Cold Starting Issue - Choke circuit clogged in float bowl

Started by Cdnlouie, February 07, 2007, 04:12:30 PM

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Cdnlouie

Something to consider  :-\

In a recent carburetor restoration I noticed something that I had not been aware of before, and that is a hidden .5mm orifice at the bottom of the float bowl.  This orifice is found in the 5mm opening between the float chambers in the lower half of the carburetor (It is not the emulsion tube hole).  The carb top has a brass tube with another small opening in the bottom that goes into this column which holds fuel for the cold start under choke.

At the bottom of this tube (in the middle of the float chamber) is this .5mm orifice that draws fuel from the main jet chamber (which is located behind the brass 10mm head bolt). This orifice is particularly prone to clogging (check the brass tube as well).  You really need to force a wire through the hole and make sure it passes some carb spray afterwards and shine a light down into the tube to see it.  If this hole is plugged or restricted you will get little or no fuel from choking the motorcycle when you really need it in cold weather. In addition you may have one working well and the other not so well, which would result in too rich for one cylinder and too lean for the other.  One floods and the other just won't start, an ideal situation for a no start.

Many of the complaints made about cold-starting may well be related to a clogged or partially clogged choke fuel circuit. Once it gets warmer this is not a big issue so we tend to forget about it until the cold weather again.

***Please note that there are many other issues that affect cold-starting, not the least of a poorly charged battery, but priming (as suggested by many) makes sure there is fuel available for the choke circuit so this does seem to improve things for most people.

Keep your carbs clean, very clean!

Louie  ;)









Lucky

I think your talking about the one that, if you spray thru it, comes out the feed at the bottom of the bowl that is cut at a slight angle.  i'm too lazy to search for it, but i did a post on it last fall.  your right though, clean! clean! clean! 

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

Cdnlouie


I think we are on the same page Lucky,

When you are looking into the main jet cavity it is just in front of the brass main jet and on the right side.  It goes into the bottom of the bowl (to the right) and then when it starts up, it restricts to a .5mm orifice, then continues to where it meets the top bowl gasket (5mm opening).  It is a devil of a spot to make sure it is not clogged. This is all that supplies the choke circuit with fuel and if it is clogged it may get a bit of fuel and then starve itself after a brief kick or two especially in the cold weather.

It really needs a stiff wire to clean it out as I have noted several bowls with totally clogged orifices here.  Of course the carbs I was doing were in pretty bad shape.

Louie



Night Vision

nice timing there Louie...

I was just about to close up the front carb on one set I'm cleaning..

now I'm thinking about crackin the set I already cleaned to make sure that set is good too

thanks
if it ain't worth doing it the hard way....
it ain't worth doing it at all - Man Law
;D


if it ain't broke..... take it apart and find out why


don't give up.... don't ever give up - Jimmy Valvano

YellowJacket!

Vision Mantra # 136: A clean carb is a happy carb.
Vision Mantra #137:  A Rider of Vision with a clean and happy carb is a happy Rider of Vision

Good post Lou.

David


Living the dream - I am now a Physician Assistant!!   :-)