98 Fatboy Service Manual

TROUBLESHOOTING 3.11
DIAGNOSING VALVE TRAIN NOISE
To diagnose and correct noisy hydraulic lifters and valve train
components, use the following procedures:
1. With engine and oil at normal operating temperature,
check oil pressure at 2000 RPM. If oil pressure is above
50 PSI (345 kN/m2) or below 5 PSI (34 kN/m2), inspect
oil pump, crankcase passages, and oil hoses for restrictions
or blockage. Repair or replace parts as necessary.
2. If oil is reaching the hydraulic lifters, remove and inspect.
See LIFTER INSPECTION under 3.22 PUSHRODS,
LIFTERS AND COVERS. Clean lifter bore of all foreign
material. Replace hydraulic lifter if required.
3. Examine push rod, lifter and lifter block for proper fit and
any signs of unusual wear. Replace parts as necessary.
4. Visually inspect camshaft lobes for abnormal wear.
5. Remove camshaft and pinion gear, clean and inspect for
wear and fit. Measure pitch diameters and check for outof-
round condition. Replace parts as necessary.
6. Check cam chain tensioning spring and shoe for wear.
7. Remove cylinder head and rocker box assemblies.
Check rocker arm end play and check for binding.
Inspect valve stems for scuffing and check stem to guide
clearance. Check valve seats for signs of looseness or
shifting.
8. Grind valves and valve seats.
COMPRESSION TEST
NOTE
The Twin Cam 88B engine uses a 12 mm adapter with the
compression gauge.
Satisfactory engine performance depends upon a mechanically
sound engine. In many cases, unsatisfactory performance
is caused by combustion chamber leakage. A
compression test can help determine the source of cylinder
leakage. Use CYLINDER COMPRESSION GAUGE (Part No.
HD-33223-1) that has a screw-in type adapter.
A proper compression test should be performed with the
engine at normal operating temperature when possible.

CYLINDER LEAKAGE TEST
The cylinder leakage test will pinpoint engine problems including
leaking valves, worn, broken or stuck piston rings and
blown head gaskets. The cylinder leakage tester applies compressed
air to the cylinder at a controlled pressure and volume
and measures the percent of leakage from the cylinder.
Use CYLINDER LEAKDOWN TESTER (Part No. HD-35667-
A) and 12 mm adapter and follow the specific instructions
supplied with the tester.
The following are some general instructions that apply to Harley-
Davidson V-twin engines:
1. Run engine until it reaches normal operating temperature.
2. Stop engine. Clean dirt from around spark plugs and
remove the spark plugs.
3. Remove the air cleaner and set the throttle to the wide
open position.
4. The piston in the cylinder being tested must be at top
dead center of compression stroke (both valves closed)
during the test.
5. To keep the engine from turning over when air pressure
is applied to the cylinder, engage transmission in fifth
gear and lock the rear brake.
NOTE
Before performing the cylinder leakage test, verify that the
tester itself is free from leakage to obtain the most accurate
test results. With a soap solution [applied around all tester fittings],
connect the cylinder leakdown tester to the compressed
air source and look for any bubbles that would
indicate leakage from the tester.
6. Following the manufacturer's instructions, perform a cylinder
leakage test on the front cylinder. Make a note of
the percent of leakage. Leakage greater than 10% indicates
internal engine problems.
7. Listen for air leaks at carburetor intake, exhaust pipe,
and head gasket. Air escaping through the carburetor
indicates a leaking intake valve. Air escaping through the
exhaust pipe indicates a leaking exhaust valve.
NOTE
If air is escaping through valves, check for correct push rod
length.
8. Repeat procedure on rear cylinder.
NOTE
After installing spark plugs, be sure that throttle plate is in the
closed position before starting the engine.
DIAGNOSING SMOKING ENGINE OR
HIGH OIL CONSUMPTION
Perform COMPRESSION TEST or CYLINDER LEAKAGE
TEST as described. If further testing is needed, remove suspect
head(s) and inspect for the following:
Check Prior To Cylinder Head Removal
1. Oil tank overfilled.
2. Oil carryover.
3. Breather hose restricted.
4. Restricted oil filter.
Check After Cylinder Head Removal
1. Oil return passages for clogging.
2. Valve guide seals.
3. Valve guide to valve stem clearance.
4. Gasket surface of both head and cylinder.
5. Cylinder head casting's porosity allowing oil to drain into
combustion chamber.
6. O-ring damaged or missing from oil pump/crankcase
junction.

CYLINDER HEAD
1. See Figure 3-23. Following the sequence shown, alternately
loosen the six rocker housing bolts. Remove
rocker housing bolts and their captive washers.
2. Remove rocker housing and gasket. Discard gasket.
CAUTION
To prevent distortion of the cylinder head, cylinder and
cylinder studs, gradually loosen the cylinder head bolts
in the specified sequence.
3. See Figure 3-24. Remove cylinder head bolts.
a. Following the sequence shown, alternately loosen
each of the four cylinder head bolts just 1/4 turn.
b. Continue turning the bolts in these increments until
loose.
c. Remove the cylinder head bolts.
4. See Figure 3-25. Remove cylinder head and head gasket
(2). Discard gasket.
NOTE
Save the cylinder head gasket (if salvageable) and ring dowel
O-rings for use with the CYLINDER TORQUE PLATES (Part
No. HD-42324-A) when measuring, boring or honing of the
cylinder is required.
5. See 3.23 CYLINDER HEAD for inspection and repair
information.
Figure 3-21. Push Rod Locations

CYLINDER
1. Raise the cylinder just enough to place clean shop towels
under the piston. This will prevent any dirt or debris,
such as broken ring pieces, from falling into the crankcase
bore.
CAUTION
Exercise caution to avoid bending the cylinder studs.
Even a slight bend or nick can cause a stress riser leading
to stud failure.
2. Carefully remove the cylinder. Exercise caution to avoid
bending the cylinder studs. As the piston becomes free
of the cylinder, hold it upright to prevent it from striking
the studs or dragging across the stud thread area.
3. Slide approximately 6.0 in. (152 mm) of plastic tubing,
rubber hose or conduit over each cylinder stud. Use
material with I.D. of 0.5 in. (12.7 mm) to protect cylinder
studs and piston from damage.
4. See Figure 3-25. Remove O-ring seal (4) from the bottom
of the cylinder liner. Discard O-ring seal.
5. See Figure 3-26. Remove O-ring from ring dowel (4) on
base of cylinder deck. Discard O-ring.
6. See 3.24 CYLINDER for inspection and repair information.
PISTON
1. Verify that clean shop towels are properly positioned
over the crankcase bore to prevent the piston pin circlip
from falling into the crankcase.
1WARNING
Wear safety glasses or goggles when removing or installing
retaining rings. Retaining rings can slip from the pliers
and could be propelled with enough force to cause
serious eye injury. (00312a)
2. See Figure 3-26. Remove the piston pin circlip.
a. Insert the PISTON PIN CIRCLIP REMOVER/
INSTALLER (1) (Part No. HD-42317-A) into the piston
pin bore. Position claw on tool in slot of piston (2)
(directly under circlip).
b. Hold a shop towel over the piston pin bore in case a
circlip should fly out during removal. Squeeze the
handles of the tool together and pull from bore.
Remove circlip from claw and discard.
NOTE
It is not necessary to remove both piston pin circlips during
piston removal. Leave the second circlip in the pin bore.
3. See Figure 3-27. Remove the piston pin. If piston pin is
difficult to remove, use PISTON PIN REMOVER (Part
No. HD-42320-A).
a. Remove acorn nut and spacer from rod end of tool.
b. Slide rod end through piston pin. Install spacer and
acorn nut (1) on end of rod.
c. Position rubber-coated tips (2) of tool on flat each
side of pin bore.
d. Turn handle (3) in a clockwise direction until piston
pin is pulled free of bore.
4. Remove the piston. Be sure to hold the connecting rod
shank upright to prevent it from striking the crankcase.
Place a 3.0 in. (76.2 mm) long piece of foam-type water
pipe insulation around each connecting rod. Use material
with an O.D. of 2.25 in. (57.1 mm) and an I.D. of 1.0
in. (25.4 mm) to prevent damage.
5. Turn the piston over. Mark the pin boss with the letters
'F(ront)' or 'R(ear)' to identify location.
6. Service as needed. See the following topics for inspection
and repair information.
a. See 3.25 PISTON.
b. See 3.26 UPPER CONNECTING ROD.
7. Complete engine work.
a. If performing a top end overhaul only, see 3.17 TOP
END OVERHAUL: ASSEMBLY.
b. If performing a complete engine overhaul, see 3.18
BOTTOM END OVERHAUL: DISASSEMBLY.
GENERAL
NOTE
It is assumed that each step performed on one cylinder is
automatically repeated on the other.
This section provides a sequential process for engine reassembly
after a complete 3.16 TOP END OVERHAUL: DISASSEMBLY.
If you reached this section after an inspection or
repair procedure, start where necessary and continue to the
end of the section.
● Piston installation-see below.
● Cylinder installation-see page 3-35.
● Cylinder head installation-see page 3-38.
● Push rods, lifters and covers installation-see page 3-41.
● Rocker arm support plate installation-see page 3-42.
● Breather assembly installation-see page 3-43.
PISTON
1. Slide approximately 6.0 in. (152 mm) of plastic tubing,
rubber hose or conduit over each cylinder stud, if
removed. Use material with I.D. of 0.5 in. (12.7 mm) to
protect cylinder studs and piston from damage.
2. Apply clean H-D 20W50 engine oil to piston pin, piston
bosses and upper connecting rod bushing.
3. Remove water pipe insulation from connecting rod
shank.
4. See Figure 3-28. Place piston over rod end so that the
arrow stamped at the top of the piston points toward the
front of the engine.
5. See Figure 3-29. Insert piston pin (1) through pin bore
and upper connecting rod bushing. Push pin until it contacts
circlip installed in opposite pin boss. Verify that end
gap (3) for circlip is 180 degrees from opening (2).
6. Place clean shop towels over the cylinder and lifter bores
to prevent the piston pin circlip from falling into the crankcase.
Verify that the circlip groove is clean and free of dirt
and grime.