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**SFerinTEXAS** · 03-26-2011, 10:07 AM

Next time this happens take the lower airbox off, You can stick your hand up inside each carb tube and see which carb or carbs are backflowing (wet). That's the next clue you need.

**DGXSER** · 03-26-2011, 10:30 AM

Originally posted by Redshirt View Post

Could this possibly be from a sinking float?

Yes it could, if the float is sinking, then obviously it will not float (I know, thanks Mr. Obvious!!) and will not pressure the valve into the seat to stop the flow of fuel.

Originally posted by Redshirt View Post

It occured to me that if the octi is working from tank to octi, but the lines still have gas in them, if I have a sunk float, it would drain the fuel in the line from octi to carb(s) and thus into the airbox.

First off, understand that the Octi, and the petcocks are similar to the shutoff valves under the sink on your kitchen faucet. If the faucet is dripping, you can shut the valves below, but does not change the fact your faucet drips and needs to be repaired. The real issue remains the faucet, or in this case, float valves and or floats.

As to gas draining from lines with the valves shut, only if there is a path for air to get into the lines. Similar to putting your finger over the end of a straw that is in your drink and then pulling it out, the fluid stays in the straw because no air can get in to replace the fluid.

Also, the fuel level in the float bowl is not dropping when fuel flows into the air box, its like leaving the faucet run into a bucket, it is just way to full and over flowing.

Originally posted by Redshirt View Post

The difficult start MAY be from low float bowl level after drained into airbox(?). And giving it throttle to fill the bowl(s) back up may be the cause??

Ok, the throttle on these carbs do nothing to fuel level. The throttle controls air flow only. The amount of air flow controls how much vacuum is created across the venturi (middle smaller part where the slide is) of the carb body and that controls how much fuel is drawn from the bowls. So the most likely thing is that your float bowl is way to full causing a very rich mixture, and your opening the throttle adds air to lean the mixture out.

again, the fuel going into the air box is because the float bowl is way past full and is flowing over the top.

Since you mentioned sinking floats, you seem to have the older style carbs. Those have the vent Ts, and you want to be sure that vent passage is open or the they will flood no matter how good your floats and valves are.

**DenyP** · 03-26-2011, 10:45 AM

Your pet cock(s) and octy are letting fuel pass to the carbs when shut off and one or more needle and seats are leaking. I would solve the pet cock leak first. You wouldn't be the first guy to rebuild them and still have them leak.

Deny

**Redshirt** · 03-26-2011, 11:32 AM

Deny, I tested the tank petcocks while I had the tank off the bike. All positions worked as expected without leaking. The octi, however, I have no clue how to test.
Is there a way to test the octi by itself?

Vent T's are clear and unobstructed.

**crazy steve** · 03-26-2011, 11:45 AM

Testing the petcocks and octi is simple; with the motor off and the petcocks 'off', disconnect the fuel lines at the carbs. If gas runs out (after the initial fuel in the lines is gone), the petcocks and octi are leaking. If not, turning the petcocks to 'on' (motor still off) and now you get leaking, the octi is bad. The fact remains, even if one or both are leaking, the carb needle valves should still prevent fuel overflow, so there's an issue in the carbs too.

**Redshirt** · 03-26-2011, 12:29 PM

crazy steve,
that carb issue: Im going to test the floats for leaks. Is there anything else I can check for in the carbs that could contribute to the problem?

**DGXSER** · 03-26-2011, 12:57 PM

If the vents are clear, the float needle valves and seats are clean/new, and your sure the seal at the seat be it the washer for the older style or the o-ring on newer style is good. Then something is getting in there and clogging the valve some how.

I completely rebuilt the carbs on Thunderstruck, my first XS11, and no matter what one needle valve would leak. In my case, it was the soft rubber fuel line chaffing off when I attached it to the carbs and small pieces would plug my needle valve on one carb or another.

Your case may well be the float. With all the other items addressed, I would certainly go there next.

**fredintoon** · 03-26-2011, 01:04 PM

Originally posted by Redshirt View Post

The octi, however, I have no clue how to test. - - - Is there a way to test the octi by itself?

Hi Redshirt,
yes there is a 2-step process and it always works.
1) Remove Octy.
2) Toss Octy into garbage can.
With the test completed, cap off the "prime" gas tap connections and the Octy's vacuum connection.
Run a gas line from each tap criss-cross to each carb tee to give you scope to use in-line gas filters.
If you can't remember to turn the gas off when you stop and on again when you start should you really be riding?

**Redshirt** · 03-26-2011, 01:25 PM

Thanks for the suggestion, fredintoon.
Im attempting to fix it before bypassing. It will help me understand this great ole bike better if I get its blood on my hands (and some of my own).
At some point, I figure the octi will get canned like many of you have done already.
As for my memory... I was going to say something but I forgot what it was.

**natemoen** · 03-26-2011, 03:10 PM

Originally posted by fredintoon View Post

If you can't remember to turn the gas off when you stop and on again when you start should you really be riding?

Don't try and tell me you have never left your petcocks on (i know you currently have a standard tank but I am just talking at some point in your great many of years of riding

).

**Jarion** · 03-26-2011, 05:20 PM

Redshirt,
You're not the only person with this issue...
I've been making sure the gas is off when I park .... for 11 years!
Two rebuilds on the carbs during that time period hasn't solved the problem yet.
At some point... it will bother me enough to do what you're doing.... however, for now I like my hair and want to keep it for a while longer.... even though it's not as dark as it once was.

JT

**Redshirt** · 03-26-2011, 05:28 PM

My needle seats werent very tight. I just tightened them and did a manual test, touching the floats on and off with gas flowing. Messy, but I see the valves working.
I may go forward and put the carbs back on and see if that helps. Gas was getting past the valves before and the seat may have been the problem. I dunno.
Gotta change the oil as a precaution before riding.

**petejw** · 03-26-2011, 06:29 PM

have u got the occy plumped up correctly?
im with fred tho with ditching the thing, its
a pain at the best of times, but you do need to make
sure that the needle and seats are closing the fuel off,
if the fuel flows forward back into the motor it can become
an expensive repair.

when u have the carbs off, flip them upside down and place
ur mouth over 1 of the inlets at a time and blow,
move the floats up and down
u'll feel and hear if any of the needles arent sealing,
do this again with the float bowls fitted to see if the floats are
sticking on the gaskets.
the only thing this wont check is if the floats have holes in them
and are sinking.

**fredintoon** · 03-26-2011, 09:06 PM

Originally posted by natemoen View Post

Don't try and tell me you have never left your petcocks on - - -

Hi Nate,
yes, and I admit, more than once. Plus not remembering to turn them on again.
With my Standard gas taps converted to manual operation the 4 carbfulls will just get me to the first traffic light away from my house before the engine starts to falter and that's when I ask myself:-
If you can't remember to turn the gas off when you stop and on again when you start should you really be riding?

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airbox with fuel question

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