CG backfiring and not running properly

[Monkey boi 89]

I have a problem with my CG 125 it keeps backfiring and not running properly so I took the spark plug out and it was black like soot so I change the spark plug and it runs it run fine for five minutes and it's doing exactly the same again I took the spark plug out again and it's black like soot its was a brand new spark plug I do not know what the problem is can you help me please thank you

[fastbob]

I see we have two CG 125 posts running at the same time.Could the answer lie in the other post perhaps ? Any little bits of plastic missing ?

[savo318]

Just a thought, but I went through similar problems with mine, Bad performance, kangaroo, black spark plug. Turned out my air filter needed changing. I'm probably wrong, but take a look anyway, it's always good to be able to eliminate something.

[TimR]

Nowt to read here

Edited July 25, 2017 by TimR

[RantMachine]

Yeah but Monkey boi is asking a new question at least. No doubt [mention]Stu[/mention] [mention]Hoggs[/mention] or [mention]rennie[/mention] will do some chopping and changing if it's an issue

+1 What savo said, if the spark plug is black it's running rich so it probably isn't breathing right. Give the air filter a look - if it's a paper filter just replace it as savo said, if it's the reusable foam type then pop it out and give it a clean then re-oil it. There's a guide on here (isn't there always?): http://hondacg125.awardspace.com/servicing.htm#Air-Filter

Don't go too crazy when oiling the filter or the excess will pool in your airbox and leak into the tool compartment!

AFTER you've done the air filter (not before or you'll just throw the whole thing even further out of whack), check the idle screws are set right. Again, the awardspace site has a guide to getting them back at their factory settings - from there you can tweak them a little if necessary but it'll certainly help you get things back on track if you take them back to stock. It only takes a few seconds and you don't have to take any bits off the bike, so I'd say you may as well do it even before testing the bike to see if the air filter sorted it.

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

And then finally change that plug! If that doesn't sort it then maybe something more is afoot, but I bet that'll cover it

Unless the spark plug is black from oil fouling. It's not black and wet, is it? Because that would be really shit

[Stu]

Thread split

[Monkey boi 89]

I took my CG to the local motorbike shop and they're saying my bike needs new points putting in so going to give that a go and see if that works thanks all

[RantMachine]

Erm... would that cause the issues listed at the top? Anyone? [mention]Stu[/mention] who knows everythingexceptwherenottousegravy?

Sounds fishy to me but the disclaimer in my signature goes double for electrical stuff

[Mississippi Bullfrog]

tbh my first thought would be points - I had one did that. Invest in the puller do the job, I had all sorts of pullers and none of them shifted it until I bought the specific CG tool - then it was a doddle.

It helps to say the year of the bike when asking questions - later ones didn't have points.