The answer is simple, FACT. Some of the cures are dispelled by most CBX’ers though. The late models came with a vacuum fuel shut off that is said to cause hard starting problems. The vacuum fuel valve shuts off the fuel supply when the motor isn’t running so gas cannot overflow and hydro-lock the number one cylinder. This only happens when the motorcycle is on its side stand and the intake valve is open. This also only happens when one or more of the needle valves leak and the over flow gas flows out the overflow tubes and back into the number one carburetors over flow tube. This happens because when the motorcycle is on its side stand the number one carburetor is lower than the over flow drain outlet.
The
vacuum fuel shut off is getting a bad rap in that it is blamed for hard staring
after the CBX has sat for awhile. I
for one vote BS. My friend Oren and
I have added them to our “79’s” with no ill affect at all. I use a clear blue fuel line and I can watch the fuel flow
when starting with empty carburetors. With
everything drained the fuel starts flowing as soon as I hit the start button.
It does take a few seconds for the float bowls to fill but the bike fires
right off as soon as the fuel gets there. Just
test your vacuum fuel shut off to be sure it is working and leave it on there. Honda knew what they were doing.
Another thing is just turn off your petcock every time you park your
motorcycle. It is a easy habit to
get into. It is much harder to
remember to turn it back on.
So
much for the preaching and onto what this article is all about.
Lets say your vacuum fuel shutoff valve is removed and or is not
functioning correctly and you forget to shut off your manual fuel valve and last
but not least your pride and joy is sitting on its side stand.
Talk about asking for trouble. There
is one other way that I found to help myself out and that is to build my own
carburetor overflow tubes. It just
takes a couple of bucks in parts and totally solves the problem.
I bought some rubber automotive vacuum tees and some small plastic
airline and within a few minutes made up two separate drain manifolds.
There is several different ways to do this so it is up to your own
desecration.
The
two drain manifolds can be installed without removing the carbs from the engine
but removing the old CBX carb drain manifold is another story.
You can unplug the stock manifold and leave it in place until you remove
the carbs at a later date. Below is
a picture of a drain manifold I made up just to give you all a idea as to what I
am talking bout “sorry for the poor picture”.
You will notice the three tees are joined together with two short pieces
of plastic airline and the long piece of airline goes to the existing carb drain
tube on top of the clutch housing. Two
of these 3/16” plastic tubes fit nicely into the existing drain tube.
You need two of these manifolds, one for each set of three carbs made in
reverse image of each other. The
small round o-ring on the left is a used oil filter o-ring that I cut off about a
¼” piece to plug off the extra tee opening.
The big coil is just my supply of 3/16” plastic airline that I use for
this project and my carb vent tubes that are between the carbs “but that’s
another story”. The white / green
box is how the tees come when I purchase them from my dealer.
Here
is the short list of what it takes to do the job.
Qty. 6 - 4mm x 4mm x 4mm Tee Connectors. (Au-ve-co Products) Santoprene Tee Connectors #16654
Qty. Approximately 3 Ft. 3/16 plastic air line.
(Parplexn 3/16” O.D. .025
wall 250 W.P.)
Qty. 1 Used CBX oil filter O-ring.