CZ175 bike - everday commuter

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

  1. BertieBassett

    BertieBassett RustRider

    Joined:
    Oct 23, 2014
    Oddometer:
    182
    Location:
    Orkney, Scotland.
    666........ IMG_3890.JPG
    #41
  2. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow
    #42
    BertieBassett likes this.
  3. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow
    It seems, like my dynamo is fried. The field coil is fine, but the one on the shaft is earthed.

    there is a set with CDI ignition and 12V stators on the market, for a tad more than what I'd need to fork over for a new coil for the dynamo... That will give me trouble free ignition (the available PAL breakers are crap quality, so every 3-500km necessitates setting of the timing), and I will be able to run H4 headlamp bulb... I think I'll go for it.
    Considering, that it happened only after I came back, I'm damn lucky! :D
    #43
    BertieBassett and spokester like this.
  4. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow
    by the way,
    Can anyone point me to some general guidelines about how to get some extra horses out of the old CZ?
    I mean polishing up the ports and so on. I'm not plannig to take the bike apart and fill it up with low friction magic and so on. :) No, not just yet. :D
    #44
  5. MATTY

    MATTY BORDER RAIDER

    Joined:
    Jun 23, 2014
    Oddometer:
    4,990
    Location:
    England On the Scotish border
    With a little research you may find some, detail port modifications to be able to optimize your power, but in view of what you are going to be doing with this bike exactly how much more HP do you need?
    Now to gain more HP torque etc you can go for the obvious go to modifications, The old saying no substitute for cubic inches is a fair coment, and getting more CCs should get you an edge, i am not sure if there are any popular piston swap and boring out mods for the CZ175s but there may well be, and it might be that the post 2000 CZ180 has a slight increase in capacity over the 175 im not sure of this just guessing but could be worth a look.
    Now other mods increasing compression and easing a few hough off the top edge of the exhaust port have yielded a little power off the more primitive two strokes for me sometimes.
    Taking things a little further you could look at fitting a reed valve this is a little more work but you can do it yourself with a little thought, i am modifying aRTX 212 minsk trials engine to reed valve at the moment yamaha jog reed cage of china construction less than 4quid delivered brand new Making a manifold spacer from a block of aloy but you can make them in mild steel welded construction i have seen it done and they worked.
    Here is a video of reed instal on a minsk just a 125 might give you some ideas i took some inspiration from it on myRTX trials engine mods.
    #45
    spokester likes this.
  6. YamaGeek

    YamaGeek Skeletor sparklemuffin.

    Joined:
    Jun 24, 2007
    Oddometer:
    32,541
    Location:
    western oregon
    The thing about these old school European bikes is that they're great at having a very broad and torquey powerband. It's largely because the piston intake and Schnurle transfer porting tends to be very conservative in their port sizing, transfer and exhaust timing. They are very simple, very efficient and dead reliable, and largely way understressed for their construction.

    Why someone would be recommending that you try to take that wonderful broad power and squeeze it all up 2K~3K into a narrow little power range while ruining the smooth and controllable power delivery down low is beyond my ken.

    There are small adjustments you can do to perk the bike up, mostly cleaning the casting roughness in the transfer ports in the iron or aluminum casting of the cylinder, and maybe with care, and an eye to the ignition timing and mixture, shave a few thousanths off the head to bump the compression ratio a tiny bit. But you run the risk of turning an otherwise easy to kick start bike into a back kicking mess. This is not to mention trying to adapt a reed box and bigger carburetor to a piston ported cylinder never meant for this kind of conversion, and or encouraging someone with very little 2 cycle port tuning experience over cutting his transfer, intake and exhaust ports too far and bolloxing what was a nice running engine.
    #46
  7. MATTY

    MATTY BORDER RAIDER

    Joined:
    Jun 23, 2014
    Oddometer:
    4,990
    Location:
    England On the Scotish border
    I opened my post suggesting if he did a little more research he could perhaps get detailed CZ modification info i then merely gave him very general advice on how he might get a little more power i offered this info because he asked for it.
    #47
    BertieBassett likes this.
  8. YamaGeek

    YamaGeek Skeletor sparklemuffin.

    Joined:
    Jun 24, 2007
    Oddometer:
    32,541
    Location:
    western oregon
    Let's assume he's a little better than a shade tree mechanic.

    You're calling for a skill set with a Dremel cutter, the forethought and metallurgy experience to not create stress risers in any of the aluminum milling you're doing on the piston, not to mention you've just added an inch or more to the position back from the cylinder the carb sits, which messes up the intake tuning from the airbox, requires new plastic fabrication, possibly new throttle cables, the carb sits at a new angle that needs float tuning, the new intake timing from the reeds creates a secondary problem with low rpm flat or rich spots in the carburetion, yada yada.

    Installing a reed box on a bike not designed for one is not 'general advice', especially for a novice mechanic. Nor is milling a piston to change the exhaust timing.
    #48
  9. MATTY

    MATTY BORDER RAIDER

    Joined:
    Jun 23, 2014
    Oddometer:
    4,990
    Location:
    England On the Scotish border
    The OP requested input i gave him input, he gave no Curriculum vitae of his formal qualifications or even brief mention of his experience, i feel we therefore must presume as he asked for advice he must have some idea what is involved .
    I attached the video because i took some inspiration from it in my project which i included brief details of in my post not as a blow by blow cz tunning plan.
    GOOD day Sir.
    #49
    BertieBassett likes this.
  10. neil w

    neil w Been here awhile

    Joined:
    Jan 13, 2013
    Oddometer:
    269
    Location:
    Northumberland
    cz.png Brings back memories learned to ride a bike with gears on one of these belonging to a realtive
    #50
    YamaGeek, spokester and BertieBassett like this.
  11. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow

    Thanks a lot! Once I did indeed read into the reed box solution. (I think that was on an MZ)
    Sorry for guys, for kicking off the bucket with my question!
    Thankfully I'm aware of the project size Matty just suggested. This is a road I can't go down just now, though I might in the future, why not? :)
    My toolkit or knowledge would maybe allow me to do a half botched job of changing the bearings. (no proper tooling to pull apart the engine, let alone professionally put it back together.) So milling the ports is a wee bit beyond me. The idea of checking out the CZ180 is a good one thoguh, with some luck I might find a cyl and a head, put them on and see what happens.
    #51
  12. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow

    Hahahah, I'm just that, a shade tree mechanic!
    This is one of the reasons I like them old Warsaw-pact bikes, beacuse they are incredibly robust and simple. Also, though they are amazingly low power for the cc, that power does come in a wide band. Using it as a get-around bike, I'd not want to swap that for the ass-kicking sensation at 6000rpm. But I'd like to have the option of survival if I strayed on a highway. (which means 90km/h with my carcass and bags :D )

    Your suggestion was closer to what I have in mind, fixing the casting roughness, maybe raising the compression as it is rather low. (but that might be due to already worn rings or so.) The question was theoretical for now. I plan to ride the bike while the weather permits, and take it apart in the winter. And I mean take the cylinder and the head to someone who can do a slight bohring if needed and so on.

    I had a Jawa 350 I rode to UK from Hungary. There I had realised it was loosing power fast and became harder to start, day by day. When I finally pulled the cylinder, I learned that there was an immense play of the piston rod, plus the exhaust ports were almost 3/4 blocked by carbon deposits. A good picture of my riding - slow. Sadly, a mayor engine job was out of question in the UK, it was far cheaper to fish a fairly good Japaneese bike off ebay. So the Jawa, with expired hungarian documents became a love of the past and I rode the GS450 till the mechanic who changed the valve seals broke a bolt and a drill bit into the head.
    #52
    YamaGeek likes this.
  13. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow
    IMG_20170706_132553.jpg IMG_20170706_132618.jpg IMG_20170706_132710.jpg
    Now back to the CZ:

    the generator / ignition components arrived.
    As I wrote earlier, the Achilles heel of those bikes (at least here) is the poor quality of ignition parts available, plus the decades of tree shade mechanics (thanks for the expression) botching the electrics.
    I used to fix the earlier with patience, setting ignition after every 3-4-500kms, and the latter by rewiring the whole thing.
    Indeed, rewiring always worked. It eliminated all the nasty rat-nest of loose wires and insulating tape, and during the process i fixed contacts, switched which were on the edge. So the CZ got a partial re-wiring.
    Then the dynamo died.
    The choice is:
    a) buying a poor quality coil for the dynamo and keep the 6V system with not too good charge and weak headlight (35W halogen is Ok, but nothing when faced by a bi-xenon Audi in a sharp corner)
    b) getting a 12V conversation

    For this I found 2 sellers in Poland and with my meager Polish I gathered that the stuff they sell is not too bad. Some slightly modified chinese-scooter bits.
    If it only makes me able to set the ignition and leave it like that for thousands of kms, plus it makes me able to buy a headlight bulb at a petrol station when needed, it's ok.
    #53
    YamaGeek, spokester and BertieBassett like this.
  14. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow
    Work started IMG_20170704_113843.jpg IMG_20170704_113829.jpg
    #54
    spokester, BertieBassett and YamaGeek like this.
  15. MATTY

    MATTY BORDER RAIDER

    Joined:
    Jun 23, 2014
    Oddometer:
    4,990
    Location:
    England On the Scotish border
    You are getting the parts together for this build and showing a strong commitment to have it done.
    I am sure if do decide you need more performance and you can find out any more info on modifications to this CZ from the more dedicated CZ forums FB pages or specialists, you will get some experienced tunning shop to carry out any modifications you dont feel confident in undertaking.
    It is as i said initially Exactly how much more power do you need that is what you must ask yourself.?
    Guys like this are the type of specialist you need to look for.
    http://stanstephens.com/2stroke.htm

    A good text book to use for your own benefit is this one.
    http://www.vintagesleds.com/library/manuals/misc/Two-stroke Tuner's Handbook.pdf
    As for the CZ 180. i do not know if the CZ 180 is any more than a re badged CZ175, there may however be a slight increase in capacity designation 180 suggests this but could just as easy be marketing .
    But look into it could yield a few CCs and who knows CZ may have done some upgrades and detail mods that improved performance a little, and could well be a straight bolt up swap.
    You need to look on a CZ forum, owners clubb riders club catering for the CZs.
    I am no CZ or jawa expert , but i have 2 decades of IZH PS 350 modification under my belt Planeta Sport 350.. THE DOG Russians call them that is now 400cc conversion and reed valved up with PWK carb that gets the job done and covers 60 plus miles a day TO AND FROM WORK a good % of the time and it has done this around 18 years now so these dogs can hunt if you want them too.:D
    #55
    spokester likes this.
  16. YamaGeek

    YamaGeek Skeletor sparklemuffin.

    Joined:
    Jun 24, 2007
    Oddometer:
    32,541
    Location:
    western oregon
    Back as a teenager, my little Suzuki TS90 got stolen from our carport, and that summer I saved enough to purchase another bike. As it was I was looking for a 175cc or 250cc bike, but nothing but new bikes and or bikes a couple hundred over my limit of $300. A few similar tiddlers were close to my price, but problem was I had already done some work on the Suzi that made it as fast as a stock TS125 and I didn't want a bike that couldn't be ridden on a secondary highways. The Suzuki/Kawasaki shop had a 1968 Jawa 250 with a little over 1000 miles and just broken in, but they wanted $450 for it. It was really impressive how strong it could pull from 2000 rpm on up, But it also stranded me a couple miles from the shop on the test. I decided that it wasn't worth getting when I heard back from a friend, the shop owner had ridden it 40 miles and it stranded him outside of town.

    Luckily a 1967 Ducati Scrambler came up in the local classifieds for $275 with the mention "burns oil". Yeah I lived with the oil burning, it wasn't that bad.
    #56
  17. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow

    Oh wow, thanks! I'll read into that.
    The power I'd like to have... well, having the original factory claimed 15 horses, and 100km/h top speed would be nice. On secondary/third rate roads the usual speed is between 60-90km/h over here, so even packed i did not feel like a moving roadblock. But the bike really did not enjoy 80+ and I'd like it to ride comfortably around that speed. So that even short streches on highways would be possible.

    IZH 350? I almost bought one of those! What is your opinion about the russki casting, manufacturing quality? How often do the piston rods, roller bearings go south? (30000km in a Jawa 2 cyl, and can be slightly more in MZ, CZ, Jawa singles)
    #57
    spokester likes this.
  18. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow

    Hahah, good choice!
    I have a CM200, which was running happily belching blue smoke. You can live with that, agreed. Then I took it to the mechanic, paid for it, and got a bike which is totally fubar'd. Carburettor somehow can't be set, keeps fouling the left cyl. Not Ignition, not compression, not oil-burning, so what is it? ;) Mystery. Hence the CZ, I grew tired of 2 cyl-1 carb-1 igniton mysteries! There's a separate thread for that if you have any ideas. (click here) Poor thing's been parked in the garage untouched for months!
    #58
    spokester likes this.
  19. MATTY

    MATTY BORDER RAIDER

    Joined:
    Jun 23, 2014
    Oddometer:
    4,990
    Location:
    England On the Scotish border
    The CZ is not down on power that much when you look back at typical bikes from that time and similar cappacity, Take the early 1970s Hondas the CB 175 and the utilitarian brother ship the CD175 in British Spec the CB175 was claimed to be 20PS that is 19 and a bit HP.
    And the CD with its single carb head just 17 PS, so the much lighter CZ with 15HP is not that bad a performer, and typical of others back then in its capacity band .
    I think simple mods could possibly extract a couple of HP help it if you see the need, and a good start would be to ensure what you have as standard is all there, clean serviced decoked if necessary and ultimately tuned to perfection.
    Keep your loaded bike to a minimum on weight and load streamlined, and you could well be satisfied with the performance your bike has now.
    The IZH 350 Sport planetas are Made in Japan on the engine Yamaha developed the Motor with IZH, The Russian Made Planeta 5s with their longer stroke motor may well have the issues you mention, i have never seen one of these MOTORCYCLES, only on pictures etc.
    I have Two complete IZH Planeta sport 350s and lots of spares , Engines are robust reliable and perform quite well for a primitive two stroke single, frame is strong handles great, sadly brakes are the big let down in my opinion.
    #59
    spokester likes this.
  20. hzoltaan

    hzoltaan Been here awhile

    Joined:
    Jan 21, 2011
    Oddometer:
    206
    Location:
    Krakow

    The two stroke tuning book you sent is quite a reading! I love the sarcasm in it.
    Regarding the CZ's power: let me have the 15HP available and I'm good. Quite enjoying driving on 2nd, 3rd rate roads with slower speeds.
    I think in the winter I'll check on fixing the imperfections in the ports, cleaning the exhaust (any advice on that? some chemical solution perhaps? Some guys used to ignite the residue in it with a welder and feed it with a compressor till it all burned out... but Greenpeace would probably ignite my roof while I'm asleep the next day!)

    IZH planeta with Japanesee engines?
    Wow, never heard of that...
    You guys got the best of the socialist industry! Hahahha! Yeah, economy needed dollars, so they had to come up with something sellable.
    Do show me a Planeta Sport!
    #60