Motorbike Forums


Reply
Thread Tools Display Modes

Gas spewing from carb drain tubes

 
 
Matt Johnson
Guest
Posts: n/a
 
      03-15-2010, 10:12 PM
I ride a 1981 honda cb900c. Love the bike, but the other day i had
some starting difficulties. The problem was the choke cable had slid
down and popped out. Anyways, i fixed this, but to see what it was i
had to remove the carburetor. Now i put everything back together and
voila it starts up, but spews gas all over my garage floor... dad was
happy about the smell.

So i've done some research on this problem and it sounds like i did
something to my float valves. What did i do and how do i undo it?
 
Reply With Quote
 
 
 
 
paul c
Guest
Posts: n/a
 
      03-15-2010, 10:37 PM
Matt Johnson wrote:
> I ride a 1981 honda cb900c. Love the bike, but the other day i had
> some starting difficulties. The problem was the choke cable had slid
> down and popped out. Anyways, i fixed this, but to see what it was i
> had to remove the carburetor. Now i put everything back together and
> voila it starts up, but spews gas all over my garage floor... dad was
> happy about the smell.
>
> So i've done some research on this problem and it sounds like i did
> something to my float valves. What did i do and how do i undo it?


Maybe there was some debris in the passages or lines and it fell into
the openings and made the floats stick open or maybe they were already
somewhat sticky with gum. It might clear by tapping them with a
screwdriver handle or if you're energetic enough by bouncing the whole
bike from the rear of the seat.

Another mistake I make all the time is draining the carbs before I take
them off and then forgetting to tighten the drain screws, that has
similar effect.
 
Reply With Quote
 
paul c
Guest
Posts: n/a
 
      03-15-2010, 10:44 PM
paul c wrote:
> Matt Johnson wrote:
>> I ride a 1981 honda cb900c. Love the bike, but the other day i had
>> some starting difficulties. The problem was the choke cable had slid
>> down and popped out. Anyways, i fixed this, but to see what it was i
>> had to remove the carburetor. Now i put everything back together and
>> voila it starts up, but spews gas all over my garage floor... dad was
>> happy about the smell.
>>
>> So i've done some research on this problem and it sounds like i did
>> something to my float valves. What did i do and how do i undo it?

> ...


If the other thoughts don't work right away, I'd just get it outside,
stub my cigarette and then look closely to see where the leak starts,
maybe the hose is leaking at the petcock or above the carbs (I know you
mentioned only one carb but I presume you have four of them) where the
fuel line splits.
 
Reply With Quote
 
`
Guest
Posts: n/a
 
      03-15-2010, 11:02 PM
On Mar 15, 3:12*pm, Matt Johnson <mouche.librem...@gmail.com> wrote:

> So i've done some research on this problem and it sounds like i did
> something to my float valves. What did i do and how do i undo it?


I suppose there may be carburetors in which you can install the floats
upside down...

If you have to remove the carbs to check the float level, there will
be a tiny wear mark on the tab that pushes the float valve closed.

If you've somehow installed your floats upside down, you'll see that
little wear market facing you...

 
Reply With Quote
 
paul c
Guest
Posts: n/a
 
      03-15-2010, 11:42 PM
paul c wrote:
> paul c wrote:
>> Matt Johnson wrote:
>>> I ride a 1981 honda cb900c. Love the bike, but the other day i had
>>> some starting difficulties. The problem was the choke cable had slid
>>> down and popped out. Anyways, i fixed this, but to see what it was i
>>> had to remove the carburetor. Now i put everything back together and
>>> voila it starts up, but spews gas all over my garage floor... dad was
>>> happy about the smell.
>>>
>>> So i've done some research on this problem and it sounds like i did
>>> something to my float valves. What did i do and how do i undo it?

>> ...

>
> If the other thoughts don't work right away, I'd just get it outside,
> stub my cigarette and then look closely to see where the leak starts,
> maybe the hose is leaking at the petcock or above the carbs (I know you
> mentioned only one carb but I presume you have four of them) where the
> fuel line splits.


eg., if three carbs are sucking and one has a loose connection, it might
not be a stuck float at all.
 
Reply With Quote
 
The Older Gentleman
Guest
Posts: n/a
 
      03-16-2010, 07:05 AM
Matt Johnson <(E-Mail Removed)> wrote:

> So i've done some research on this problem and it sounds like i did
> something to my float valves. What did i do and how do i undo it?


You've got a stuck float. Unless you actually pulled the carb apart you
didn't do anything. It just happens, especially on older Hondas.

Recommended fix: pull the carb bank, invert, remove float bowl from
offending carb, remove float pin and float, check for wear on pin,
replace with new pin if necessary, reasseble.

Quick & easy fix: locate offending carb, and give float bowl a sharp tap
with (for example) the wooden shaft of a hammer. Frequently this just
frees the float off.


--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ER GN250 Damn, back to six bikes!
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com
 
Reply With Quote
 
Matt Johnson
Guest
Posts: n/a
 
      03-16-2010, 10:47 PM
On Mar 16, 2:05*am, totallydeadmail...@yahoo.co.uk (The Older
Gentleman) wrote:
> Matt Johnson <mouche.librem...@gmail.com> wrote:
> > So i've done some research on this problem and it sounds like i did
> > something to my float valves. What did i do and how do i undo it?

>
> You've got a stuck float. Unless you actually pulled the carb apart you
> didn't do anything. It just happens, especially on older Hondas.
>
> Recommended fix: pull the carb bank, invert, remove float bowl from
> offending carb, remove float pin and float, check for wear on pin,
> replace with new pin if necessary, reasseble.
>
> Quick & easy fix: locate offending carb, and give float bowl a sharp tap
> with (for example) the wooden shaft of a hammer. Frequently this just
> frees the float off.
>
> --
> BMW K1100LT *Ducati 750SS *Honda CB400F *Triumph Street Triple
> Suzuki TS250ER GN250 *Damn, back to six bikes!
> Try Googling before asking a damn silly question.
> chateau dot murray at idnet dot com


checked it out and gas is leaking from all four drain tubes. i turned
the drain screws all the way around the opposite direction, but that
didnt change anything. ill take the carb off and try to post some pics
tonight.
 
Reply With Quote
 
`
Guest
Posts: n/a
 
      03-17-2010, 12:51 AM
On Mar 16, 3:47*pm, Matt Johnson <mouche.librem...@gmail.com> wrote:

> checked it out and gas is leaking from all four drain tubes. i turned
> the drain screws all the way around the opposite direction, but that
> didnt change anything.


The float bowl drain screws are not a two-position affair, you have to
tighten them all the way to stop gasoline from leaking out the four
drain tubes.

The float bowl drain screws just have a cone shape on the end which
stops gasoline from leaking out when you tighten them all the way
clockwise.

But there is a little rubber o-ring on each screw which may have
perished from age, they are at least 29 years old, yannow.

The o-rings are part of a gasket set that you probably don't want to
buy at the price. You can get new o-rings for a few cents each at a
good hardware store.

http://www.bikebandit.com/assets/sch.../H00840036.gif

1: GASKET SET 216212-001 $39.56

13,14,18,19 TUBE, FUEL are the float bowl drain tubes

The float bowl drain screws come with the float bowl. If the conical
ends of the
float bowl drain screws are all pitted and corroded, you can chuck the
screw in an electric drill and hold the conical end against a piece of
sandpaper or a whetstone, turn on the drill and manufacture a new
conical end the isn't pitted.

If the floats are stuck, gasoline will come up through the float bowl
air vents.

Most carbs I've worked on have an air vent for each float bowl or, in
the case of four cylinder engines, one float bowl vent between each
pair of carbs.

Your carburetors only seem to have one float bowl air vent though:

http://www.bikebandit.com/assets/sch.../H00840034.gif

19: TUBE 224256-001 $6.04



 
Reply With Quote
 
paul c
Guest
Posts: n/a
 
      03-17-2010, 02:15 AM
Matt Johnson wrote:
> On Mar 16, 2:05 am, totallydeadmail...@yahoo.co.uk (The Older
> Gentleman) wrote:
>> Matt Johnson <mouche.librem...@gmail.com> wrote:

....
> checked it out and gas is leaking from all four drain tubes. i turned
> the drain screws all the way around the opposite direction, but that
> didnt change anything. ill take the carb off and try to post some pics
> tonight.


Still puzzles me that only one 'carb' is mentioned. Also, I find it
hard to believe that all four drain tubes are leaking unless all four
drain screws are open. Seems unlikely that four separate float needles
would suddenly be blocked or stuck unless the carbs had been
dis-assembled and put back together wrong whereas the original post said
they were only removed. Also if the drain screws are turned all the way
out (counterclockwise), I'm pretty sure they will fall off! I wonder if
the above is talking about tubes above the carbs and screws not on the
float bowl.

 
Reply With Quote
 
The Older Gentleman
Guest
Posts: n/a
 
      03-17-2010, 07:10 AM
Matt Johnson <(E-Mail Removed)> wrote:

> checked it out and gas is leaking from all four drain tubes. i turned
> the drain screws all the way around the opposite direction, but that
> didnt change anything. ill take the carb off and try to post some pics
> tonight.


I think the simplest solution is probably the most accurate. You haven't
tightened up the drain screws properly.

Krusty's right when he says O-rings deteriorate with age, but for all
four to go at the same time? Nah.

--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ER GN250 Damn, back to six bikes!
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com
 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT. The time now is 07:01 AM.

1 2 3 4 5 6 7 8 9