Hi All,Getting to the end of my project trying to get the carb tuned. Carb was rebuilt and cleaned. Bike runs only when choke is pulled all the way out. I can move it back in maybe a third ...any more than that it stalls. I don't have clamps on the VOES line on either end ..maybe a vacuum leak? Came w/o clamps but guess that dosent mean anything. The small spring on the right side of the carb has play ...not sure if it's seated correctly. Is it supposed to be tight with no play at all? I pulled the plugs they were pretty back w carbon. Cleaned them and reinstalled. Thanks V

 

Suggest going here and review the choke (enrichner) transition along with other CV Carb tips: https://sportsterpedia.com/doku.php/techtalk:evo:carb02

Check manifold gaskets.

You may have the wrong size jets and or parts not put back correctly.

Did you do the carb rebuild?



"The CV40 uses a gravity-fed fuel supply through a float controlled inlet valve to fill a fuel supply bowl, from which the internal jets obtain fuel. It also has an enrichment system, mislabeled a choke. This provides a pathway for fuel to bypass most of the carb operation and be supplied directly into the manifold, at the rear of the carb, for better starting. There are air passages to the fuel pathways to mix the air and fuel together.

There are a number of parts that operate in combination to control the mixing of fuel & air into a combustible fuel mixture. The vacuum slide, needle, needle jet, emulsion tube, main jet, slow jet (with an emulsion tube), idle mixture screw, idle ports, tranfer ports and accelerator pump, all assist in this mixing operation over the range of operating conditions.

The purpose of the carburetor is to atomize fuel into the incoming air such that a proper air-fuel-ratio (AFR) is achieved for varying conditions. The Slow Jet (AKA Pilot Jet) & Main Jet each use an emulsion tube with a fuel orifice & air holes. Each emulsion tube pulls fuel from the float bowl reserve and is fed air thru small air ports (called air jets) on the face of the carb (filter side). In each case, the emulsion tube produces an air/fuel mixture that is further mixed with the air flowing into the venturi (carburetor throat).

The air flow is generally controlled by the Throttle Plate along with the vertically moving slide that essentially varies the venturi size to create a Constant Velocity of air (from which it gets it's name). By selecting various Slow and Main Jets, the AFR can be altered to produce a preferred ratio. Air flowing into the venturi creates a vacuum which pulls the air/fuel mixture from the emulsion tubes into the air stream.

To create a proper idle operation, the Idle Port (on the engine side of the throttle plate) has a separate adjustable screw (Idle Mixture Screw) that allows some of the mixture from the Pilot Jet emulsion tube to be bled directly into the manifold, bypassing the throttle plate.

As the throttle plate is opened, fuel is pulled from the Transfer Ports. With more throttle, fuel is pulled thru the needle jet, in greater quantity as the tapered needle is lifted out of the needle jet opening by the vacuum-operated slide.

The constant-velocity system provides a partial means of compensating for operation at different altitudes. In a fixed system, as altitude increases, the fuel mixture becomes richer due to the thinner air. But the CV system partially compensates for this fact because the vacuum-slide operation is also affected by the thinner air, thereby supplying less fuel into the mix to match the reduced air density.

The CV40 (1989-later) has an accelerator pump, controlled by a rod attached to the throttle cable cam, to provide additional fuel when the throttle is quickly opened for acceleration. It squirts raw fuel into the venturi throat to enhance the fuel mixture along with the quickly added air.

The stock carb has been adjusted to control exhaust emissions. The idle mixture is set at the factory and the adjusting screw is capped because it is not intended to be adjusted except by factory technicians. However, the cap can be removed and adjustments made as needed.


Make sure your needle jet is orientated correctly.




NOTE:
The above information, while credible, is worth what you paid for it and should not be considered gospel.
Do due diligence, research and have a H-D Field Service Manual before working on your bike.
You will probably have many opinions and suggestions presented; make sure you research the person providing the helpful information as there are some who provide good information that is useful and some who speak out of other orifices with gibberish. You will figure out this quickly.

 

Heads spinning a bit. Thanks...initially before any carb work it ran at a super high idle, I found the throat plate wasn't closed fully at idle. I rebuilt it and it ran ok. Then I pulled the engine off the frame to paint it. So after all is together I can't run it w/o the fuel enhancer engaged. I'll replace the voes line ...looks pretty old n ragged.

 

Sounds like your pilot jet is clogged. It feeds the idle and off idle circuit. Make sure the jet is clear and passages all blown out with carb cleaner.

John

 

^^^^^^^
this
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Did you replace the manifold to head o-rings and is the carb to manifold new?

 

Well I'm kind of getting there I think. Carb to manifold has a,1/4" hard gasket with a rubber o ring that faces the intake it was in good shape so it is reused but....I installed new vacuum hose on the VOES, started it with the fuel enhancer engaged then just tweeked the idle adj. and pushed the enhancer in more then tweeked etc...till I got idle at 970ish w/ enhancer off (by now I have oper. temp). as per SS Super E carb instructions. Then...went to mix screw CW till rough idle then CC till engine stumbled then set in-between those parameters...per instructions...then went to accel.pump screw and did the throttle business and adjusting so when rolling on throttle with no hesitation. I think it runs and sounds pretty good (not sure what that is ..new at this) the only thing... with rolling on the throttle if I do it with a somewhat less aggressive roll it doesn't hesitate if I do it fast there is a stumble the engine dosent follow. Also...quite a bit of white smoke 1st minute or so. Thanks V

 

Okay, it would have been helpful to tell us you had an S&S carb to begin with. I assumed we were discussing a stock CV40, since you never mentioned it being an aftermarket carb.

John

 

That would have saved a lot of time and posting of useless information to you.

 

I assumed the SS was stock. Also has the super jet mod. Apologies for that. Anything on the accelerator adj? V