CG125, poor running (for 15,000 miles !)

[Paul2129]

Hi, I bought a 10,000 mile CG125, it's a 2005, I've had it for 4 years now and done 15,000 miles. It's always run bad, it doesn't like to run without stopping until it's warm, although it starts fine, when warm it needs revving or with continued idling or it will stop, meaning constant blipping the revs at lights. When coming off the gas at 50mph it 'Bucks', kind of surges, clearly it's bad fuelling. It will also randomly 'blow itself out', kind of back-fire and snuff itself out like a candle (I think it's power output is probably quite similar
So, I sent it to the local bike mechanic, and spent £35 on having it cleaned out, mainly since it was cutting out in traffic. The mechanic said the pilot jet was blocked, it does now stay running better when it's cold, but the other problems remain. In addition, a new problem of it repeatedly revving up, then down again when it's hot.
I'm having a nightmare, any ideas on the cause, or has this just not been looked into properly by the mechanic ? I don't doubt that the pilot jet was blocked, but maybe the investigation stopped there ?
Any advice would be appreciated

[Rob Fzs]

it probably needs a new plug, new air filter and the valves doing, the oil is also suppose to be changed every 1k miles, do all those things and then come back
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Mod 2 Passed 09/06/2011

[Meatybeaty]

Hi Paul , what does the spark plug electrode look like , is it sooty or white

[jaffa90]

4 years 15,000 miles poor running, it`s more than the bike needs looking at, did the mechanic find out or tell you why the pilot jet was blocked?

[Meatybeaty]

Hi Paul, did the mechanic change the "O" ring in between the carb inlet and the cylinder head, they are well known for deteriorating and sucking air , you can never set up the carb that way.

[Paul2129]

Thanks for the replies

Plug has previously been changed, didn't alter anything, valves have t been done, but it runs quiet and happily maintains 65mph, air filter hasn't been done while I've had it, oil has been changed religiously.
I'm not aware that any 'o' ring was replaced

I think this might just need to go back to the mechanic, they didn't take me seriously when I asked to get in back running properly, shame

[redeem ouzzer]

Have you adjusted the mixture screw? Probably why it won't idle when warm.
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Be a REAL MAN!

[Paul2129]

I didn't personally touch anything. I've not touched a carb since the last time, where I emptied an entire tank of petrol onto my garage floor overnight

[Paul2129]

It revs, slowly upwards, maybe over 5 seconds, then the revs drop, and it keeps repeating. I remember having a lawnmower that did this, I never really knew what caused it

[jaffa90]

You have come on here for advice, it would help if you answer!
"did the mechanic find out or tell you why the pilot jet was blocked?"

[Jmh600]

Send your carb off to have it ultrasonically cleaned and set back to base settings....

It just so happens that I've purchased a new ultrasonic cleaner and I offer a strip clean rebuild service. For a single carb (as a complete unit) it's £30 including return shipping, and a 1 day turnaround.
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Jmhmotorcycles

[Paul2129]

Forgive me for not answering, I was told why the jet was blocked, and I can't be sure if that was a standard response, or really the cause. Much of the bad running remains, and the mechanic is currently on holiday, I'll just take it back when I can

Thanks for the advice

[mudcow007]

CG's are simple beasts mine lay in a farmers field for years beofre i bought it an even I got mine to roar (work) again.

Ideally the carb needs to be cleaned (just so you know its clean) an set to default settings

new plug, new air filter, oil etc basically a service

see how it runs after that an go from there

Nice CG website

https://hondacg125.awardspace.com/

might give you some ideas on servicing etc

[chris-red]

Sounds like an air leak to me. Get some easy start or other flammable aerosol and spray around the carb/intake and see if the revs rise, if they do you have an air leak.
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[Paul2129]

I just inspected the air filter, it's pretty clean, however there's some custard inside the airbox, particularly yellow custard, and on the dipstick is some double cream. Maybe the previous owner was a chef, I'm not sure what this means.

Seriously though, I've never seen inside the airbox before, but the water in the oil, I've been cleaning off the dipstick for years, there's not much, and I've no idea how it gets there, other than being caused by condensation from lots of short local running about.

Regarding the comments of 'buy a proper bike', I already have a CBR600, and an NC750X, I find the CG125 is a supreme round town hack, it's seen some serious use and abuse, now it's time for some TLC

[arry]