Random high revving during stop

[dontgiveajack]

While at a stop and in first gear, my 2009 Ninja 250 will shoot up to around 4000 RPM and stay there. It isn't until I let the clutch out a bit (engaging the clutch a bit), it drops down back to 2000 RPM. I've even shifted into neutral while it is revving high and it stays stuck there.

What could be the issue possibly? I've searched "sticking throttle" but that's not really what's happening.

TIA!

[jay-d]

Is it carbureted? Is this happening at operating temperature or when the bike is cold? Maybe your throttle cable needs adjusting and if it idles at 2,000rpm, that seems a little high and your idle needs adjusting as well.

This doesn't seem like a big issue, just some minor adjustments, but a little more info could pinpoint the problem.

This should also be in the Technical forum.

[absolute]

check to see if you left ur choke on, after ur bike is warmed up. the little lever on the left grip of ur handle bar

[rich6969]

try adjusting your idle screw...

[ZX600]

check to see if you left ur choke on, after ur bike is warmed up. the little lever on the left grip of ur handle bar

This

[dontgiveajack]

I never use choke to start up but I'll double check when I get home that it's completely closed. Is it good practice to use choke even though she starts up without it?

This high revving happens at operating temps. When coming to a stop in 1st gear and clutch in, the RPM's are already at 4000.

When this is happening, I'll close the throttle till it won't turn anymore to make sure the throttle isn't sticking but the RPM's stay at 4000 until I let out the clutch a tad to the friction zone. Only then it goes back down to 1500-2000

[SANI-SAAB]

try adjusting your idle screw...

this

[mindactivated]

I'm surprised I haven't seen this posted more often. I see so many riders with this same problem. Particularly cruisers with straight pipes...

...okay I'm done now.

[dontgiveajack]

Thanks for all the suggestions!

I'm just wondering though... if it was the idle screw, why would the RPM's drop back to 1500-2000 after I let the clutch out a bit then back in again? If the idle screw is the culprit, shouldn't the RPM's stay at 4000 at every idle?

[steve220s]

As previous posters have said, you probably need to adjust your idle screw. It is located on the left side of the bike (see pic). It is probably set to idle too high. When the bike is at normal operating temperature, adjust this screw until your idle reaches approximately 1700 rpms if I remember correctly. You'll notice that you will probably need to use your choke from now on for those cool mornings.

[ZX600]

As previous posters have said, you probably need to adjust your idle screw. It is located on the left side of the bike (see pic). It is probably set to idle too high. When the bike is at normal operating temperature, adjust this screw until your idle reaches approximately 1700 rpms if I remember correctly. You'll notice that you will probably need to use your choke from now on for those cool mornings.

the iddle screw would make the bike Rev high consistently

[mindactivated]

I never use choke to start up but I'll double check when I get home that it's completely closed. Is it good practice to use choke even though she starts up without it?

This high revving happens at operating temps. When coming to a stop in 1st gear and clutch in, the RPM's are already at 4000.

When this is happening, I'll close the throttle till it won't turn anymore to make sure the throttle isn't sticking but the RPM's stay at 4000 until I let out the clutch a tad to the friction zone. Only then it goes back down to 1500-2000

Do the rpms stay at 1500-2000 after you let out the clutch for a bit and then put it back in?

If it's a carb'd bike, when's the last time they were clean?

Also, does it stay at 4,000rpm or does it go down to about 2,000rpm and then when you come to a stop w/ your clutch in it shoots back up?

What would happen if you would slow down in 1st and just slow down naturally? Would it not go below 4k?

[dontgiveajack]

The RPM's stay at 1500-2000 after I let the clutch out a tad and back in again.

Bought bike used so not sure when the last time they were cleaned. I've been hearing lots about Seafoam...

I'm trying to remember when the 4000 RPM occurs most..... I think most of the time, she's at a normal 2000 RPM when coming to a stop. Then, when I hold in the clutch and am about to put my foot down to stop, the RPM's shoot up to 4000. Again though, I want to make clear that when this happens, I'll let out the clutch till point of friction, then hold it back in and my idle is back to the 1500-2000 point.

[Bermuda]

As previous posters have said, you probably need to adjust your idle screw. It is located on the left side of the bike (see pic). It is probably set to idle too high. When the bike is at normal operating temperature, adjust this screw until your idle reaches approximately 1700 rpms if I remember correctly. You'll notice that you will probably need to use your choke from now on for those cool mornings.

Idle on the 250, at least per the service manual for my 08, is 1300-1400.

[Brian P]

Thanks for all the suggestions!

I'm just wondering though... if it was the idle screw, why would the RPM's drop back to 1500-2000 after I let the clutch out a bit then back in again? If the idle screw is the culprit, shouldn't the RPM's stay at 4000 at every idle?

Because the ignition box significantly advances the ignition timing just above normal idle speed, and because with the notoriously lean slow-jet settings on the carburetors on those, if the idle speed is set a little too high then it can get to a point where it starts drawing extra fuel through the main and needle circuit thus resulting in a situation where if the engine is spinning at 4000 then it will stay there, but if forced below the RPM at which both of those phenomena have an effect, it'll stay down.

Just turn the idle speed down a little, you have it set too high.

[espro]

I'd like to chime in here and say that I experienced the exact same issue on a DRZ400SM. Bike was running fine until I brought it in for service to a certain someone. I never figured out the cause of it, but he also overfilled the oil and dangerously over inflated the tires he put on. I know he adjusted the idle screw so that could have been the source as others are saying.

Just to reiterate what the original poster was experiencing, it had nothing to do with choke, you would come to a stop in 1st and clutch in and the revs would climb as if you were giving it a bit of throttle. If you let the clutch out a bit to put some load on the engine, the revs would drop to where they should be, and then you could disengage the clutch again and the idle speed would stay put.

[theassassin]

any indication that the previous owner might have done work inside the bike, like a filter or jet kit??.....a couple of things come to mind here. Could be an intake leak where the clamps haven't been seated or tightened properly on the intake boots, float level too high, not enough slack in the throttle cables, jet needle keeper not installed correctly in the base of the throttle slide on top of the jet needle allowing the jet needle to move up and down on its own. These are the most common things I find causing these problems. As previously mentioned, your bike benefits greatly from a bit of richening up off the bottom. I do this without installing a jet kit. Minor adjustments but still a good 2.5 hours of digging, which produces night and day differences for rideability.

[Wingboy]

Bent,kinked or misrouted throttle cable?

[SLaP]

I noticed in your first thread you mentioned you were buying a 2009 Ninja 250r with an aftermarket exhaust. This is the same bike?
Which aftermarket exhaust? Full or slip-on? Re-jetted/shimmed by the previous owner? What other mods were done on the bike?
Do you have any other symptoms, other than the idle spiking? How frequent does the spiking occur?

So finally, this year I decided to DO IT. I'm getting a 2009 Ninja 250 Limited Edition Green. ~8000km, aftermarket exhaust, frame sliders, rear tire stand: $3500 with safety.

I would first adjust the idle to the setting as per the manual, and see if the bike idles better. Report back.

[frekeyguy]

the iddle screw would make the bike Rev high consistently

NO It won't....under load the RPM will drop.....