Some advise needed on Carb setup I am stumped

[Joshua_]

I have just finished a full restoration on a Honda NH125: bottom & top end, all bearings & seals changed.

I am updating the carb on this 125cc engine as the stock carb was buggered. I am putting in a clone PWK 21 which looks pretty well made. I totally disassembled the carb & cleaned all the passages and jets. The problem I am having is that the engine only runs properly with the choke circuit opened. Otherwise it dies like it is too lean. I have gone all the way down on the clip & am running the richest jet (150) to no avail. I don't seem to have any air leaks. What else could be causing it?


https://ibb.co/ZLZByMk

[Grumph]

Not familiar with that carb - but it should have an air corrector jet and/or an air adjustment screw somewhere.
If you can't go richer on the jets, go smaller on the air side - which will richen the mixture.

[F5 Dave]

I avoid Chinese clone carbs. Sadly I'm often called in to try fix bikes where the owners cheap out because they kinda look like a real carb. The worst bit about then is the fuel delivery to the float bowl. Check that first, including the fuel line and any inline filter.

Think in throttle position only. The mainjet you refer to is for wide open throttle. There are other jets.

[Hugo Nougo]

150 is way past the size a 125 needs, you've either got a dud carb or another problem, 2t oil feed on those was crap, oily plug?. try specialist forums like battle scooters.

[Hugo Nougo]

these guys make good carbs.

https://jrcengineering.com

[husaberg]

Your float level is likely far too low.