CZ175 bike - everday commuter

Discussion in '2 smokers' started by hzoltaan, Apr 26, 2017.

  1. PSchrauber

    PSchrauber Long timer

    Joined:
    Jan 3, 2011
    Oddometer:
    1,358
    Location:
    Summer: Kemiƶ, Finland; Winter: North Germany
    Very nice wrote up, yes these CZ are great bikes I recently rode also 175cc CZ trials version from 1963, the bike rebuild the engine is overhauled and too little bit tweaked especially carburetor, cylinder and exhaust.
    No 1:


    No 2:
    #81
    MATTY and spokester like this.
  2. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    209
    Location:
    Krakow
    Jeez, I have not been here for ages!
    Sorry folks, changed job, changed cars (more work on them than ever) and simply, writing long essays about the CZ was not a thing i could do at home or in the office.
    :D But now i work from home, so nobody cares if one of my monitors is ADV forum...

    Actually there's been quite some change!
    Laid my hands on a 1977 CZ175 477 model. That is the closes you can get here to the exported models that were sold in UK, USA, etc.
    I figured, that the 477 has different arrangement for crank seals and bearings, and generally were better made, so... when i saw one popping up not too far away i went and bought it.
    The idea was to keep the frame from the red 487 and dres it up as the older 477 model. tank, headlight, so on. Engine was to be refurbished, mated with the new crank and bored cyl from the 487 and e'voila, a running 477.

    And hear this,
    first time in ages i got pretty lucky with buying something off the interweb!
    I wanted to disassemble that engine (it looked a lot better than my battered 487) and use it in my legal frame. (legal as has documents).
    I noticed some green grease like thing in the bearing under the dynamo. Hm... odd. Took off the clutch cover: clean, dry, more green grease...
    Somebody in the turbulent history of the Polish Third Republic probably refurbished the engine and for the want of a drain plug never got around filling it with oil.

    Actually just lifted the engine out and dropped in the 487 frame, slapped on the new cylinder with new piston, installed the electronic ignition, got the wheels trued, and been using it ever since!
    Will tomorrow take some pictures.

    Took it apart last week to see why i get only 70-80km/h top speed and i suspect the 477's muffler. It's welded shut (I mean you can't unscrew the 8mm bolt and pull out the insides) so nobody knows what's inside. I'll try with the muffler from the 487. Also removed an airduct from inside the airbox. I was told by a guy who raced CZs that this is the best and quickest mod you can do. According to him, the metal tube restricted airflow. We'll see. Sure enough, 487 did not have restriction in airbox.

    Anyhow, the CZ lives on, it has changed appearance but otherwise it's fine! :)
    electronic ignition is still a charm, all electrics are new and good. And the yellow-green 477 clothing looks (for me) very cool. The tyre guy installed wider tyres (1 size wider than for 487) which gave me some issues when putting the wheels under the 477 mudguards. 477 has 2-3 sizes smaller rubbers. It's still tight fit, but the difference of the well trued and centered wheels on good rubbers is amazing.


    PS: almost fell on my face when first tested it. Gearbox is upside down, I mean the gears are. Lift your foot for 1st gear then stomp for 2nd 3rd 4th.
    It was weird when i was testing the gears on the bench, they did not feel right... But anyway, engine ran, let's ride it. As I stomped on it to get 1st and popped the clutch it almost stalled, I was like.... damn, this is barely moving, that's very weak...
    then i lifted into 2nd (into 1st in fact from 2nd) and almost went over the handlebars :D
    #82
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  3. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    209
    Location:
    Krakow
    After this season's end (well, for me, that is... I rode enough in snow and cold when i was 20. :D ) i have decided to take a look at the ignition. (it actually stopped one day riding in the neighborhood... turned out to be empty fuel tank. :D... but i managed to start it backwards! By kicking. Most weird. So i suspected ignition)
    As the chinese scooter flywheel and ignition kit has no positioning whatsoever, it happened before that the flywheel simply turned on the crankshaft a few degrees. But when i tested it with a timing lamp it was spot on. (I do not think that any CZ had such a deliberate ignition test in the last 10 years... Marked the flywheel against a mark on the engine casing on TDC, then measured 2.7mm backwards using a plunger dial, marked it there... and paid attention not to connect my lamp to the bike's battery. The chinese voltage regulator killed the lamps power switch last time. I tend to learn the hard way)
    Anyway, spot on, so the problem is not the ignition. But then why it's so damn weak?
    Andy Reid suggested ages ago, to remove the metal pipe from the airbox... done that. Then happened to read on a 2 stroke tuning book (great pdf) and i suspected that my whole cylinder is sitting a mm below where it should be. So Pulled the cylinder, ordered gasket for it, and while at it, cleaned and filed a little inside the exhaust port.
    I'm too chicken to start porting it just yet, plus I wanna see if i can get somewhere near the factory 15hp. No point starting to file away if somewhere i'm loosing power.

    What baffles me for example is how hard to turn the sprocket in neutral... The whole thing should be swimming in oil and there is only 1 seal on the output shaft that should offer some resistance... maybe my gearbox is not put together as well as it could be...?

    I gonna try now with the slightly uglier but definitely cleaned 487 muffler. The one from the 477 is welded shut and i have no idea in what state it is. I'm not yet as desperate to drop it into a bonfire or as someone on this forum wrote "fill it with petrol and ignite" Then go search for it. :D :D
    #83
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  4. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    209
    Location:
    Krakow
    IMAG0160[1].jpg IMAG0161[1].jpg IMAG0162[1].jpg
    #84
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  5. altf4

    altf4 playground psychotic

    Joined:
    Mar 2, 2009
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    devon gb
    nice one.

    btw: if i don't bring the engine of my mz es/2 mz to compression before kicking, she tends to run backwards, too.
    it's become a bit of a reflex now to put the foot on the kickstart leaving the bike. also helps if you forget to switch off petrol ... ^^

    brilliant. write up. keep it coming!

    max ~:)
    #85
  6. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    209
    Location:
    Krakow
    Hm! Interesting. Now that you mention it... when cold starting it always get 3 kicks without ignition before the big kick. And i do not remember when i properly ran out of juice before. Anyhow... putting first gear then starting to roll backwards as i released the clutch was somewhat... unexpected. :D
    What do you mean by putting a foot on the kickstart leaving the bike? I did not get that.
    #86