misfiring at 3000rpm - Kawasaki Ninja 250R Forum
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post #1 of 11 (permalink) Old 02-14-2013, 10:19 PM Thread Starter
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misfiring at 3000rpm

hey all,

my 2012 250r is misfiring at about 3000rpm.

its got about 2000kms on the clock, so not sure what could be wrong.

i realised it was idling a lot higher than what it should have been since the old owner had it, so i adjusted that to what normal idle should be.

if he had it set 2000rpm for 2000kms could it have done any damage?

any help would be good !

cheers

Last edited by Tricknx; 02-14-2013 at 10:34 PM.
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post #2 of 11 (permalink) Old 02-15-2013, 05:23 AM
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What are the circumstances in which your bike is misfiring?
Is it stalling or acting like it wants to die?
Does it happen every now and then or all the time at other rpms.?
Does the tachometer act funny?
Is it more like a popping noise on deceleration or acceleration?
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post #3 of 11 (permalink) Old 02-15-2013, 05:39 AM Thread Starter
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Popping noise on acceleration

Can feel it in the revs just revving it in neutral

Can feel it sort of catch while riding as well
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post #4 of 11 (permalink) Old 02-15-2013, 05:54 AM
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Any carb or exhaust mods?
Does it happen when the bike is cold or warm?
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post #5 of 11 (permalink) Old 02-15-2013, 06:13 AM Thread Starter
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Any carb or exhaust mods?
Does it happen when the bike is cold or warm?
Nah it's all stock

I let it warm up

Gave it a bit of a rev, noticed was idling higher than what it should be, and the high idle has been the case since I bought the bike, adjusted the idle, and noticed it missing revving up to 4000 and letting it drop back to idle

This was also the case before I adjusted the idle
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post #6 of 11 (permalink) Old 02-15-2013, 07:06 AM
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Usually popping on accel is indicative of an exhaust leak. The Ninja 250 has CV carbs which are basically vacuum operated. When trying to crack the throttle wide open there is a slight delay in response, especially in the lower rpm range.

Other than the popping does the bike drive OK?

Of course you know the Ninja 250 is a carbureted bike and carbureted vehicles have a hard time adjusting to temp changes unlike EFI. So instead of the engine having the right air-fuel ratio for the temp condition, the temp needs to change for the right ratio and proper combustion.

When the Ninja 250 is cold it doe not like a lot of abrupt throttle inputs, so you may notice some sluggish throttle response.

The amount of time it takes for a engine to properly warm up depends on several factors especially in a carbed engine. (fuel used, altitude, ambient temp, humidity and tuning) Every bike and situation is different. Today it may take 5 mins. to warm up, tomorrow it make take 8 mins.

The best indicator that the engine is sufficiently warmed is when it is able to idle steadily at the point in which it was set and is able to pull smoothly just off idle.

Most carbed engines, even when warmed, will not idle sewing machine smooth. There will almost always be a slight variation, bump or hiccup here or there, especially on fuel systems that are gravity feed (such as the ninja 250).

I would check to make sure you don't have an exhaust leak around the exhaust manifold (there have been incidences of those bolts vibrating loose).
If you think the bike is truly misfiring, it may be an electrical problem. Be cause you have so little miles, you may then want to take it to kawasaki and immediately have them fix it if it is still under warranty.

If you want to continue troubleshooting, here are some other things that may help pin point the problem.


Poor Running at Low Speed:

Spark weak:
Battery voltage low
Spark plug dirty, broken, or maladjusted
Spark plug cap or high tension wiring trouble
Spark plug cap shorted or not in good contact
Spark plug incorrect
IC igniter trouble
Crankshaft sensor trouble
Ignition coil trouble

Fuel/air mixture incorrect
:
Pilot screw maladjusted
Pilot jet, or air passage clogged
Air bleed pipe bleed holes clogged
Pilot passage clogged
Air cleaner clogged, poorly sealed, or element missing
Choke plunger stuck open
Fuel level in carburetor float bowl too high or too low
Fuel tank air vent obstructed
Carburetor holder loose
Air cleaner duct loose

Compression low:

Spark plug loose
Cylinder head not sufficiently tightened
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/groove clearance excessive
Cylinder head warped
Cylinder head gasket damaged
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)

Other:
IC igniter trouble
Carburetor not synchronizing
Vacuum piston doesn’t slide smoothly
Engine oil viscosity too high
Drive train trouble
Brake dragging

How Constant Velocity Carburetors Work
http://www.motorcycleproject.com/mot...bs_work_v3.swf

Motorcycle Carburetor Theory 101
https://docs.google.com/file/d/0B8nS...eDg/edit?pli=1
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post #7 of 11 (permalink) Old 02-15-2013, 01:55 PM Thread Starter
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Thanks for all the info !

It is still under warranty but I'm going into the workshop on Monday to have the warranty transferred to me . Hoping they do it .

I mean it does still ride fine

Is it still ok to ride or can I damage the bike ?
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post #8 of 11 (permalink) Old 02-15-2013, 04:30 PM
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Quote:
Originally Posted by Tricknx View Post

Is it still ok to ride or can I damage the bike ?
As long as it's not smoking, leaking, rattling, clanking, banging or throwing flames out the exhaust exhaust you should be fine. Make sure you you the choke when starting it.
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post #9 of 11 (permalink) Old 02-15-2013, 05:10 PM Thread Starter
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As long as it's not smoking, leaking, rattling, clanking, banging or throwing flames out the exhaust exhaust you should be fine. Make sure you you the choke when starting it.

should i take the exhaust cover off to test for the leak?
what section should i check for the leak?

i doubt it is, the bike seems to run fine will riding though.

i dont need to use the choke if its already warm though correct?

sorry first bike !

thanks heaps for your help !
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post #10 of 11 (permalink) Old 02-15-2013, 05:40 PM
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Quote:
Originally Posted by Tricknx View Post
....what section should i check for the leak?

....i dont need to use the choke if its already warm though correct?

Check where the exhaust mounts to the engine.
No, you don't need the choke if the bike is warm.
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