Carbs Overflow

Oren09 · February 1st, 2016, 08:48 PM

Hello all,

I am having a bit of a carb issue. Here's some backstory:

I bought a 1994 EX250 for a cheap project just to see if I could get it to run.
Started with no spark on one coil and that was resolved with a new CDI. Then I was only getting combustion on one cylinder, but on both with some carb cleaner sprayed into the airbox.
I took the carbs apart for a rebuild and found molasses in the bowl of the cylinder that wasn't firing. No surprise.

Today I reassembled the carbs and installed them on the bike. I love doing carbs on this machine vs an 89 Ninja 750 I used to have.
I'm using an auxiliary tank hanging from the ceiling to supply fuel; not the bike's gas tank. The bike fired up and ran, but wouldn't idle. May just need adjustment. I didn't get enough time to mess with that because gas started flowing out of the carbs. I suspected float valves and pulled the carbs, opened them up, and adjusted the floats lower. After putting the carbs back on, they still overflow. A strong and steady stream from the overflow tube. I thought maybe my tank was putting out too much pressure due to gravity but the carbs still leak even with the tank at their level.

I've now had the bowls off checking the floats, valves, seats, etc several times. I am out of ideas. The valves are new from the rebuild kit and look just like the old ones.

csmith12 · February 1st, 2016, 09:11 PM

Welcome Austin!

Hmmm, seems you have checked all the baseline stuff already. Maybe someone else will have another idea.

Motofool · February 1st, 2016, 09:43 PM

Quote:

Originally Posted by Oren09

.......... The valves are new from the rebuild kit and look just like the old ones.

Welcome, Austin !!!

If the float valves are new (soft rubber tip), the seats are still dirty.

The height of the floats must be kept at factory specs: 17 mm measured from the edge at close to vertical position.

If oil gets contaminated with the overflowing gas via the intake valves, you must replace the oil to prevent damage to the main bearings.

Sarge1992 · February 1st, 2016, 09:55 PM

Make sure the rubber tip isn't stuck on the seat, when I ripped mine apart the rubber tip fell off the old float and was sticking to the seat.

RacinNinja · February 1st, 2016, 09:59 PM

To narrow down which one is leaking, do the following.

Remove carbs
Remove bowls
Hold carbs upside down
Attach CLEAN hose to fuel pipe and blow into it
You should not have air coming from the needle valves. If you do...you'll know which one is leaking.
Seats are probably dirty as previously mentioned.

HoneyBadgerRy · February 3rd, 2016, 10:31 AM

I had a problem where with brand new float seals, properly adjusted floats, and new boat seals it still overflowed, I shaked the bike around a little (carbs full of gas) and it stopped leaking. I think that the floats just bined up.

Oren09 · February 3rd, 2016, 10:31 AM

Thanks for the replies guys.

I haven't had time to further troubleshoot but hopefully today or tomorrow.

I forgot to mention that I also adjusted the valves while waiting for the carb rebuild kits. All of the valve clearances were way tight with the engine at 25K miles.

Oren09 · February 8th, 2016, 09:08 PM

I was finally able to mess with the carbs again.

I checked the float valves by blowing through with the carbs upside down and sure enough they were leaking.

I cleaned the seats, tested again, and no leaks. I guess I just didn't get the seats clean enough the first time.

The bike runs pretty good but while setting the idle mixture screw (bike was hanging revs after giving it gas) the starter decided to die.

I disassembled the starter and the magnets came out stuck to the armature along with massive amounts of carbon. The body was rusty inside as well.
I have a new used starter en route.

RacinNinja · February 8th, 2016, 09:20 PM

Quote:

Originally Posted by Oren09

I was finally able to mess with the carbs again.

I checked the float valves by blowing through with the carbs upside down and sure enough they were leaking.

I cleaned the seats, tested again, and no leaks. I guess I just didn't get the seats clean enough the first time.

The bike runs pretty good but while setting the idle mixture screw (bike was hanging revs after giving it gas) the starter decided to die.

I disassembled the starter and the magnets came out stuck to the armature along with massive amounts of carbon. The body was rusty inside as well.
I have a new used starter en route.

Good job!!

Motofool · February 8th, 2016, 09:33 PM

Quote:

Originally Posted by Oren09

.........

I cleaned the seats, tested again, and no leaks........

Did you adjust the height of the floats?

February 1st, 2016, 08:48 PM	#1
Oren09 ninjette.org newbie Name: Austin Location: DFW, TX Join Date: Jan 2016 Motorcycle(s): 1994 EX250, 2012 FZ1 Posts: 3	Carbs Overflow Hello all, I am having a bit of a carb issue. Here's some backstory: I bought a 1994 EX250 for a cheap project just to see if I could get it to run. Started with no spark on one coil and that was resolved with a new CDI. Then I was only getting combustion on one cylinder, but on both with some carb cleaner sprayed into the airbox. I took the carbs apart for a rebuild and found molasses in the bowl of the cylinder that wasn't firing. No surprise. Today I reassembled the carbs and installed them on the bike. I love doing carbs on this machine vs an 89 Ninja 750 I used to have. I'm using an auxiliary tank hanging from the ceiling to supply fuel; not the bike's gas tank. The bike fired up and ran, but wouldn't idle. May just need adjustment. I didn't get enough time to mess with that because gas started flowing out of the carbs. I suspected float valves and pulled the carbs, opened them up, and adjusted the floats lower. After putting the carbs back on, they still overflow. A strong and steady stream from the overflow tube. I thought maybe my tank was putting out too much pressure due to gravity but the carbs still leak even with the tank at their level. I've now had the bowls off checking the floats, valves, seats, etc several times. I am out of ideas. The valves are new from the rebuild kit and look just like the old ones.

February 1st, 2016, 09:11 PM	#2
csmith12 The Corner Whisperer Name: Chris (aka Reactor) Location: Northern KY Join Date: May 2011 Motorcycle(s): 2010 250 (track), 1992 250, 2006 R6 (street/track), 2008 R6 (track) Posts: Too much. MOTY 2015, MOTM - Nov '12, Nov '13	Welcome Austin! Hmmm, seems you have checked all the baseline stuff already. Maybe someone else will have another idea. __________________________________________________ Goal: Shake A Million Hands \| Look through the corners \| Track Day Prep \| Closest track? \| The Mid-Ohio School

February 1st, 2016, 09:55 PM	#4
Sarge1992 ninjette.org member Name: Ryan Location: Tampa, FL Join Date: Dec 2015 Motorcycle(s): 2014 Kawasaki Ninja 650R Posts: 67	Make sure the rubber tip isn't stuck on the seat, when I ripped mine apart the rubber tip fell off the old float and was sticking to the seat.
	1 out of 1 members found this post helpful.

February 1st, 2016, 09:59 PM	#5
RacinNinja Vintage Screwball Name: B Location: Washington Join Date: Feb 2016 Motorcycle(s): 2011 Ninja 250, 2008 Ninja 250, 2019 KTM 1290SDR, 2017 FZ10 Posts: A lot. MOTM - Mar '16	To narrow down which one is leaking, do the following. Remove carbs Remove bowls Hold carbs upside down Attach CLEAN hose to fuel pipe and blow into it You should not have air coming from the needle valves. If you do...you'll know which one is leaking. Seats are probably dirty as previously mentioned.
	1 out of 1 members found this post helpful.

February 3rd, 2016, 10:31 AM	#6
HoneyBadgerRy ninjette.org certified postwhore Name: Ryan Location: Beaufort SC Join Date: Aug 2015 Motorcycle(s): 05 Ninja 250, 04 KTM 625 SMC, 01 Xc250 Posts: A lot. Blog Entries: 3	I had a problem where with brand new float seals, properly adjusted floats, and new boat seals it still overflowed, I shaked the bike around a little (carbs full of gas) and it stopped leaking. I think that the floats just bined up. __________________________________________________ Because Unregistered sucks at riding.

February 8th, 2016, 09:08 PM	#8
Oren09 ninjette.org newbie Name: Austin Location: DFW, TX Join Date: Jan 2016 Motorcycle(s): 1994 EX250, 2012 FZ1 Posts: 3	I was finally able to mess with the carbs again. I checked the float valves by blowing through with the carbs upside down and sure enough they were leaking. I cleaned the seats, tested again, and no leaks. I guess I just didn't get the seats clean enough the first time. The bike runs pretty good but while setting the idle mixture screw (bike was hanging revs after giving it gas) the starter decided to die. I disassembled the starter and the magnets came out stuck to the armature along with massive amounts of carbon. The body was rusty inside as well. I have a new used starter en route.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Radiator Overflow Tank Size	VaFish	1986 - 2007 Ninja 250R Tech Talk	8	December 1st, 2015 10:13 AM
Fuel Overflow Problem	CWLESQ	1986 - 2007 Ninja 250R Tech Talk	11	September 26th, 2013 05:39 AM
Coolant overflow and overheating Help Please.	nefiwashere	1986 - 2007 Ninja 250R Tech Talk	8	August 31st, 2012 06:24 PM
Carb overflow. What could cause this to happen?	Monkeytofu	1986 - 2007 Ninja 250R Tech Talk	25	August 1st, 2012 11:41 AM
oil leak from an overflow hose?	pinkandblack	2008 - 2012 Ninja 250R Tech Talk	30	June 17th, 2011 10:34 PM