Strange choke issue?

archaeofreak · February 25th, 2015, 10:06 AM

My GF has just started taking the ninja for her morning commute and last time she told me something odd that night. The bike dies whenever she turns off the choke at idle. But, if she turns the choke off while at speed and then comes to a stoplight and idles the bike runs. To clarify, it seems to only die if she turns the choke off at a stoplight when at idle. This occurred first on her commute home in the afternoon AFTER 10 miles of riding, so the bike should be fully warmed up. I have been commuting several times per week for about 5 months without this problem and have not had a chance to drive it since she had this problem.

Is this a simple carb cleaning required case? Any thought on why specifically this would happen? It doesn't make sense to me that it would matter WHEN the choke was removed...only think I have noticed in the past was a slightly bouncing idle that would sometimes drop too low and die in the first couple minutes of idling...eg while getting ready to leave for commute in the morning. Thoughts?

agentbad · February 25th, 2015, 11:14 AM

Sounds like the pilot jets could be dirty buy rule out all the simple stuff like air filter, plugs, and fuel filter before you do surgery on the carbs. Is she leaving the choke on to long maybe?

jkv45 · February 25th, 2015, 01:15 PM

I would look at the idle speed first - it should be idling at about 1300 when fully hot.

Have you removed the caps on the idle mixture screws? That's the next thing I would look at - adjust the idle mixture screws to the optimum setting. 2.5 turns out is a good start. Original settings are leaner.

How old is the gas? If you let it sit with a low level of fuel you could have developed condensation in the tank. Running ethanol-free 87, or the lowest octane you can get without ethanol, is your best choice IMO.

archaeofreak · February 25th, 2015, 03:15 PM

Idle has been adjusted, carbs were cleaned 1000 mi ago (3 months), caps were already prev. removed by prior owner, and were adjusted at same time as carbs cleaned. New plugs, valve adjustment, air filter, oil, coolant, gasket for stator (oil leak), butterfly valve visually adjusted, fuel filter installed (conical in-line) and chain cleaned, oiled and adjusted at same time. Was running fine for last 3 months, until slightly bouncing idle noticed 1 month ago, and choke required for start-up (was not initially).

Ethanol free is not available in my area, but gas is less than 2 weeks old. Always use reserve for about 20 mi after getting fresh full tank, but there is some sediment in bottom of tank, so possibly the filter could already be clogged, will need to check that...if the GF is right about the pattern of dying, it just seems really weird to me, also that the carbs would need cleaning after only 1000 mi...

jkv45 · February 25th, 2015, 03:54 PM

I would open the floatbowl drains, catch the gas, and see if you get any sediment out.

I would also check the settings on the idle mixture screws to see where they are at, just for reference. 2.5 out is the base setting most of the time.

February 25th, 2015, 10:06 AM	#1
archaeofreak ninjette.org member Name: Justin Location: Phoenix, AZ Join Date: Sep 2011 Motorcycle(s): 2007 Ninja 250R Posts: 82	Strange choke issue? My GF has just started taking the ninja for her morning commute and last time she told me something odd that night. The bike dies whenever she turns off the choke at idle. But, if she turns the choke off while at speed and then comes to a stoplight and idles the bike runs. To clarify, it seems to only die if she turns the choke off at a stoplight when at idle. This occurred first on her commute home in the afternoon AFTER 10 miles of riding, so the bike should be fully warmed up. I have been commuting several times per week for about 5 months without this problem and have not had a chance to drive it since she had this problem. Is this a simple carb cleaning required case? Any thought on why specifically this would happen? It doesn't make sense to me that it would matter WHEN the choke was removed...only think I have noticed in the past was a slightly bouncing idle that would sometimes drop too low and die in the first couple minutes of idling...eg while getting ready to leave for commute in the morning. Thoughts?

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February 25th, 2015, 11:14 AM	#2
agentbad ninjette.org sage Name: bob Location: Earf Join Date: Apr 2013 Motorcycle(s): 2005 Ninja 250, 2006 SV650N Posts: 642	Sounds like the pilot jets could be dirty buy rule out all the simple stuff like air filter, plugs, and fuel filter before you do surgery on the carbs. Is she leaving the choke on to long maybe?

February 25th, 2015, 01:15 PM	#3
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	I would look at the idle speed first - it should be idling at about 1300 when fully hot. Have you removed the caps on the idle mixture screws? That's the next thing I would look at - adjust the idle mixture screws to the optimum setting. 2.5 turns out is a good start. Original settings are leaner. How old is the gas? If you let it sit with a low level of fuel you could have developed condensation in the tank. Running ethanol-free 87, or the lowest octane you can get without ethanol, is your best choice IMO.

February 25th, 2015, 03:15 PM	#4
archaeofreak ninjette.org member Name: Justin Location: Phoenix, AZ Join Date: Sep 2011 Motorcycle(s): 2007 Ninja 250R Posts: 82	Idle has been adjusted, carbs were cleaned 1000 mi ago (3 months), caps were already prev. removed by prior owner, and were adjusted at same time as carbs cleaned. New plugs, valve adjustment, air filter, oil, coolant, gasket for stator (oil leak), butterfly valve visually adjusted, fuel filter installed (conical in-line) and chain cleaned, oiled and adjusted at same time. Was running fine for last 3 months, until slightly bouncing idle noticed 1 month ago, and choke required for start-up (was not initially). Ethanol free is not available in my area, but gas is less than 2 weeks old. Always use reserve for about 20 mi after getting fresh full tank, but there is some sediment in bottom of tank, so possibly the filter could already be clogged, will need to check that...if the GF is right about the pattern of dying, it just seems really weird to me, also that the carbs would need cleaning after only 1000 mi...

February 25th, 2015, 03:54 PM	#5
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	I would open the floatbowl drains, catch the gas, and see if you get any sediment out. I would also check the settings on the idle mixture screws to see where they are at, just for reference. 2.5 out is the base setting most of the time.