. Raced a KZ-650. Raked the frame and did all the frame/swingarm/wheelie bars myself. Went straight as an arrow. Ran 145mph in the quarter with nitrous. At that power output, the engine was not reliable. Left stock, the 650/700/750 is a very durable engine.

    I finally got fed up with the durability issues caused from the elevated tune, and switched to a KZ900 based machine. I started out with a KZ900 frame and swapped the forks, swing arm, wheels brakes, etc over and built a power ringed high compression 1075 that I ran with a progressive nitrous system, and MTC slider, throttle stop, Schnitz Racing Pro Mod controller and a Biondi triple hit box. I set it up to run 10 flat at most events. Throttle stop off the line, sputter at 100 ft. The competition would blow by me at 330 thinking I broke. At about 500 feet the sputter would turn off, throttle stop open and nitrous come in. 100% of a 125hp shot by the 660. Almost invariably they would lift to make sure they didn't break out, and I close on them at about 145mph. Some times I would go to a tune and test and sandbag all night until someone wanted to run for money. It was fun and exciting. It would run mid 8's at near 170mph unleashed. I bought nitrous in bulk.
    #15
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  16. baldman1

    baldman1 Long timer

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    Cool project. The 650 / 750 frames are very stout and don't require bracing. I've done this same swap several times but didn't have to widen the frames. The engine fit with about 1/8" clearance on both side. Did you try the engine in the frame before cutting it up?
    Here is my last one with a worked over 82 GPZ1100 engine.
    [​IMG]
    [​IMG]
    #16
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  17. villageidiot

    villageidiot Long timer Supporter

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    #17
  18. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    The frame was cut before I got it, but the main problem is the lower front engine mount, it doesn't align with the frame mount. The easiest way to deal with this is the cut out and replace a part of the lower frame rail. We did this to the frame, but another reason for widening it was to allow a wider modern swing arm / wheel to fit. Again this is possible without widening the frame, but means spacing out the top shock mounts. Something my mate (who did the frame mods) didn't want to do, as it looked 'wrong'. Cutting apart the frame was a bit extreme I thought, but my mate has built a few frames from scratch, so it wasn't a big deal for him.
    #18
  19. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    That's a cool turbo, I had an MTC big bore turbo Zed for awhile, it had a scary homemade nitrous kit too. It was for a time one of the fastest street bikes in the UK back oldphotos 008.JPG in the early 80's. I bought it as a restoration project after it sat in a damp garage for 30 years. Turned out the engine and turbo were toast, and I reluctantly parted it out..
    #19
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  20. Bevelheadmhr

    Bevelheadmhr Been here awhile

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    Will do, not much progress in the last few days, except I spent £10 on a 60cm length of 316 marine grade stainless bar. This has now become one of the engine mounts. My friend owns a real machine shop and keeps an old Capstan lathe for odd jobs, he let us use it to cut the threads on the bars (made all the engine mounting 'bolts'). It uses a cool spring loaded die which springs apart when the thread is cut to the correct depth. Cant recall the name of it, but great bit of kit, probably made in the 1950's, you can see it attached to the capstan on the extreme left of the pic.

    Pic from my phone so a bit blurry..
    20191105_112517.jpg 20191105_112517.jpg
    #20
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