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My son's 1991 Honda CG125 worked fine, it's sat dormant in the garage for a few months as his KTM Duke is getting ridden now.
I went to ride the CG yesterday but: it wouldn't idle & spluttered in the middle of the rev range which it was unable to pull through. This got worse and I returned it home in limp mode after about 1/4 mile.
I'm thinking carb, maybe start by squirting cleaner straight in via the air filter and of taking a look at the spark plug.
Help please!
almost certainly carb related - likely to be a blocked jet or similar - strip and ultrasonic clean.
Make sure mice haven't moved into the airbox!
It doesn't have an air box, just a mesh thing.
I don't have an ultrasonic cleaner - will carb cleaner spray work?
it’s sat dormant in the garage for a few months
It'd be worth putting some fresh petrol in as an easy first step.
Try some comma petrol magic. It’ll be gummed up. You’ll need to empty the tank & float bowl and get fresh petrol in there. I bet if you were to decant the petrol in the tank out it’d settle out into layers.
If that doesn’t work and you’re at the stage of taking the airbox off and squirting carb cleaner at the jets it’s probably actually time to give up and wire out the jets.
wire out the jets.
If you don't have any fine wire available, a piece plucked from a wire brush tends to work well.
I stripped and cleaned the carb on my honda c90 a few weeks back, it had developed a leak. First time i had tried anything like that and just used carb cleaner to clear everything. It wasn’t that difficult but it’s handy to have somewhere level and clean to do it and containers for all the bits - not on a lawn like i first did!
I’d seen a lot of videos on youtube at 2Vinatge who does a lot of carb stripping and that was quite useful.
I would put fresh fuel in and strip and clean the carb.
Be careful using steel wire to clean brass jets, people often oversize them. I normally just soak in carb cleaner and blow them out with compressed air. Honda manual sometimes does specify the wire size for cleaning carbs, eg 0.3mm pilot jet etc.
Worth bearing in mind you can buy a brand new CG125 carb for £15 delivered.
Have a look online and there will be service guides, youtubes videos etc if you are not sure on how to.
Whip the carb off, be methodical when you disassemble it. Clean it.
It's very satisfying when you improve things like that.
Any adjustment screws, wind them all the way in and count the number of turns. When you put them back in, repeat and count back the same turns out.
I recently did the carb on my little vespa and it improved it no end. Really pleased with that.
I used carb cleaner and unwound a strand of wire from some bike gear cable and gently poked through the jets and blasted out with cleaner.
An old toothbrush and a soak with cleaner to clear the float bowl etc.
Have a go.