Really Weird carb Issue need more trouble shooting ideas

Virustech · September 23rd, 2012, 12:55 PM

Alright just gonna cut right to the chase hereon my 95 Ninja 250ex My carbs are losing fuel out of the body and were the air intake is for the pilots IE the two little holes below the intake on the rear of the carb. Im at a loss to what could be causing this problem. As far as what I have done to them so far is as follows.

Cleaned them with carb cleaner really well
Cleaned pilots and mains and all the little nooks that go to them
Set the floats to factory specs of 17mm (it is not leaking from the bowl overflow)
Pulled the top diphram off checked for holes in it and checked for bent needles there in great shape.

So im at a loss here for what else to check. Not sure and have never seen this on any of the carbs I have ever worked on. Very knowledgable about carbs so if you have a list of things to check other than what I have posted just post a list im at a loss here and this is my last resort before I just buy a new set!

Thanks for the help in advance hope we can figure it out cuz im ready to $&$---&@&$ lol

OldTimer · September 23rd, 2012, 03:26 PM

The only thing you didn't mention was cleaning out the float needles and their seats. If there was a little debris in there it could hold the float needle open and not let it shut even though you set the float to 17mm. Not much else I can think of that will cause your bowls to overflow. Also your petcock should prevent the bike from leaking fuel since they are vacuum activated. I would check there for leaks too! Sorry, that's all I can think of...

Motofool · September 23rd, 2012, 03:33 PM

I agree with Nick.

Besides, are the bowls properly ventilated to the atmosphere?
If not, some air pressure may be developing inside, pushing fuel in the direction you have explained rather the overflow tube.

Virustech · September 23rd, 2012, 04:51 PM

Yea cleaned the float seats all the vents are gtg not sure might just need to pickup a new pair on ebay and see whats up. Almost seems like a vacuum problem its got me stumped big time

Virustech · September 23rd, 2012, 05:14 PM

So I got it to start and run now its dumping fuel out of the overflow line. Pretty sure thats the float seat causing it. I have adjusted the float a few times and its in spec right now and its still dumping out the over flow. Pretty sure thats a seat issue.

But seems to be a vacuum issue as well. I cant get it to start if the vacuum hose is hooked to the petcock but if I remove it it will start then I pop it back on it will run. It revs from 3000 to 5000 up and down up and down then it will just die. It almost seems as though A its not getting enough fuel to fill the bowl or B its emptying the bowl and filling it and emptying it again. kinda got tired of messing with it tonight tom afternoon Ill shoot some HD video of the issue and post it up and link it on here and see what ya think. I would hate like hell to buy a rebuild kit for it just to have it be something else thats causing the issue. So im really trying to get a good diagnosis before I spend alot of money.

This bike I got a week ago for $600 not running so im not that much into it right now just so far put a CDI and Stator in it.

Motofool · September 23rd, 2012, 05:40 PM

Have you checked the ventilation of the tank?
Try crack opening the cap.

In order to eliminate the vacuum and petcock issue, you could feed the carbs by gravity only from a second vented tank and hose and see how the floats work.

OldTimer · September 23rd, 2012, 05:46 PM

I recently had a similar problem with an Amal Concentric carburetor on a 1968 BSA Thunderbolt. Since they are hard to find parts for, I took some valve grinding compound and put some on the seat and gently rotated the float needle in there. It was like what you do when you're seating a valve into a valve seat. Anyway I cleaned out all the valve grinding compound real good and then assembled the carb and it quit leaking. You might want to give that a try but you definitely do not want valve grinding compound in your engine. So make sure you clean it real good. It doesn't take much to seat the needle valve. Just a tip from something I did to solve a similar problem.

BTW, how much did the CDI cost, I think mine is not advancing so I want to buy a new one.

Virustech · September 23rd, 2012, 07:15 PM

i got the CDI for about $85 they had some cheaper ones but the numbers did not match so I did not want to chance it

Virustech · September 23rd, 2012, 07:17 PM

Quote:

Originally Posted by Motofool

Have you checked the ventilation of the tank?
Try crack opening the cap.

In order to eliminate the vacuum and petcock issue, you could feed the carbs by gravity only from a second vented tank and hose and see how the floats work.

I checked the petcock for dirt cleaned it the diaphram looked ok checked all the vacuum lines ect. Tried opening the cap on the tank same issues.

OldTimer · September 24th, 2012, 01:58 PM

did you try to lap the needle valve into the seat? Did you get your CDI on ebay?

Virustech · September 24th, 2012, 06:34 PM

Well I figured it out guys it was the float needles the little holder wires seemed to be stretched out really bad so I gave them a little help bent them down and all is well now. Starts right up no problems and runs like a champ.

The vacuum issues worked themselfs out its still having some idle issues but im gonna throw some seafoam in a full tank of fuel and get her out and that should help alot.

Thanks for all your info guys..

Virustech · September 24th, 2012, 06:35 PM

Quote:

Originally Posted by OldTimer

did you try to lap the needle valve into the seat? Did you get your CDI on ebay?

yes I got my CDI on ebay

September 23rd, 2012, 12:55 PM	#1
Virustech ninjette.org newbie Name: Josh Location: Batavia Join Date: Sep 2012 Motorcycle(s): 250 ninja Posts: 7	Really Weird carb Issue need more trouble shooting ideas Alright just gonna cut right to the chase hereon my 95 Ninja 250ex My carbs are losing fuel out of the body and were the air intake is for the pilots IE the two little holes below the intake on the rear of the carb. Im at a loss to what could be causing this problem. As far as what I have done to them so far is as follows. Cleaned them with carb cleaner really well Cleaned pilots and mains and all the little nooks that go to them Set the floats to factory specs of 17mm (it is not leaking from the bowl overflow) Pulled the top diphram off checked for holes in it and checked for bent needles there in great shape. So im at a loss here for what else to check. Not sure and have never seen this on any of the carbs I have ever worked on. Very knowledgable about carbs so if you have a list of things to check other than what I have posted just post a list im at a loss here and this is my last resort before I just buy a new set! Thanks for the help in advance hope we can figure it out cuz im ready to $&$---&@&$ lol

September 23rd, 2012, 03:33 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	I agree with Nick. Besides, are the bowls properly ventilated to the atmosphere? If not, some air pressure may be developing inside, pushing fuel in the direction you have explained rather the overflow tube. __________________________________________________ *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

September 23rd, 2012, 05:40 PM	#6
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	Have you checked the ventilation of the tank? Try crack opening the cap. In order to eliminate the vacuum and petcock issue, you could feed the carbs by gravity only from a second vented tank and hose and see how the floats work. __________________________________________________ *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

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September 23rd, 2012, 03:26 PM	#2
OldTimer ninjette.org member Name: Nick Location: Florida Join Date: Sep 2012 Motorcycle(s): Hayabusa, Vespa 200GT, Harley Electraglide, Ninja 250 Posts: 20	The only thing you didn't mention was cleaning out the float needles and their seats. If there was a little debris in there it could hold the float needle open and not let it shut even though you set the float to 17mm. Not much else I can think of that will cause your bowls to overflow. Also your petcock should prevent the bike from leaking fuel since they are vacuum activated. I would check there for leaks too! Sorry, that's all I can think of...

September 23rd, 2012, 04:51 PM	#4
Virustech ninjette.org newbie Name: Josh Location: Batavia Join Date: Sep 2012 Motorcycle(s): 250 ninja Posts: 7	Yea cleaned the float seats all the vents are gtg not sure might just need to pickup a new pair on ebay and see whats up. Almost seems like a vacuum problem its got me stumped big time

September 23rd, 2012, 05:14 PM	#5
Virustech ninjette.org newbie Name: Josh Location: Batavia Join Date: Sep 2012 Motorcycle(s): 250 ninja Posts: 7	So I got it to start and run now its dumping fuel out of the overflow line. Pretty sure thats the float seat causing it. I have adjusted the float a few times and its in spec right now and its still dumping out the over flow. Pretty sure thats a seat issue. But seems to be a vacuum issue as well. I cant get it to start if the vacuum hose is hooked to the petcock but if I remove it it will start then I pop it back on it will run. It revs from 3000 to 5000 up and down up and down then it will just die. It almost seems as though A its not getting enough fuel to fill the bowl or B its emptying the bowl and filling it and emptying it again. kinda got tired of messing with it tonight tom afternoon Ill shoot some HD video of the issue and post it up and link it on here and see what ya think. I would hate like hell to buy a rebuild kit for it just to have it be something else thats causing the issue. So im really trying to get a good diagnosis before I spend alot of money. This bike I got a week ago for $600 not running so im not that much into it right now just so far put a CDI and Stator in it.

September 23rd, 2012, 05:46 PM	#7
OldTimer ninjette.org member Name: Nick Location: Florida Join Date: Sep 2012 Motorcycle(s): Hayabusa, Vespa 200GT, Harley Electraglide, Ninja 250 Posts: 20	I recently had a similar problem with an Amal Concentric carburetor on a 1968 BSA Thunderbolt. Since they are hard to find parts for, I took some valve grinding compound and put some on the seat and gently rotated the float needle in there. It was like what you do when you're seating a valve into a valve seat. Anyway I cleaned out all the valve grinding compound real good and then assembled the carb and it quit leaking. You might want to give that a try but you definitely do not want valve grinding compound in your engine. So make sure you clean it real good. It doesn't take much to seat the needle valve. Just a tip from something I did to solve a similar problem. BTW, how much did the CDI cost, I think mine is not advancing so I want to buy a new one.

September 23rd, 2012, 07:15 PM	#8
Virustech ninjette.org newbie Name: Josh Location: Batavia Join Date: Sep 2012 Motorcycle(s): 250 ninja Posts: 7	i got the CDI for about $85 they had some cheaper ones but the numbers did not match so I did not want to chance it

September 24th, 2012, 01:58 PM	#10
OldTimer ninjette.org member Name: Nick Location: Florida Join Date: Sep 2012 Motorcycle(s): Hayabusa, Vespa 200GT, Harley Electraglide, Ninja 250 Posts: 20	did you try to lap the needle valve into the seat? Did you get your CDI on ebay?

September 24th, 2012, 06:34 PM	#11
Virustech ninjette.org newbie Name: Josh Location: Batavia Join Date: Sep 2012 Motorcycle(s): 250 ninja Posts: 7	Well I figured it out guys it was the float needles the little holder wires seemed to be stretched out really bad so I gave them a little help bent them down and all is well now. Starts right up no problems and runs like a champ. The vacuum issues worked themselfs out its still having some idle issues but im gonna throw some seafoam in a full tank of fuel and get her out and that should help alot. Thanks for all your info guys..