Honda cg 125 k1 engine cutting out when I wind throttle back

[Kelly.]

Hi, I'm new to this but I'm desperately wanting to know why my Honda CG 125 K1 1977 is giving me trouble. The engine is cutting out when I wind the throttle back sharply, it's ok when wound back slowly and runs ok but in need of an emergency I need the engine to respond to the throttle promptly. I've tried changing the jets, fuse, battery and adjusting the points, coil and timing but still no change. It winds back properly on full choke.
Any suggestions??

Cheers!

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Kelly.

[Pol Anorl]

air and fuel mixture set right?
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[Kelly.]

Yes done all that, can't think of anything else what could be causing it
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Kelly.

[Mysteriass]

"Cutting out"

Do you mean to say the engine actually dies (Electronics issue?) or just bogs/splutters (Fuel issue?). Does it recover or die if you keep the throttle on?

How about when the engine is hot and you've done a few miles, is the problem any "better" then?

If it's spluttering under load then maybe you've got some crap in the fuel tank that's partially blocking the petcock filter or has worked its way through and clogged the fuel pipe (like fat in an artery leading to a heart attack)

Screw your petcock off, or at least take a look in the tap bowl and see what state that's in. If there's anything in there then something warm and wet should make that happy.

Old fuel that can't ignite fast enough?

It might be expecting 4* fuel and the modern unleaded just can't burn fast enough for the 1970's timing/points gap causing a "flood"? Try some octane or lead replacement. That's a guess though and on review I doubt this is the issue as the problem would more likely to be "knocking" or "pinking".

[Pol Anorl]

so you need

original jets
correct needle
make sure airbox is connected with correct air filter
make sure you have no air leaks on any of the rubbers
turn the mixture screw all the way in then 2 1/2 turns out

from the description you gave its bogging down under fast full throttle.
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20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

[Kelly.]

All those have been done and double checked, the bike idles perfect and is fine when on choke but if I take the choke off and pull the throttle back sharply the engine dies and then I have to start it back up.. If it's winded back slowly it's ok. Just had carb in bits and its now clean as a whistle and still not joy
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Kelly.

[WD Forte]

I'd go with what PaulFzs says,
sounds like you need to triple check it.
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bikers smell of wee

[Pol Anorl]

ok so its chucking in too much fuel.. is the correct needle fitted?
air screw set correct?
rubber perished?
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GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

[unitynotsocri...]

Assuming you have the original carb,not the type two Brazil with the accelerator pump,then it sounds like a knacker or wrong main needle.another problem can be float height,..or...a punctured float. You said you needed loads of choke so you either have air leaks, worn main jet n slide , slidecoiver screw misthreaded or knackers engine.
What's clear about every Honda single 125\100 is they need hardly any choke, its clearly a fueling issue..........or........completely worn engine.

Bear in mind that most carbs over twenty five years need a new washer\ jet\ needle and slide and float.
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