Help... Carb problem? Pics added

[cypek]

Hi guys. I have a problem. My bike is cutting out when Im riding. It starts ok and tick over is fine when stationary. I would say there is something wrong with carb as choke is also a bit different as it should be. When I switch choke on I can't hear any revs increase but I know it works as when starting bike after being parked a few hours outside I need choke to start it. But I also need to keep revs up by hand. I've tried to increase revs regulating carb but it doesnt help. When I start to ride its fine for a few minutes but then as soon as I engage clutch and release acceleration it dies. I need to stop then, move choke lever 2-3 times and it starts again and I can ride until I want to slow down / stop again. After a few times its getting harder to start it and then it starts dying while riding just like it wont getting any petrol. Any help would be appreciated. Thanks

Oh and bike is chinese 125 with old CG125 engine copy

Edited March 3, 2010 by cypek

[rennie]

well this is a wild guess but I'd say there should be 2 screws on the carb!

1 for idle speed 1 for mixture

I think you've turned the wrong screw!

put it back where it was and start again!

[Pete]

Here's another idea, check there're no air leaks, particularly where the air filter housing meets the carb(s) (Jin knows alllll about this!).

Also what rennie says - put everything back to standard. The idle screw is likely a black plastic thumb screw about the size of a 5 pence piece, the mixture screw is likely to be a smaller "standard" head size that you'll need a screwdriver for.

Good luck and keep us posted

[cypek]

Looks like I played with mixture screw then. But is it normal when I turn it revs will go up? And I didnt really notice any other screw I'll go and have a deeper look I've also sprayed WD40 around air filter box without any result. Also my sparkplug has been changed by previous owner to NGK. Thanks

EDIT: here is marked screw that I played with. Picture is from right side of bike

http://img197.imageshack.us/img197/2559/prawar.jpg

Here is picture from left side of bike. Only other thing that looks like it may be some sort of regulation it knob marked with arrow Maybe anyone else will see something I missed

http://img63.imageshack.us/img63/5277/lewym.jpg

[cypek]

Another picture from top:

red arrow - screw I adjusted; yellow arrow - strange knob??

http://img10.imageshack.us/img10/843/gorao.jpg

Also I checked fuel filter and I dont think its good that its empty inside? Another thing, is it normal there is no any on/off tap under tank? There is some bit with 2 pipes going to carb but it cant be locked? Although when I removed tank, petrol isnt leaking...

[Guest]

Another picture from top:

red arrow - screw I adjusted; yellow arrow - strange knob??

http://img10.imageshack.us/img10/843/gorao.jpg

Also I checked fuel filter and I dont think its good that its empty inside? Another thing, is it normal there is no any on/off tap under tank? There is some bit with 2 pipes going to carb but it cant be locked? Although when I removed tank, petrol isnt leaking...

yellow is choke.

Red Screw is Idle/tickover screw.

tank is vacuum type so 2nd pipe creates overpressure, so tank doesn't drain unless engine is running, hence no fuel when disconnected.

[cypek]

Thanks, than I fiddled with correct screw. Any idea what may cause this cutting out when riding? I have just fitted new fuel filter and as it is clear one I can see petrol flowing as it should on idle but my problem is only when riding

[Guest]

start her up, get the bike warm and off choke, and then applky some throttle, see if it is a stationary of just a riding issue,

if its riding, check hoses to make sure non have become trapped or squashed when you add weight to the seat... could be you are trapping a fuel line and causing a fuel blockage.

i take it you have plenty of fuel in the tank...

[cypek]

Tank is over half full. Well, there was one of them hoses on top of old filter that looked like it was folded in half. Could be that when I sit on bike that hose was squashed even more. But I have changed it for much longer one when fitting new filter just now. Maybe that will solve my problem. When I start the bike it can run for 10-15 minutes without any problem so it seems to be only riding problem. Thanks. Will let you know after work if the problem is still there.

[cypek]

A little update. Well, when going to work yesterday bike felt a bit better. It died 2-3 times but I think that could be due to too low idle set by me. When riding back home on the evening it also died 1-2 times but again, I am unsure as I may not let it warm up properly. I will start it in a minute, warm it up and go for a ride to check.

Also I am not really sure about choke. I still keep my bike in the kitchen so it starts ok when I take it outside but when I'm trying to start it after work I need to use a choke. Problem is I can't just start it as it wont hold revs up on choke. There is no difference in revs when choke is on / off. But when I pull choke while riding bike dies instantly and starts only with choke after my work so it seems choke is working in some way??? I'm so confused...

EDIT: Ok, just had a nice ride and it seems problem is sorted. Looks like revs were set extremely low. When I started the bike they felt like 2-3k (my rev counter lies) and they didn't change after 10 minutes of stationary running. But after a short ride it started dying again and I noticed revs were really low so I turned them up to when it sounds as a nice tickover

EDIT2: Would you say its a bit too high? I would...

http://www.youtube.com/watch?v=m-eWdrfgEcM

Ok, I think I will get the revs a bit down. But woohoo, looks like just some fine tuning left for me and I can enjoy some riding

[Boro Jake]

^ personally i'd say that was too high

[Lumor_uk]

I.ve found it takes a while for a new filter to become saturated enough to let fuel flow freely through it, starving the carb of fuel till it is.

If you've been running the carb off an oldish tank (rusty) might be an idea to spray carb cleaner through all the jets.

Know where you're coming from btw, I've stripped my carb 3 times in a month. In the end i replaced the whole cylinder head and rocker section with a spare engine i.ve got. Was drinking/smoking more oil than petrol. Is perfect now.

[cyberwolf]

is it just me or dose that sound like its tapping badly?

[Lumor_uk]

is it just me or dose that sound like its tapping badly?

 

Just watched the video, was on my phone before, yes it is...really badly.

[Gamer]

you right guys

tapping noise and too high revs(2000 or more - speed with choke on, not idle)

check the OIL LEVEL - top up as i would say thats why it is dying like that (is the engine not getting too hot?) - than verify tapping again (should be more quiet too)

[cypek]

Thanks for your advice guys. All my idle / cutting out problems are sorted. The reason of it was incorrect spark plug fitted by previous owner (gap twice as big as it should be ) and I just adjusted mixture properly and its spot on now Although I agree this tapping noise is pretty loud. I will look at it when I find some spare time.

@Gamer - oil level was ok and I also recently changed it at 700 miles so it definitely is fine:) Also from what I found on internet on CG125 engine choke won't increase revs. (Lumor_uk confirm??)

[Gamer]

Also from what I found on internet on CG125 engine choke won't increase revs. (Lumor_uk confirm??)

 

that's good to know for future

spark plugs

[Lumor_uk]

Also from what I found on internet on CG125 engine choke won't increase revs. (Lumor_uk confirm??)

 

One of the times I rebuilt my carburettor (3 times now) it did, but all the other times like now it doesn't increase the revs and it's running pretty damn sweet at the moment

I think the revs increased when I was missing the pilot screw, had fallen out due to being loose.