2010 250r starting issues

Ryan Small · March 16th, 2024, 12:03 PM

Hey guys, I’m at a complete loss. I have a 2010 ninja 250r that had been sitting for a while. I installed brand new OEM pilot jets, new diaphragms, and cleaned everything. It has a full battery and cranks well. If it’s sitting for a bit it will fire right away when cranked then die out and not start again. The wired thing is it starts with fluid and stays running/runs amazing and I can ride it with no issues. I have cleaned the fuel filters. Changes the fresh gas and am out of ideas. If anyone has any ideas or can guide me in the right direction that would be awesome. Float height is set to 17mm, needles are shimmed since the snorkel is out and the fuel screws are set to 2.5 turns out on both carbs. Bike has 12000km

Thanks in advance!

Triple Jim · March 16th, 2024, 12:49 PM

Don't use starting fluid unless you want to replace the diaphragms again.

I'm wondering if something is wrong with the petcock, and it's not fully opening during cranking when vacuum is low. Then when you get it running with the starting fluid the petcock opens and stays open. Does anything change if you set the petcock to the "Prime" position?

Ryan Small · March 16th, 2024, 01:34 PM

Hey thanks for the response. I’ve tried cranking with it on the prime unction but it didn’t change anythign. I’ve also tried letting it sit for 30 seconds on prime then switching it back to the in position and cranking with no success. Could there be a vacuum issue or would that cause it to not run at all?

Triple Jim · March 16th, 2024, 01:39 PM

"Prime" is supposed to bypass the vacuum part of the petcock and turn on the fuel flow. You can check that by putting the end of the hose that normally connects to the carburetors into a container and turning the petcock to "Prime". You should have good flow when you do that.

Ryan Small · March 16th, 2024, 01:55 PM

It also doesn’t like to start with the choke fully open which seems weird to me since it seems to not be getting fuel since it doesn’t like to fire without starting fluid. I can get it running but with a large amount of hesitation and cranking

Triple Jim · March 16th, 2024, 03:01 PM

What's the history of valve adjustment? When the valves get out of spec these engines get very finicky to start and don't want to run right until they warm up.

Ryan Small · March 16th, 2024, 03:04 PM

I am not sure! I bought the bike this past fall. Maybe I’ll reach out to the original owner. It has 12000km on it so I assumed that wasn’t the problem but that seems like it could be the issue

Triple Jim · March 16th, 2024, 03:46 PM

It's possible. You can do a compression test and find out. If the valves are not closing all the way, compression will be low.

March 16th, 2024, 12:03 PM	#1
Ryan Small ninjette.org newbie Name: Ryan Location: Canada Join Date: Jan 2024 Motorcycle(s): Ninja 250, KX 250f Posts: 6	2010 250r starting issues Hey guys, I’m at a complete loss. I have a 2010 ninja 250r that had been sitting for a while. I installed brand new OEM pilot jets, new diaphragms, and cleaned everything. It has a full battery and cranks well. If it’s sitting for a bit it will fire right away when cranked then die out and not start again. The wired thing is it starts with fluid and stays running/runs amazing and I can ride it with no issues. I have cleaned the fuel filters. Changes the fresh gas and am out of ideas. If anyone has any ideas or can guide me in the right direction that would be awesome. Float height is set to 17mm, needles are shimmed since the snorkel is out and the fuel screws are set to 2.5 turns out on both carbs. Bike has 12000km Thanks in advance!

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March 16th, 2024, 12:49 PM	#2
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	Don't use starting fluid unless you want to replace the diaphragms again. I'm wondering if something is wrong with the petcock, and it's not fully opening during cranking when vacuum is low. Then when you get it running with the starting fluid the petcock opens and stays open. Does anything change if you set the petcock to the "Prime" position?

March 16th, 2024, 01:34 PM	#3
Ryan Small ninjette.org newbie Name: Ryan Location: Canada Join Date: Jan 2024 Motorcycle(s): Ninja 250, KX 250f Posts: 6	Hey thanks for the response. I’ve tried cranking with it on the prime unction but it didn’t change anythign. I’ve also tried letting it sit for 30 seconds on prime then switching it back to the in position and cranking with no success. Could there be a vacuum issue or would that cause it to not run at all?

March 16th, 2024, 01:39 PM	#4
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	"Prime" is supposed to bypass the vacuum part of the petcock and turn on the fuel flow. You can check that by putting the end of the hose that normally connects to the carburetors into a container and turning the petcock to "Prime". You should have good flow when you do that.

March 16th, 2024, 01:55 PM	#5
Ryan Small ninjette.org newbie Name: Ryan Location: Canada Join Date: Jan 2024 Motorcycle(s): Ninja 250, KX 250f Posts: 6	It also doesn’t like to start with the choke fully open which seems weird to me since it seems to not be getting fuel since it doesn’t like to fire without starting fluid. I can get it running but with a large amount of hesitation and cranking

March 16th, 2024, 03:01 PM	#6
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	What's the history of valve adjustment? When the valves get out of spec these engines get very finicky to start and don't want to run right until they warm up.

March 16th, 2024, 03:04 PM	#7
Ryan Small ninjette.org newbie Name: Ryan Location: Canada Join Date: Jan 2024 Motorcycle(s): Ninja 250, KX 250f Posts: 6	I am not sure! I bought the bike this past fall. Maybe I’ll reach out to the original owner. It has 12000km on it so I assumed that wasn’t the problem but that seems like it could be the issue

March 16th, 2024, 03:46 PM	#8
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	It's possible. You can do a compression test and find out. If the valves are not closing all the way, compression will be low.