Carb overflow. What could cause this to happen?

[Monkeytofu]

So I've been working on my bike for the past 2 weeks changing the cooling fluid, rebuilding the petcock, painting my exhaust pipes, replacing my long gone air filter, and adjusting the valves twice. Last week when I went and adjusted the valves once more I put the bike back together again. After riding it a bit with the petcock set on the "OFF" position, I noticed the drop in RPM and stuttering of the bike that happens when it's in that so I switched it back to on. I drove around for about half a minute when my bike started to lose power and began to dump gas out of the overflow tube.

So I've been able to run my ninja as if it were new when it's set into off but as soon as I put it on the "on" setting it just dumps gas out. Any ideas on what it could be? Something is causing too much fuel to enter my carbs but I have no idea what it could be.

This only happened after I adjusted the valves, but I don't think that's the cause of it.

[Motofool]

Noor,

Each carb has a float and a valve inside the bowl.
The function of this float-valve is to regulate the level of fuel inside that bowl (which is important for the amount of fuel that the engine sucks via main jet).

In your case, one of both of those mechanisms is not working properly and is allowing the fuel level to raise up to overflow the bowls and mess up the mix (way too rich).

Sometimes the plastic float leaks in and sinks.
The most common malfunction is a leaky valve (the float pushes up but the valve doesn't close completely).
Valves can leak due to wear, stock debris and dislocation from the proper position.

Try fixing the last one tapering the bowl carefully but vigorously with the handle of a screwdriver.

A very bad consequence is fuel leaking down into the crankcase and contaminating the oil (oil level raises up noticeably).

[GeorgeRYoung]

If the float bowl tapping doesn't work, this might.

There may be a bit of junk stuck between the float needle and its seat.

With the petcock set to off, open the float drain bolt on the bottom, of course with a suitable length of tubing and container to catch the float bowl worth of gas. Then tighten the drain bolt.

If you're lucky, the gunk will get washed out by the fuel inrush when you turn the gas to on and run the engine.

[Monkeytofu]

Originally Posted by Motofool

Noor,

Each carb has a float and a valve inside the bowl.
The function of this float-valve is to regulate the level of fuel inside that bowl (which is important for the amount of fuel that the engine sucks via main jet).

In your case, one of both of those mechanisms is not working properly and is allowing the fuel level to raise up to overflow the bowls and mess up the mix (way too rich).

Sometimes the plastic float leaks in and sinks.
The most common malfunction is a leaky valve (the float pushes up but the valve doesn't close completely).
Valves can leak due to wear, stock debris and dislocation from the proper position.

Try fixing the last one tapering the bowl carefully but vigorously with the handle of a screwdriver.

A very bad consequence is fuel leaking down into the crankcase and contaminating the oil (oil level raises up noticeably).

Me and a friend tried tapping the carbs (not sure if he tapped the bowls as you suggested) but I'll try it again and see what happens.

I've just looked at the oil and it is extremely high. Should I just drain out a bit of it?

Originally Posted by GeorgeRYoung

If the float bowl tapping doesn't work, this might.

There may be a bit of junk stuck between the float needle and its seat.

With the petcock set to off, open the float drain bolt on the bottom, of course with a suitable length of tubing and container to catch the float bowl worth of gas. Then tighten the drain bolt.

If you're lucky, the gunk will get washed out by the fuel inrush when you turn the gas to on and run the engine.

So just empty the bowls of while in off and run them again? I'll try this if Motofool's suggestion doesn't work.

Thanks for the help guys

EDIT: Gave it a couple of taps, still seems to overflow :/ I'll be trying to drain them. I'm assuming my next step would be to take them off and clean them right?

EDIT2: Drained both of them and some black specs (of dirt I think) was in the gas that came from the left one. The overflow tube wasn't gushing like before, but it still was overflowing. Going to add a inline filter as soon as I get this fixed and I can actually go out and buy one.

[Motofool]

Sorry for the late reply.

If the oil level was correct before this problem, then the oil has been contaminated with much gasoline and should be replaced.

Gasoline interferes with lubrication; hence, it could damage high loaded parts of the engine.

I wouldn't replace the oil filter, just the oil.

If the oil level was high before, you may want to take the risk.
Contaminated oil has a strong gasoline smell (it normally has some).

Before proceeding to surgery, you could try flushing the valve's seats forcing fuel through it with a hand pump or just by siphoning, keeping the drain bolts open.

[Monkeytofu]

Originally Posted by Motofool

Sorry for the late reply.

If the oil level was correct before this problem, then the oil has been contaminated with much gasoline and should be replaced.

Gasoline interferes with lubrication; hence, it could damage high loaded parts of the engine.

I wouldn't replace the oil filter, just the oil.

If the oil level was high before, you may want to take the risk.
Contaminated oil has a strong gasoline smell (it normally has some).

Before proceeding to surgery, you could try flushing the valve's seats forcing fuel through it with a hand pump or just by siphoning, keeping the drain bolts open.

Seems like I'll be replacing both the oil and taking the carbs out . I tried flushing the carbs once more as suggested above and no luck. I'll try to find a pump I can use to try and use your method of flushing.

[Monkeytofu]

I removed the carbs and found some strange things. First, one of the screws holding it together was missing. I had never touched it, so it was either the previous owner had removed them and forgot to put that one in or the mechanic who worked on my bike forgot to put it back in when I first bought this bike.

Also the rubber sealers were regular rubber o rings that were held into the shape of the channel they were in. Is this normal for older years? All the rebuild kits and the schematic @Motofool posted all show it to be preformed into the shape.

Some dirt came out of one of the needles and I think that may be it. Me and my friend will be putting the carbs back on and testing them tomorrow. Any tips on how to test them without have to rebuild the entire damn bike?

[DaBlue1]

Originally Posted by Monkeytofu

.... After riding it a bit with the petcock set on the "OFF" position, I noticed the drop in RPM and stuttering of the bike that happens when it's in that so I switched it back to on. I drove around for about half a minute when my bike started to lose power and began to dump gas out of the overflow tube.

.... when it's set into off but as soon as I put it on the "on" setting it just dumps gas out. Any ideas on what it could be? Something is causing too much fuel to enter my carbs but I have no idea what it could be.

This only happened after I adjusted the valves, but I don't think that's the cause of it.

Turn the petcock off. Remove the gas line from the carb, then turn the petock to "ON", if gas flows without the assistance of a vacuum, then the petcock may be the problem.

[Monkeytofu]

Originally Posted by DaBlue1

Turn the petcock off. Remove the gas line from the carb, then turn the petock to "ON", if gas flows without the assistance of a vacuum, then the petcock may be the problem.

I don't know what else would be broken in the petcock considered I rebuilt it with brand new OEM parts.

[Motofool]

Originally Posted by Monkeytofu

..........Also the rubber sealers were regular rubber o rings that were held into the shape of the channel they were in. Is this normal for older years? .........Me and my friend will be putting the carbs back on and testing them tomorrow. Any tips on how to test them without have to rebuild the entire damn bike?

Those are not the proper sealers.

The seals are conical shaped neoprene inserted in brass, like the picture shows.

Ronayers has the part, which number is 16030-1007 and cost ~$26 each.

Improvised O-rings aren't substitute for those parts, IMHO, especially is they disintegrate in gasoline + ethanol.

The way to test the valves is connecting a hose long enough to mimic the height level of a full tank above the carbs and fill it up with gas: the valves shouldn't allow any gas into the carbs once the bowls reach the specified level.

This is a good opportunity to verify the level that the fuel reaches inside the bowls (when valves are closing properly).

[Monkeytofu]

Originally Posted by Motofool

Those are not the proper sealers.

The seals are conical shaped neoprene inserted in brass, like the picture shows.

Ronayers has the part, which number is 16030-1007 and cost ~$26 each.

Improvised O-rings aren't substitute for those parts, IMHO, especially is they disintegrate in gasoline + ethanol.

The way to test the valves is connecting a hose long enough to mimic the height level of a full tank above the carbs and fill it up with gas: the valves shouldn't allow any gas into the carbs once the bowls reach the specified level.

This is a good opportunity to verify the level that the fuel reaches inside the bowls (when valves are closing properly).

Sorry to confuse you like that, I meant the sealer between the the two pieces of the carb(90255). the oddly shaped rubber tubing in the schematic you posted earlier. If there was a way to "glue" it into the ridge it would be so much easier to put back together...

I'll try that way of filling them tomorrow; hopefully I have cleaned them out sufficiently.

[dirty nasty]

Your floats are stuck/leaking. What caused it is age (but I doubt that as I've rode on motorcycles with 30+ year old needle valves) or crap getting sucked through your carbs. Most likely, it was crap getting sucked through your carbs. You need to install an in-line fuel filter and keep it changed/fresh/clean before running the bike again. This will severely lessen the chances of this happening again. Believe me, it's worth it when you rebuild your carbs and the damn things start leaking out of the overflow because a small flake of rust in the tank broke loose and held the float stuck open, requiring you take them off and take them apart, AGAIN.

[Motofool]

Sorry, Noor, I misread your description.

That seal will not prevent the gasoline to leak out but it will prevent dust and water from the road to get inside the bowls.

I imagine the nightmare of trying conforming a circular O-ring into that groove.

This may help:
http://www.permatex.com/products/Aut...ge_sealant.htm

Just in case you don't have the manual, here is how to measure the proper fuel level.

Do not lower the tube down and up again, once the level is set, or you will get a false measurement.

[Monkeytofu]

So I've fixed the leak! I've also installed a fuel line filter and changed the oil. On pouring out the oil I noticed that the oil had a massive amount of gas in it, and it's good I went ahead and changed it.

However... after running my bike for a bit around the neighborhood my bike started to lose power. It soon after started to dip below 1000 RPM and stall out anytime I would release the clutch. The RPMs seemed to stall around 3-5 RPM. My bike stays running in idle and I have not seen a single leak so I'm attributing this to something me and my friend did wrong while assembling it.

Any ideas?

[DaBlue1]

Originally Posted by Monkeytofu

...So I've fixed the leak! I've also installed a fuel line filter and changed the oil. .....after running my bike for a bit around the neighborhood my bike started to lose power.

How did you fix it?
Did you try removing the fuel filter to see if the problem with power lose continued?

[Monkeytofu]

Originally Posted by DaBlue1

How did you fix it?
Did you try removing the fuel filter to see if the problem with power lose continued?

I just gave the carbs a thorough cleaning with carb cleaner. I don't think it has anything to do with lack of fuel because my engine will rev relatively fine while in neutral (but with a rough spot) but will just lose all power as soon as I let go of the clutch regardless of where the RPM is at. I can squeeze down on the clutch to keep the bike on or put it back into neutral to keep it on.

[DaBlue1]

Originally Posted by Monkeytofu

I just gave the carbs a thorough cleaning with carb cleaner.

Hopefully you did it with the diaphragms out.

[Monkeytofu]

Originally Posted by DaBlue1

Hopefully you did it with the diaphragms out.

Err... I didn't. Could that be the issue? I didn't flood the thing with carb cleaner though. Took parts out and cleaned them and cleaned the metal parts with carb cleaner and a tooth brush.

Edit: how would that damage it though? I didn't use anything other than carb cleaner which I assume is safe for any part within the carb.

[alex.s]

revving the engine is almost no strain. if it has no power, any strain will kill it. maybe running way lean? did you do a plug check?

the fact that it ran fine then got bad seems to me like your tank or fuel filter is dirty and just reclogging your carbs

[Monkeytofu]

Originally Posted by alex.s

revving the engine is almost no strain. if it has no power, any strain will kill it. maybe running way lean? did you do a plug check?

the fact that it ran fine then got bad seems to me like your tank or fuel filter is dirty and just reclogging your carbs

I just added this fuel filter two days ago. to my eyes it looks absolutely clean. While my gas has been sitting outside for a week or two, it still looks very clean. haven't seen any residue from the gas I removed from my tank without the filter.

Should I go ahead and try some new gas?

Edit1: will be checking plugs in a few.

[alex.s]

i would dump the gas, reclean the carbs, and start with fresh gas. dont worry about the plug check until after you know you have a good clean system.

[DaBlue1]

Originally Posted by Monkeytofu

Err... I didn't. Could that be the issue? I didn't flood the thing with carb cleaner though. Took parts out and cleaned them and cleaned the metal parts with carb cleaner and a tooth brush.

Edit: how would that damage it though? I didn't use anything other than carb cleaner which I assume is safe for any part within the carb.

If you sprayed carb cleaner into the ports on the back of carbs, there may be a very small possibility of damage.

How is the fuel level in the new filter when the bike is running? Have you tried removing it to see if there is an improvement?

[Monkeytofu]

Originally Posted by DaBlue1

If you sprayed carb cleaner into the ports on the back of carbs, there may be a very small possibility of damage.

How is the fuel level in the new filter when the bike is running? Have you tried removing it to see if there is an improvement?

I'll try removing it and testing with a normal tube. I haven't noticed anything extraordinary and the fuel level looks fine in the new filter.

I'll also try some new gas. I can check the diaphragms without taking the entire carb off right?

[Monkeytofu]

Diaphragms are in perfect condition, fuel line/ fuel filter don't make a difference, and the fuel itself turned out to be fine.

My starter relay died. I'm on the edge of giving up and taking it to a mechanic after I replace that.

I think I'm in way over my head at this point. I just wish there mechanics in my area that weren't total scams and actually showed me how they fixed things...

Edit: Ultra derp. My battery was almost totally discharged. However, my bike currently turns over then turns off almost immediately.

[Monkeytofu]

Update 3: Empty tank but fuel looked fine. However, fuel in my new fuel line was orange... Going to go buy some from a motorcycle store instead of an auto store. Hopefully that'll do something, but I'm still having major throttle issues.

[emoyer]

Originally Posted by Motofool

Those are not the proper sealers.

Ronayers has the part, which number is 16030-1007 and cost ~$26 each.

Improvised O-rings aren't substitute for those parts, IMHO, especially is they disintegrate in gasoline + ethanol.

.

you can also get a rebuild kit from murphs kits that contains 2 of the bowl gaskets, 2 of the float needles, and some other parts, for $35.