ninjette.org - View Single Post - '10 Ninja 250 Not Firing on One Cylinder...

fallerd · October 20th, 2014, 06:46 PM

I'm at my wits end with wrenching tonight. I bought a crashed, non-running 2010 ninja 250 (3900 miles), and have got it 3/4 running now.

When starting the bike, it will only start and then idle high (3k+ rpm) with the choke full on, and both cylinders will fire. If you back the choke off, the RPM's will drop, and below 2500 and the right cylinder will stop firing, and then the idle will drop below 1200 and the engine will stall and die. If at any point you open the throttle during any of this, the engine will bog and die (though if it is idling with choke above like 5k rpm, I can get more revs from the throttle, but it is very laggy in revving up and back down). From what I can tell, the left carb and cylinder function normally, but can't maintain idle and revs on its own (fiddling with the idle screw doesn't really change anything).

I've drained the tank and carbs and started with new 91 octane fuel. I've pulled the carbs a few times now, once to clean the jets and needles (no change), then once to clean the mix screws and re-set to default (2.5 twists out). Both carbs fill with fuel no problem. I have not synced the carbs, but I didn't get the impression that this would have that large of an effect on such a low-mileage, previously unmolested bike. I have also not pulled all of the tubes off the external parts of the carbs, but made sure that carb cleaner was coming out every internal hole that I could find related to the jets, and this wasn't mentioned in any carb cleaning articles on the Wiki.

I've pulled both spark plugs, tested the coils outside the engine for spark (all good), and swapped them with no change in running behavior. Airbox/filter seem to be normal.

Basically the bike has been running in this condition since I brought it home - everything I've done to it has slightly improved its running/starting, but nothing has solved it.

So, does anyone have any ideas as to things I may have missed or what to do next?

Things I haven't done yet: carb sync, valve adjustment/check, compression test (though no smoke comes out when it runs both cylinders at high idle, no oil in airbox).

October 20th, 2014, 06:46 PM	#1
fallerd ninjette.org newbie Name: David Location: Denver Join Date: Oct 2014 Motorcycle(s): SFV650, EX250J Posts: 7	'10 Ninja 250 Not Firing on One Cylinder... I'm at my wits end with wrenching tonight. I bought a crashed, non-running 2010 ninja 250 (3900 miles), and have got it 3/4 running now. When starting the bike, it will only start and then idle high (3k+ rpm) with the choke full on, and both cylinders will fire. If you back the choke off, the RPM's will drop, and below 2500 and the right cylinder will stop firing, and then the idle will drop below 1200 and the engine will stall and die. If at any point you open the throttle during any of this, the engine will bog and die (though if it is idling with choke above like 5k rpm, I can get more revs from the throttle, but it is very laggy in revving up and back down). From what I can tell, the left carb and cylinder function normally, but can't maintain idle and revs on its own (fiddling with the idle screw doesn't really change anything). I've drained the tank and carbs and started with new 91 octane fuel. I've pulled the carbs a few times now, once to clean the jets and needles (no change), then once to clean the mix screws and re-set to default (2.5 twists out). Both carbs fill with fuel no problem. I have not synced the carbs, but I didn't get the impression that this would have that large of an effect on such a low-mileage, previously unmolested bike. I have also not pulled all of the tubes off the external parts of the carbs, but made sure that carb cleaner was coming out every internal hole that I could find related to the jets, and this wasn't mentioned in any carb cleaning articles on the Wiki. I've pulled both spark plugs, tested the coils outside the engine for spark (all good), and swapped them with no change in running behavior. Airbox/filter seem to be normal. Basically the bike has been running in this condition since I brought it home - everything I've done to it has slightly improved its running/starting, but nothing has solved it. So, does anyone have any ideas as to things I may have missed or what to do next? Things I haven't done yet: carb sync, valve adjustment/check, compression test (though no smoke comes out when it runs both cylinders at high idle, no oil in airbox).