NSR 125 Low Idle Speed and Dropping Revs

[anthony_r6]

Hi Guys,

My NSR has developed a problem with low idle speed. This is happening when I stop at lights, the idle speed is at about 1k approx and if I stop quickly, I have to slowly (REALLY slowly) twist the throttle back a touch before slowly letting it go again to stop it dying. I also notice in neutral in the morning when I put the choke on it's dying out, but if I hold the throttle back a bit to put it to 3k revs for 20-30 seconds I can take the choke off and it'll stay running. I've had this issue for about two weeks or so, and I can't really remember what it used to idle at in first gear, but I know I never had to rev it to keep it alive.

Any ideas what can be causing this? Now that I've passed my test, I'm okay to work on the bike and replace the things that need doing.

Thanks

Anthony
____________________
Ted : "Maybe he's agoraphobic."
Dougal : "Jack scared of fighting? I don't think so, Ted."

[Mikey CB500]

Had the same problem with my NSR125RR Foxeye, turned out to be the tank had been lifted by the garage when it was in for some work, and the petrol pipe had been kinked when the tank was lowered again.

Could also be a dirty fuel pipe/filter, blocked up carb, blocked air box (where the filter has fallen through)

Definately sounds like something affecting the fuel or air going into the engine.

[Vexon101]

I only have this issue when I don't warm the engine up or accidentally leaving the choke on while driving.

[Avora]

Have you tried adjusting the Idle Air/Fuel mix screw. If you look at the side of the carburettor then you should see (hopefully) two screws one in the middle and another further towards the air box. The one closest to the airbox is the one you want, turn it all the way in and then count 2 and a 1/2 turns out. Try that, and move it about to see if it idles better. Possibly turn the idle up (the other screw) just in a half turn or so.
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Kawasaki AR125 B8 - Getting ready for a summer time soon!

[anthony_r6]

I was thinking about the idle screw and I'll take a look later today. BUt I think Mikey could be right. Thinking about it, I have had the tank up lately and it's quite possible it's got caught or something. Either way I'll have a pop at it today.

Thanks Guys.
____________________
Ted : "Maybe he's agoraphobic."
Dougal : "Jack scared of fighting? I don't think so, Ted."

[anthony_r6]

[Mikey CB500]

Dont have it now but me and my best mate have owned and worked on over a dozen NSR's so know them like the back of my hand.

NSR's wont run for long on the choke if there deristricted, seems runny but they eventually sit there and litteraly get the much fuel or air and flood thereselves. From mine to the main road is a 400 yard ride so started the bike on choke for a minete and then rode it on choke for 400 yards and then turned it off before joining the main road, always used to run fine, and diid over 29K miles on one complete engine, didnt ever rebuild it just used to clean piston, head and powervalve blade every 3 months.

[anthony_r6]

I checked the fuel line and it's not catching, crooked or kinked. I did mess with the clutch cable at the handle side a bit and have managed to sort out the dying by adjusting it.

I've just tried to put my choke on (the bike has been ridden for the last hour-or two) but the engine just dies unless it's got some kind of throttle action on it. For some reason the choke doesn't seem to want to work.
____________________
Ted : "Maybe he's agoraphobic."
Dougal : "Jack scared of fighting? I don't think so, Ted."

[Mikey CB500]

Could be either the choke is seized in the carb, the choke jet is blocked, or the cable is nackered then.

Sounds like you maybe had the clutch adjusted so that the bitting point was with the lever touching the bar thus making the clutch not fully engage which would cause revs to drop when in gear and the clutch lever was pulled in.

[anthony_r6]

The choke is not doing a thing. I had to remove the air filter to see down there. The Carb could do with some external cleaning which I'll get around to soon. My question is, can I damage it by starting the bike without the air filter on? I don't think I can, but I wanna make sure before I do it!
____________________
Ted : "Maybe he's agoraphobic."
Dougal : "Jack scared of fighting? I don't think so, Ted."

[alains]

the choke piston has a convex bottom made with kind of rubber
the piston close a hole and if for any reason it dont the mixture is wrongly too rich causing the engine to stuff and stop
so bugs come from :
- worn piston or spring shapeless
- sharp bends on the choke cable
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the worst day fishing is better than the best day working