1992 NS125R Carb Settings

[thomp1983]

Hi first post and im after some advice please. ive got a 1992 honda ns125r. the bike is fitted with a micron exhaust and cone filter from dellorto. i also bought dellorto's jet upgrade kit as listed below as i assumed the bike would be running lean with the unrestricted exhaust and filter. now with the bigger jets fitted the bike runs like a dog, i can get a decent idle and low throttle response but the midrange response is useless and splutters coughs, the top range is ok but could be better. i then refitted the original jets which are

110 main
48 idle
not sure on power jet as can't see marking

with the originals in the bike runs alot better there is a slight flat spot at about 5.5-6k but surely with the original jets the bike will be running lean? what size jets should i fit, i assume the dellorto recommended ones are too big, or quite possibly for the later nsr which uses the phbh28.

also the circlip on the needle is on the second notch from the top as recommended in the haynes, should i be adjusting this to allow for the exhaust and filter, possibly to 3 from top to richen it, i believe adjusting the needle height affect the midrange mostly?

https://www.dellorto.co.uk/merchandise/products_details.asp?PartNo=NSR%20JET%20KIT&CategoryID=2&PartsectionID=24

cheers
chris

[Avora]

Jetting carbs is always going to be a pain if you have no experience. With the original jets in, I would suggest doing some plug chops, and see what the main jet is like. The idle should'nt be much of a problem, simply the idle screw until its evident the jet needs to go up or down. The mid range, as far as I under stand it, comes from the needle jet, thats a quick change around of the circlip to allow more or less fuel...trail and error is the only way. Otherwise I'd suggest that you put the original air box back on, 2 strokes arn't a lover of the cone filters. As other posts on the forum suggest. As I say, experimenting is the only way to learn, a flat spot usually means lean, but google will show up tuning symptoms easy enough. Good luck
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Kawasaki AR125 B8 - Getting ready for a summer time soon!

[st3v3]

When i had my micron on, the bike had same flat spot, gather its normal but i drilled some holes in the airbox (10 or so) then it got better.

Now its stock and boggy but no real flat spot but the carb is untouched far as i know.
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Roger wrote: Women don't get damp for clingy puppies. Get some better happy pills, hit the gym & buy a medallion the size of a dinner plate. Job done

[stirlinggaz]

i didnt think there was a "jet kit" for the old ns?
quite likely you have the kit for the later nsr.....
was normal to fit micron & just drill a few holes on airbox.
no need to change any jets (except for moving the clip on needle)
though i'd be plug chopping for re-assurance.
cheers,
GAZ

[thomp1983]

hmmm had a play around again with this and still having problems. im now back on the stock air box which has some extra holes in it. ive set the needle to the third clip which is one richer from stock and im happy that that's right, the plug is the correct colour. the problem im having now is at higher speeds in 5th and 6th, i can accelerate upto around 60mph in 4th when i kick into 5th the bike will accelerate for a small amount of time then it starts to cough and splutter and the exhaust can also backfire this will not clear with downshifting or differing throttle positions and the bike will just proceed to cut out and will only restart with the choke on, if i leave it idleing a few minutes then it's fine for the first 3 or 4 gears then the problem starts again, any ideas is this a sign of i need a bigger main jet or something else?

is there anyone local to me in north derbyshire (tibshelf) that wouldn't mind having a look or a decent garage you could recommend?

cheers
chris