Honda CG125 carb settings.

[Guest]

I have a 1979 Honda CG125. Running ok but spark plug quite sutty which suggests running rich.

I have set the air/fuel mixture screw to two and a half turns out. If I set it any less out i.e. making the mixture leaner,

the bike pops/misfires on acceleration. Has new air filter and plug. Is the existing (rich) setting ok or could anybody please suggest any other options?

Any advice is much appreciated.

Thanks.

[GazW]

I had a CG.

Undo your throttle linkage, look at the circlip on the needle, drop the needle to run leaner, raise it to run richer.

Write down all your settings before you start so you have a benchmark.

Clean all your jets.

I would drop the needle to make the bike leaner, then play with the mixture screw.

[Guest]

Hi, if you've not already got the CG sorted, this may help:

As previous poster has said, worth trying one groove down on the carb' needle; that would be the first place to start.

If that hasn't sorted her out, check the following: is your spark plug the exactly correct one for your bike/model year? Sometimes a sooty plug can indicate ignition system problems - no point going through a whole load of carb' diagnosis if the wrong plug is in the bike.

Regarding the air screw, use your current settings as a 'guide' only. I've had loads of Honda 125 singles and have always set the air screw to the position at which the bike ticks over at its fastest point. In other words, set the tick-over screw to a certain setting (normal tick-over speed is fine), then adjust the air screw until the engine either speeds up, or slows down - you want to set the air screw where the revs become faster - then adjust the tick-over screw back to where you want it. (hope that makes sense)

One other thing which can lead to a sooty plug and popping/banging; cylinder head gasket leak. If you keep trying without success to get the plug colour right, it may point to head gasket failure (this caught me out years ago on a CM200).

Hope that helps,