NS125 Jetting/Carb issue..

[badj]

Bike has seemingly been running a bit rich lately, Dellorto PHBH26FS 26mm carb, only idles anywhere near a reasonable speed with the idle screw all the way in (about 1300rpm), any choke kills it instantly, air filter on or off (idle) make no difference, spraying carb cleaner in as per the cans instructions kills it (which to me says its choking full time), and every now and again at traffic lights it bogs down and runs as if its in too high a gear and cuts out, even dipping the clutch and revving it does nothing. It happened a few times yesterday at lights, in 1st, brought the cluch out to bite, went to ride off and it just bogged down and cut out. A few kicks later and a blip and its back to normal. I've cleaned the carb all out a few times but still no change.

It has what I believe to be a full micron system, the needle was originally on its 3rd clip but now is back on 2nd as per haynes specs and it idles slightly better (hardly at all before).

Standard Carb settings are

Jet needle - 2nd clip from top (which its on now)
Float height - 24mm (which seems to be fine)
Pilot Screw - 2 1/8 turns (which i've done)
Idle speed - 1400 +- 100 rpm, which is perhaps around 1200-1400, depending on its mood

Main Jet - 110
Pilot Jet - 48


I've taken it apart now and it has the 110 and 48 jets in it, so it would seem wierd for it to be running too lean, I've got a spare carb which has a 120 and a 48 too. The jetting and exhaust would lead you to think its running lean and misfiring lean, but the plug is a dark brown colour, and the crown looks a bit coked up, and the choke issue etc, plus it pops like a b*tch around 3k-5/6k and it really struggles over half throttle. Contradictory to me?

Any pearls of wisdom anyone can offer? Obviously it doesnt have a powervalve or any of that, no restrictions etc.

[Fortuna]

Check the rubber inlet stump between the carb and crank. It can have hairline cracks and splits that let air in.

[badj]

Had a look, didnt see any issues. I changed the inline fuel filter and put in the 120 main jet, didnt have much issues with pulling away, but anything less than 1/2 throttle and the engine splutters and pops a little, possibly lean? over half throttle and top end of the range its great tho

[SpannerMonkey]

Was that plug reading with a new spark plug?
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[badj]

Yeah, new plug with around 100 miles riding

[SpannerMonkey]

[badj]

It was the first 100 miles I've done on it, previous owner(s) obviously had no knowledge of bikes and had bodged most of it with wrong plug etc. Everything is all hunky dory now, just down to this lower range issue :

[SpannerMonkey]

Ahhh, I had an NS125F before... Please dont say your reg ends in MYX...
It sounds like there is a problem with your idle circuit on the carb... work through all the possiblities, cause no matter how unlikely they are, they're still possibilities
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[badj]

No, its a 125R.

I'm wondering whether the needle needs upping a notch, or perhaps other jet needs upping a little.

[badj]

With the needle down a notch it isnt any different, however I noticed this morning that if I turn the mixture screw in (PHBH26, clockwise turn) the idle raises and it runs a bit smoother. I'm assuming this means it is running excessively rich at idle?