Irregular idle and stalling at speed

scubaru · May 24th, 2013, 04:52 PM

So I recently purchased a 2005 Ninja 250. Bike is completely stock with a mere 798 miles on it.

The issues are all closely related and I'm sure its probably one fix.

Conditions:
Lebanon, Pennsylvania (elevation 480')
50* with 46% Humidity
Windy with overcast and storms this morning

So the first issue was idle, I would start it up with the choke on and the RPMs would sit at 0, but was still running, if I let the clutch lever out (in Neutral) it would stall it out. Played with the idle controller and got it to stay running.

Once I got it up to operating temperature I played with the idle control again to bring the RPMs to 1500.

Noticed at this point after I let off the throttle the RPMs hold high for awhile then come down.

So I went out for a drive, everything was fine, slight hesitation in the throttle but nothing I would find problematic. Going down a straightaway I hit tops 40 mph, watch my coolant temp drop to within an 1/8" of the bottom of the temp span. Notice my throttle disappearing and suddenly I lose power. Coast to the side of the road and keep trying to get it to stay running after turning over. When the coolant temp gauge starts to rise again, it holds throttle and I can ride again.

Another thing I noticed, I was trying to keep it running, so I had the choke on, and the engine was somewhat warm, RPMs jumped to 6k and hold, when I applied some throttle the RPMs would fall until I let off the throttle.

Am I looking at bad gas, clogged jets, non sync carbs, vacuum issue?? Best place to start?

krolinked · May 24th, 2013, 05:05 PM

I think it might be too lean. Too much air for the amount of gas, thats why it works better warm...

Motofool · May 24th, 2013, 08:02 PM

Welcome to our site, Steven !!!

An old model with so few miles must have many fuel and carburetor problems.

The temperature that your gauge shows is irrelevant, unless it goes above the red mark.
When the bike moves fast, the gauge will show cool and when at idle, it will show hot; it is just normal.

The easiest to check first is the plumbing.
These bikes are prone to clogged ventilation of the tank and to inner and in-line filters (due to junk) and petcock (due to insufficient vacuum) restricting flow.

There is tiny mesh filter inside the end of the hose that feeds the carbs.

If you get consistent flow at the end of the feeding hose (about 2 cc per second), the next step is to clean the carburetors.

scubaru · May 24th, 2013, 08:51 PM

Quote:

Originally Posted by Motofool

Welcome to our site, Steven !!!

An old model with so few miles must have many fuel and carburetor problems.

The temperature that your gauge shows is irrelevant, unless it goes above the red mark.
When the bike moves fast, the gauge will show cool and when at idle, it will show hot; it is just normal.

The easiest to check first is the plumbing.
These bikes are prone to clogged ventilation of the tank and to inner and in-line filters (due to junk) and petcock (due to insufficient vacuum) restricting flow.

There is tiny mesh filter inside the end of the hose that feeds the carbs.

If you get consistent flow at the end of the feeding hose (about 2 cc per second), the next step is to clean the carburetors.

Awesome! I'll take a look tomorrow. So far I plan to drain the bowls and tank of the old gas, check spark plugs and air filter then try again.

If not ill look at doing a carb cleaner soak so as not to tear them apart if I can avoid it.

Asspire · May 24th, 2013, 09:35 PM

also, you'll wanna go ahead and replace ALL rubber hoses. A bike with that age and mileage has been sitting for a long time, and when they sit, they rot. When i bought my bike it only had 600 miles, but sat for 4 years, even the rubber on the fairing nuts were dry rot and cracked. Replace all vacuum, brake, coolant, gas hoses, hell, even the o-rings on float bowls needed to be replaced. Last thing you want is a leak, of any of those fluids (replace all fluids too). And tear apart your carbs and clean them, better to the the job once right, rather than half way a couple times.

after that, ride the piss outta it.

scubaru · May 25th, 2013, 08:50 PM

Quote:

Originally Posted by Asspire

also, you'll wanna go ahead and replace ALL rubber hoses. A bike with that age and mileage has been sitting for a long time, and when they sit, they rot. When i bought my bike it only had 600 miles, but sat for 4 years, even the rubber on the fairing nuts were dry rot and cracked. Replace all vacuum, brake, coolant, gas hoses, hell, even the o-rings on float bowls needed to be replaced. Last thing you want is a leak, of any of those fluids (replace all fluids too). And tear apart your carbs and clean them, better to the the job once right, rather than half way a couple times.

after that, ride the piss outta it.

Opened my carbs expecting the worst...

Nothing! The rest of the carbs look amazing, no build up,neverything moves smooth. Safe to say not the carbs?

All the rubber lines look amazing inside and out, no cracks or rot. I am truly stumped

scubaru · May 26th, 2013, 06:06 PM

So I drained the bowls and tank, got some new gas in it and works PERFECT!!

This was the old gasoline...

Motofool · May 26th, 2013, 06:17 PM

Quote:

Originally Posted by scubaru

So I drained the bowls and tank, got some new gas in it and works PERFECT!!

Glad that you solved the mystery !!!

scubaru · May 26th, 2013, 06:26 PM

Quote:

Originally Posted by Motofool

Glad that you solved the mystery !!!

Thanks! Happy it was so simple and I got to see how everything fits on my bike

May 24th, 2013, 04:52 PM	#1
scubaru ninjette.org member Name: Steve Location: Hanover, PA Join Date: May 2013 Motorcycle(s): 2005 Ninja 250 Posts: 35	Irregular idle and stalling at speed So I recently purchased a 2005 Ninja 250. Bike is completely stock with a mere 798 miles on it. The issues are all closely related and I'm sure its probably one fix. Conditions: Lebanon, Pennsylvania (elevation 480') 50* with 46% Humidity Windy with overcast and storms this morning So the first issue was idle, I would start it up with the choke on and the RPMs would sit at 0, but was still running, if I let the clutch lever out (in Neutral) it would stall it out. Played with the idle controller and got it to stay running. Once I got it up to operating temperature I played with the idle control again to bring the RPMs to 1500. Noticed at this point after I let off the throttle the RPMs hold high for awhile then come down. So I went out for a drive, everything was fine, slight hesitation in the throttle but nothing I would find problematic. Going down a straightaway I hit tops 40 mph, watch my coolant temp drop to within an 1/8" of the bottom of the temp span. Notice my throttle disappearing and suddenly I lose power. Coast to the side of the road and keep trying to get it to stay running after turning over. When the coolant temp gauge starts to rise again, it holds throttle and I can ride again. Another thing I noticed, I was trying to keep it running, so I had the choke on, and the engine was somewhat warm, RPMs jumped to 6k and hold, when I applied some throttle the RPMs would fall until I let off the throttle. Am I looking at bad gas, clogged jets, non sync carbs, vacuum issue?? Best place to start?

May 24th, 2013, 05:05 PM	#2
krolinked Nerd Name: Chris Location: Tujunga Join Date: Mar 2012 Motorcycle(s): Ducati Hyperstrada Posts: 672	I think it might be too lean. Too much air for the amount of gas, thats why it works better warm... __________________________________________________ It doesn't LOOK that steep. But you can go first...

May 24th, 2013, 08:02 PM	#3
Motofool Daily Ninjette rider Name: Hernan Location: Florida Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot. MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16	Welcome to our site, Steven !!! An old model with so few miles must have many fuel and carburetor problems. The temperature that your gauge shows is irrelevant, unless it goes above the red mark. When the bike moves fast, the gauge will show cool and when at idle, it will show hot; it is just normal. The easiest to check first is the plumbing. These bikes are prone to clogged ventilation of the tank and to inner and in-line filters (due to junk) and petcock (due to insufficient vacuum) restricting flow. There is tiny mesh filter inside the end of the hose that feeds the carbs. If you get consistent flow at the end of the feeding hose (about 2 cc per second), the next step is to clean the carburetors. __________________________________________________ *Motofool* *.................................Never ride faster than your guardian angel can fly* "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí

May 24th, 2013, 09:35 PM	#5
Asspire Fix It Till Ya Break It Name: Asspyre Location: T.Dot Join Date: Oct 2011 Motorcycle(s): 08 250RRrrrr Posts: 623	also, you'll wanna go ahead and replace ALL rubber hoses. A bike with that age and mileage has been sitting for a long time, and when they sit, they rot. When i bought my bike it only had 600 miles, but sat for 4 years, even the rubber on the fairing nuts were dry rot and cracked. Replace all vacuum, brake, coolant, gas hoses, hell, even the o-rings on float bowls needed to be replaced. Last thing you want is a leak, of any of those fluids (replace all fluids too). And tear apart your carbs and clean them, better to the the job once right, rather than half way a couple times. after that, ride the piss outta it.
	1 out of 1 members found this post helpful.

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May 26th, 2013, 06:06 PM	#7
scubaru ninjette.org member Name: Steve Location: Hanover, PA Join Date: May 2013 Motorcycle(s): 2005 Ninja 250 Posts: 35	So I drained the bowls and tank, got some new gas in it and works PERFECT!! This was the old gasoline...