CG125 stalling randomly

[KuDeTa]

Hey everyone,

Was hoping someone might be able to help me diagnose my 2005 (electric ignition) CG 125.

Tonight i was out riding and after about 45minutes i pulled up at some lights. When i tried to take off the bike stalled, leaving me stuck at the top of traffic looking like a plonker. The only way to get it started again was to put the choke on, without it the engine wouldn't fire. This is the third time it's happened in a week and i'm really confused - clearly the engine is warm enough.


Some advice about what to check would be much appreciated. I'm no mechanic but i do have the haynes manual and have done some fairly basic maintenance on it. The spark plug is about 2 months old so i'm fairly confident that has nothing to do with it.

Thanks,

KuDeTa

EDIT:

https://hondacg125.awardspace.com/idle_screws.htm

Could it it be an idle or mixture problem? I wanted to follow this guide but the guy recommends to warm the bike by doing 10miles at 50mph - no way is that gonna happen in inner city London so i'm not sure how to proceed.

I'm starting to gather that the bike is running way too lean which is why i'm randomly needing to use the choke. Make sense?

[U_W v2.0]

idle speed and idle mixture screw on the carb might be a good idea.

checking the spark plug for colour to determine if its running rich or lean.

pop out the spark plug, snap a photo and post it up on here.

also i should imagine 10/15 minutes idling or 5/10 miles of normal riding in london will warm the engine enough.
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[KuDeTa]

[U_W v2.0]

reference

https://www.apriliaforum.com/forums/attachment.php?attachmentid=196537&d=1341312352

dont forget you will need to adjust your idle speed in accordance with your idle mixture.

higher mixture needs a lower idle speed.

FYI,

the idle speed screw moves in and out along a horizontal axis and has a cone shaped end. this sits at the bottom of the throttle barrel and as you turn the screw in the barrel is lifted upwards by the cone. this adjusts the amount of fuel that enters the carb on idle.

the mixture screw, havent got a clue, all i know is it magically adjusts the air/fuel mix for the mixture ratios lol
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[KuDeTa]

Meh i've left the relevant toolkit with the spanner i need to remove my spark plug somewhere, will have to wait until tomorrow. Ku

[U_W v2.0]

well you've got the above image as a guide.

adjust the idle mixture screw 1/2 a turn in the relevant direction and then adjust the idle speed so it sits between 1000rpm/1500rpm where its most steady.

well, that as a starting point anyway.
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[KuDeTa]

[honda cg 1992]

i have just brought a honda cb250 twin cylinder but it wont revv high and not sure what the problem is can enyone help me please ?

[U_W v2.0]

suggest making a new thread.

post up specific details like "wont rev high" isnt enough information.

"revs up to XXX RPM in nuetral and engine dies" is a more informative post.
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[KuDeTa]

Hiya,

so i followed your advice and took the spark out today. Guess i was wrong because it was sooty and black (Pics: https://imgur.com/a/djhPk ). So it's running too rich right..

Advice about what to do next would be great.

As a side note i wanted to make the bike idle a little faster anyway and when checking the idle mixture screw noticed it was almost all the way in. SO i've undone it about half a turn and the revs are now higher, but as a consequence that means i'm making it even richer, no?

I've checked the air filter and it's fine. Really confused why i am experiencing stalling as per the original post if it's actually running on the rich side - maybe just not idling fast enough?

Ku

[U_W v2.0]

if its running to rish the mixture screw should be turned outwards an the idle speed increased.

the thing to remember with these 2 settings is it will only affect the idle tick over of the bike.

rich mixture - turn out mixture screw, increase idle speed
idle speed will increase the revs and stop it from stalling due to lack of revs

lean mixture - turn mixture screw inwards, lower idle speed.

you will need to clean the spark plug though and check the gap with a feeler gauge. it should be in the workshop manual how big the gap should be.
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[KuDeTa]

I'm a bit confused..

Surely if i let the idle mixture screw out and increase the idle speed that increases fuel... therefore making it richer???

[U_W v2.0]

you decrease the mixture and increase the idle speed if its rich

(decrease mixture turning mixture screw out, increase revs by turning speed screw in)
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