TROUBLESHOOTING THE S&S CARB
 
ENGINE PROBLEM
PROBABLE CAUSES
FIXES
       
1
Carb runs rich at slow engine
speeds sometimes with black
smoke from exhaust but okay
at higher engine speeds.
1. Enrichener (choke plunger) is
being held open by sticking lever
or nearby hardware.
2. Enrichener is not seating. If
plunger face hits bottom of well
before small cone on plunger does
fuel will be drawn out of bowl  
3. Idle mixture screw out of
adjustment.
4. Air filter dirty or restricted.
5. Carb body where idle mixture
screw comes into butterfly area is
cracked from turning screw in too
far. Unable to adjust idle mixture
correctly.
1. Remove obstructions and make
sure plunger (enrichener) is free
to close.
2. Bottom of enrichener well will
need to be machined lower to form
a new seat for plunger cone. Call
Triple X Carbs for this fix.   
3. Reset idle mixture screw. Turn
in screw gently until it stops, do
not use excessive force or carb
body will be damaged. Turn screw
out 2 turns for a starting point.
Warm up engine. With engine
idling adjust screw in or out in
small increments until a smooth
idle is obtained then back out
screw slightly.   
4. Replace or clean air filter,
remove restrictions.
5. Call Triple X Carbs for repair
info.
2
Engine idles but when trying to
accelerate engine falls on it's
face, pops and sputters and
almost dies. Engine will not run
above idle.
1. Carb bowl vent covered up or
restricted. Small 1/4 inch hole on
carbs far left face as you look at
the front of carb must be open to
atmosphere. This passage is
usually vented inside the air
cleaner assy. When changing to a
new style air cleaner make sure
this carb vent hole is not covered
up by a gasket or backing plate.   
1. Check air cleaner backing plate
to make sure carb vent hole is
open. Install proper gasket with
hole to match carb vent hole.
3
Engine idles and runs fine
when opening the throttle
slowly but when opening
quickly the engine hesitates
and stumbles for a moment
then accelerates.
1. Accelerator pump screw out of
adjustment. (not enough fuel squirt
when opening throttle) Screw
located near end of throttle shaft,
right side as you look at front of
carb,
2. Accelerator pump nozzle located
inside venturi behind main fuel
tube or Booster is restricted with
dirt not allowing an extra squirt of
fuel when opening throttle.
3. Idle mixture screw out of
adjustment
4. Intermediate jet too small. This
jet along with the idle mix setting is  
primarily used up to about
3000-3500 rpm. If spark plug
inspection shows a white lean
condition then jet size is too small.   
1. Turning accelerator pump
adjustment screw in gives less fuel
squirt and backing screw out gives
more fuel squirt when opening
throttle.  
2. Brass nozzle tip can be cleaned
when fuel bowl is removed. Use a
.004 feeler gage blade (do not
use a razor blade or knife blade
as tip will be damaged) and pass it
through nozzle slot. Then using
the carbs pump rod, pump fuel
through nozzle by hand until a
good stream is obtained.
Reassemble bowl on carb and
re-adjust pump screw. A starting
point is when 1 or 2 threads of the
tip of the pump screw is showing
through carb boss.
3. Adjust idle mixture as shown
above, problem #1-fix #3     
4. Int jets available in .025, .0265,
.028. ,0295, .031, .032, .033, ,036
and .040.
 
Engine runs fine but cruising
down down the highway it
coughs or hiccups through the
carb once in a while
1. Intermediate jet too small
2. Spark plugs, wires or coil
breaking down.
3. Spark plug heat range too hot
4. Valve sticking.
1. Go up a size on the int. jet.
Available sizes; .025, .0265, .028,
.0295, .031, .032, .033, .036, .040
2. Replace defective parts.
3. Change to a cooler heat range
plug.
4. Try adding an oil additive such
as Marvel Mystery Oil (sold at auto
parts stores) works great to free
up valves and rings plus when
added to fuel it will clean carb
passages.
 
Engine has a decel popping in
exhaust
1. Engine idle mixture screw set too
lean
1. Adjust idle mixture screw out 2
to 2-1/8 out. Due to exhaust and
cams the normal mixture setting
may not work.
 
Unable to adjust idle mixture,
screw is all the way in but
engine continues to run.
1. Fuel being drawn into engine
from another source. The most
likely place is the enrichener. If
enrichener is being held open by
linkage engine will run rich. If
plunger face hits the bottom of well
before the small cone on plunger
does fuel will be drawn into engine
and run rich.
2. Fuel level in bowl too high
3 'O' ring missing on accelerator
pump nozzle.
4. Idle mixture screw hole possibly
cracked in butterfly bore from
turning screw in too far .
1. Adjust enrichener lever or
remove cause that holds
enrichener open.
Machine enrichener well face
slightly to lower face and allow
plunger cone to seat first.
2. Fuel level should be about
5/16" below bowl parting surface.
3. Install new 'O' ring.
4. Carb can be repaired only at
Triple X Carburetors. S&S will want
you to buy a new carb body at
over $200.
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