#3 Carb is pouring out gas...

Well, I'm a complete newbie to this. I bought my bike, which had been sitting for a year or more, took out the carbs, took them apart, and cleaned them all up. I put them back together again with new gaskets, and low and behold, no "optional" pieces left over! Installed them, hooked everything up again, and when I turned the fuel to primary, gas started pouring out of the #3 carb. ARRGH!

I was watching it pour right out of somewhere in the middle. Presumably the air chamber. So, is this evidence of a sticking float? I checked them all when I put them back together, and they were all even. I didn't measure because I thought that they would still be ok since the bike was running before I took it apart. Anyway, the #3 float is not higher than the others.

Suggestions? Or do I get to start all over again?

BTW, I did check the drain screw. It is tight. All mixture screws are turned out approx. 2.5 turns from bottom. I haven't tried starting the bike. I didn't get a chance to before noticing the puddle of fuel under the bike.

TIA

 

You might just have to yank them again. Im not sure what you mean by the "air chamber" but it does sound like a stuck float, maybe something fell in during reasemble.
Also, synching the floats is easy enough when the rack is out anyway so you might want to give it a try, its good maintenance.

this would be obvious but did you loose the little needle that the float uses to plug the gas?

And if you close the tank, drain the bowl, wack the carb ( maybe unstick it) and refill does anything change. atleist then you would know it was a stuck float

 

It might just be stuck. Turn the fuel off and fire it up.

Once it starts to fuel starve turn the fuel back on while you tap the bowl with a hammer handle. See if it does it again.

 

Thanks for the tip. I'll give the "bowl whack" trick a shot. Quick question, though. How do I get at the inside carbs when I'm on the bike and it is running? Do I stick the handle down in there and hit the end of the hammer? Or do I rap on the sides of the carb assembly?

 

small hammer, back of a screw driver. rock attached to a stick... you dont need to hit it that hard. just let it run, get off, and reach into where you would adjust the idle

 

Well, thanks for all the tips. Looks like I have bigger problems, though. I tried to fire it up, and it took a lot of work and a lot of starts to get it to run, and I couldn't keep it running. If I let off on the throttle, it would immediately die. So, I'm going to go back to the drawing board.

 

I have had similar problems with mine and they were solved by:

Tough starting - enrichment circuit needed cleaned
Fuel running out - cleaned the diaphragm assembly better, including wet sanding the port with 1200 grit sandpaper
Dying with no throttle - adjust the idle adjustment knob (works best if carbs are bench synched properly)

 

When you were doing your carbs did you check the float height? It could be your bowls are over filling. I would think that or a sticky float needle. Another thing you should do is take some > fine grit sandpaper <* and sand the float pin and inside were the pin goes in the float. That would eliminate that from being a problem.

* "Fine grit sandpaper"

(Ultra-fine Wet-O-Dry Finishing Paper 1500 -or- 2000 Grit)

 

I don't know that sanding float valves and seats is such a good idea.

If they're not shutting off even when adjusted properly, it's better to replace them with quality parts. There are some aftermarket float valve kits out there that simply do not work; you never know what a PO installed.

 

I did not suggest sanding the needles and seats. I would not advise that either. Just the pin that holds the float and inside the float where the pin goes through the float. Also check for debris in seats that may prevent the needle from seating properly.

 

Thanks again for all the suggestions. I'm feeling a little less discouraged today.

The float bowl whack didn't seem to do it, so tonight I'll take it apart again and see what I can come up with. I'll dry measure the float heights and double check the needle valve. When I inspected everything, the needles were moving in and out pretty smoothly, but something might have gotten in there.

I did clean the enrichment circuit when I took them apart. I had good fluid flow and airflow through it when I was done, and I could see light at the bottom when I looked into it. I hope that isn't the problem.

Problem could be the idle adjustment. That didn't occur to me. As I mentioned, I've never done this before, and when I first took the carbs off, I think I twiddled with it a bit before realizing what it was... D'OH!

Float height on the Mikuni BC33 is 17.5mm? Is that measured to the bottom of the float? Or the seam?

 

I spoke with a buddy at work, and he told me how the idle adjustment screw and the throttle adjustment work together. I know when I put the carbs back, the butterflies were tight as a drum. You could almost hear them pop open when working the throttle linkage. I didn't realize that they were supposed to have a slight opening.

Now that I think about it, I remember reading about bench synching the carbs by using a strip of business card to determine the position of one butterfly, and adjust all others to hold a strip with similar tension.

So, I think that must be my starting issue. Man! It sucks to be ignorant! So, lesson #72: idle adjustment screw adjusts throttle stop to allow flow through butterflies.

Now, for that cursed float...

 

I had a problem with getting my float needles to seat. I bought brand new ones K&L brand and, my problem got worse! I finally had to dress the seats & needles with some very fine sand paper. I used 1000 grit wet/dry paper to smooth out the action on the needles. After I finished sanding all of the needle edges (all 4 edges) and, then rolling up the paper to fit inside the seats I was finally able to get them to stop leaking. One quick way to check if the seats are still leaking, set your carbs upside down on a level surface. Place the fuel inlet hose in your mouth & blow hard. Lift each float, you should hear air and a bit of fuel leak out of the needle/seat valve. Let go of the float while still blowing and, listen for the air to stop. If you still have a leak then, you still have a bit of dressing to do on that carb.

Cheers
Ken

 

The term "Sanding" is misused. Finishing is more appropriate.
With a tightly rolled-up section of 2000 Paper; the Float Valve Seat gets refinished and cleaned.
Not gouged or scratched.

Some of the New Float Pins might need a "Dressing-up" if the Tip is misaligned.
Old ones get shined-up and re-prettied.
New ones get a Final touch-up they should have gotten before getting bagged and sold.

File it under: Owner Quality Assurance. When you spend money for a Kit the Float Valve Body ought to be ready to go.

 

Thank you for clarifying that Rick, I didn't mean to nudge him towards gouging his Valve Seat. Sometimes I know what I'm talking about but I just don't know how to describe it...and sometimes I just don't know what I'm talking about . I've also used Scotch Brite pads to help remove varnish with no ill effects.

 

I have had to polish my seats also. Thing is, you aren't really polishing the seat where the needle actually plugs the hole. You are simply polishing the chamber walls so the needle doesn't stick as it goes up and down. I used a regular q-tip that I cut in half. Stuck the stick end in a dremel tool and used some Weenol metal polish. Flitz or any other kind of metal polish should work fine, as would toothpaste. As long as it is actually toothpaste like everyone used to sell. Not the new gel types.

 

On Non-OEM Replacement Float Kits, ... you should also "Eyeball" the Flot Pin Geometry.

L@@K at the Pin hanging-off the Tang.
On SOME, ...
The Wire attached to the Pin is NOT Centered.
Just hanging on the Float Tang makes the Pin "C0ck-eyed"

You either have to:
Move the Wire Hanger to the OTHER side of the Tang, ...
Or, ...
Re-shape the Hanger Wire so the Pin is Centered over the Valve Body.

(A pair of Stainless Steel Locking Forceps makes holding little things much easier especially if you don't like burning your fingertips)