250 cutting out when idle

rat_race

This problem came out of nowhere.

Bike appears to ride fine when the revs are up. If I turn the bike on from cold, and let it idle, it's fine for a while...but when it goes down to normal idle speed, it can splutter, (as if a misfire?), as if it's about to cut out...then it might recover and repeat, and eventually cutout from it...

If I'm at lights / idling, I need to get the revs up to stop it spluttering or cutting out. Sometimes it's okay for 30 seconds or whatever when I stop, but always comes back.

It's not the air filter or the battery (tested others), or bad idle speed adjustment.

I adjusted the valves myself a year ago...so they SHOULD be good, unless of course I screwed it up.

I wonder if it's a power thing, maybe a dodgy rectifier or something, where there isn't enough power getting to the plugs at low RPM.

It could be the plugs themselves either, but why only at idle speed? The plugs are only about a year old and are the NGK recommended.

Oil one year old too.

Could be bad fuel too...but again, why only at low RPM? Also, I didn't refuel lately.

Any ideas / tips?

two wheels good

I'd think of fuel and carb first-off too.
I'd start with draining the tank and the fuel bowl and adding fresh fuel. I wouldn't throw away the old stuff! Save what comes out of the bowl to inspect it for crap.
I'd check and clean the plugs too.

pudzey101

What make/model is the bike and what temp does it show when it cuts out ?

My Zx does the exact same if sitting in the one place for awhile or at traffic lights for ages , fan comes on for a minute or 2 and if it hasnt moved itll cut out .

Fuel carbs and plugs are ok so ruled them out .

rat_race

pudzey101 wrote: »

What make/model is the bike and what temp does it show when it cuts out ?

My Zx does the exact same if sitting in the one place for awhile or at traffic lights for ages , fan comes on for a minute or 2 and if it hasnt moved itll cut out .

Fuel carbs and plugs are ok so ruled them out .

It's a Ninja 250. This happens fairly quickly, I wouldn't say "ages" and the fan doesn't come out (not waiting around that long)...

It's fuel injected, so not the carbs

Actually, it hasn't been half as bad the last day or two, so I'm leaning towards bad fuel...but we'll see.

blade1

I'd start with new plugs, clean fuel and a drop of injector cleaner and see how you go.
Can you check what kind of spark you are getting off the plugs?
If they are any bit blue, time for new ones.

pudzey101

blade1 wrote: »

I'd start with new plugs, clean fuel and a drop of injector cleaner and see how you go.
Can you check what kind of spark you are getting off the plugs?
If they are any bit blue, time for new ones.

fuel filter too , could be clogged up with sh!t

b.c

Could be throttle position sensor needs adjusting

galwaytt

any water or condensation in the tank ? If even a bit, the petrol floats on top of it, and you can get all sorts of weird running.

rat_race

galwaytt wrote: »

any water or condensation in the tank ? If even a bit, the petrol floats on top of it, and you can get all sorts of weird running.

I think it might be related to water, alright. Under the cap, there was a little pool of rain water (and dirt!) in the circular groove. Haven't noticed that in the 5 years I've owned this bike...but anyway, it shouldn't be able to make its way into the tank as when closed, the bottom part of the cap should create a seal and prevent of of this water from splashing in. But who knows...

Anyway, problem is all but gone now, on its on accord. Thanks for the help. Pity I didn't solve it myself as it's rather annoying not knowing!