Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.


Discussion in 'Bling and Appearance' started by Devery, Nov 14, 2008.

  1. I'll see if I can supply enough information to make sense :)

    I have a CZ 175 from 1973. Its a kick-start.

    The problem I'm experiencing now is; after I start it and get it running, it starts to choke up a bit and eventually I am pretty sure flooding. I'll be riding along and it will just loose its power and when I gear up it just slowly stops.

    I've adjusted the idle screw, as it seemed there was a problem with it idling but now no problem, but it now floods (I think anyway).

    There is also adjustments to the fuel injection that I haven't played with.

    So why is it flooding? Is there anything else I should look at? I'm reading the manual now, I'll post anything that could be useful.
  2. This could have all sorts of causes. The three basic things you want to look to when a bike won't run or stalls are fuel, air and spark.

    I'm assuming the choke is off properly? What does the spark plug look like? It's a two stroke isn't it? - that *might* be relevant here, though I don't know enough about two strokes to know (maybe the oil mixture is at fault? I don't know if you read two-stroke plugs in the same way). How do you know it's flooding? What problem was there with the idling? - too fast? Uneven? For starters, I've found putting carb cleaner through can remove a problem without further ado. Is your air-filter in place and clean?

    Was it riding fine before? Did anything else change about (or was done to) the bike concurrent with this problem?
  3. if the carb hasnt been serviced in a long time, strip and clean it

    i've used nulon carb cleaner when i stripped my carb, be careful when removing float bowls not to round the screws

    maybe find a manual or website specific for your bike, as it might have tips for stripping the carb

    if plugs are black and oily, good sign of flooding just clean them with carb cleaner and a metal brush, to reuse in the mean time

    i've been told not to use something like "start you bastard" in a 2stroke, dont know why, but i dont want to find out
  4. Is it possible to not have a choke? My manual doesn't point out a choke anywhere.

    The idle problem I had was it would just stop when I went in to first gear and still had the clutch in... but didn't do it after it warmed up.

    I have not yet ventured to looking at the spark plug. I have a feeling its not, but it could be. I've adjusted the mixture a bit but the same problem.

    New: O.K. just been looking at the bike... Let me show you in a picture.


    Is that the air-filter? just behind the carb. Because... I was looking at it all and I just touched it and it began to crack and split. Really bad nick rubber. So its now no longer there. I wonder if there was a crack in it already? Anyway... I can't really see whats in the tins behind the opening? I guess the air-filter makes sense...

    If it was cracked could it be the problem?
  5. Also, just talking to a mate now. He seems to think that I might need to increase air flow into the mix. Could this cause it to flood when its warm?
  6. cracked seal/rubber could be a problem, too much air in the mixture... or an airleak..

    see if you can get that sorted first, should be the easiest thing to replace
  7. I imagine I can use any rubber? My dad suggested some push bike tube that we have lying around. I'll give that a go.

    I did open up the carb. Hopefully it all went back in properly! I'll find out tomorrow when I start it up.... If its not going so well, should I just get someone to look at the carb and put it back together again? I think it should be ok, but I'm a little nervous.

    After I get the rubber back on and test with more air I'll check the spark plug.
  8. i wouldnt use push bike tube rubber due to the fact that its very flexible, under load i would assume that if its not held tightly it could get sucked into the cyclinder

    the carb looks simple enough so hopefully you got it all back a-ok

    try cleaning the plugs first before you start it, and then take some after pics of em

    gl with it

    someone here might be able to help
  9. I'll definitely be getting a membership to that community.

    I'll let you know how it goes tomorrow.
  10. Run down....

    I adjusted the air flow and it is running really really well. I also got some new rubber to connect the carb back to the air-filter. I'll post photos of how that went later.
  11. good news, so i guess your plugs are ok tho?

    did you find out in the end what was causing the problem?
  12. In the end I adjusted the amount of air flow so the mist created contained less petrol and that stopped it flooding.

    I have new problems now.. I'll start a new thread, haha!
  13. What rubber did you get - have you found a supplier?
  14. I'll have to show you what I got on thursday. Hopefully its ok, I can't imagine it wouldn't be. But no CZ supplier. There is a club in England :)
  15. That rubber hose takes filtered air from the airbox (behind the side cover/under the seat) to the carbie. Obviously if it leaks here the engine will run lean and may seize. It can be "fixed" by using silicone sealant (use black) and duct tape, but replacement is better.

    If DIYing the rubber tube needs to be fairly thick as the pulses and suction from the engine will collapse thin rubber hose. The seal at each end is important.

    The carbie should have a tickler rather than a choke. Look for a small vertical rod poking out of the top or the float bowl area. You depress the rod for a few seconds to flood the carbie to make it easier to cold-start. If it starts Ok, then don't use it.

    As with all 2-strokes, keep your 2-Stroke oil level up - if pre-mixed with fuel on this bike, stick to recommended settings, over oiling will cause plug fouling, under oiling will damage the motor. It wouldn't hurt to replace the filter and plug as these are more sensitive to fouling on a 2-stroke.
  16. This sounds like critical advice, especially if you're going to go on some long summer rides (where things might go awry and then be so for hours on end, in a context where the bike is running hot anyway). Sounds like it's worth getting a proper replacement rubber asap, and failing that an excellent refurbishment of the old part asap - I wouldn't trust that thin rubber replacement any longer than you have to.

    The other option is to fit a pod air-filter directly onto the carb...
  17. thats a good option if you can't find replacement rubber, just remember you'll need to rejet the carb for the increased air flow