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SCREAMIN' EAGLE PRO XL PERFORMANCE CYLINDER HEADS
J036082006-09-25
GENERAL
Kit Number
16677-05
Models
This kit fits all 1992 through 2006 XL 1200 models.
Additional Parts Required
This kit requires the separate purchase of Perfect Fit Pushrod Kit 18424-06, which is available from a Harley-Davidson dealer.
Top End Overhaul Gasket Kit must also be purchased separately and is available from a Harley-Davidson as follows:
  • 1992-2003 models use Kit 17032-91.
  • 2004-2006 models use Kit 17049-04.
WARNING
Rider and passenger safety depend upon the correct installation of this kit. Use the appropriate service manual procedures. If the procedure is not within your capabilities or you do not have the correct tools, have a Harley-Davidson dealer perform the installation. Improper installation of this kit could result in death or serious injury. (00333b)
NOTE
This instruction sheet references Service Manual information. A Service Manual for your model motorcycle is required for this installation and is available from a Harley-Davidson dealer.
Each head requires one 12 mm spark plug.
  • With Stock pistons, use Screamin' Eagle® Performance Spark Plugs (32320-91).
  • With High Compression pistons, use Screamin' Eagle Performance Spark Plugs (32321-91).
Recommended Parts
H-D recommends the use of Exhaust Flange (65328-83) to aid in exhaust headpipe re-installation. The headpipes should also be disassembled from the mufflers when attempting to re-assemble the exhaust system to the engine and motorcycle. The exhaust flanges can be purchased from a Harley-Davidson dealer.
Kit Contents
See Figure 2 and Table 1.
INSTALLATION
NOTE
This kit is intended for High Performance or Racing applications only and is not legal for sale or use on pollution controlled motor vehicles. This kit may reduce or void the limited vehicle warranty. Engine related performance parts are intended for the experienced rider only.
Due to the increased compression ratio, gasoline with a rating of at least 91 Octane must be used. The Octane Rating is usually displayed on the gas pump.
NOTICE
Do not exceed the maximum safe RPM specified below under any conditions. Exceeding the maximum safe engine RPM can result in equipment damage. (00248a)
NOTE
The valve springs in these cylinder head assemblies work with cams with up to 0.575 in. (14.61 mm) lift, and up to 7000 rpm.
1. Remove the existing cylinder head assemblies. Refer to the ENGINE section of the Service Manual for all removal and disassembly procedures.
NOTE
It is important to check valve-to-piston clearance as described in the following steps. We recommend that this inspection be performed by a Harley-Davidson dealer.
Valves must be properly adjusted to zero valve lash when claying pistons.
2. Apply a 1/8 in. (3.2 mm) thick layer of clay to the crowns of both pistons (in the areas where the valves meet the pistons).
3. Install the new cylinder heads from this kit per the Service Manual procedures, using the new gaskets from the Top End Overhaul Gasket Kit (purchased separately). Assemble the heads and valve train, and tighten the internal-threaded cylinder screws to the torque specifications listed in the Service Manual.
4. Turn the engine (by hand) through two complete revolutions.
5. Remove the heads and measure the clay at its thinnest point.
NOTE
  • Clay must measure 0.080 in. (2.03 mm) at the thinnest point. If this measurement does not meet the minimum thickness, the depth of the valve notches must be increased; however, the depth of the notches must not exceed 0.135 in. (3.43 mm).
  • Since oversized valves are used, radial clearance should also be checked. Radial clearance of 0.050 in. (1.27 mm) is recommended.
NOTE
The valve springs on the new cylinder heads have an installed spring height of 1.950 in. (49.5 mm), which equals 170 lbs (77.1 kg) of seat pressure.
  • To increase seat pressure, place shims 18224-98 (0.015 in.) or 18225-98 (0.030 in.) under lower spring collars. Each 0.015 in. (0.38 mm) spring height reduction equals 3.8 lbs (1.7 kg) more seat pressure. Shim to the desired seat pressure by placing shims under the lower collar, but maintain a minimum of 0.70 in. (17.78 mm) travel to coil bind.
  • To decrease seat pressure, machine the surface of the cylinder heads in the area under the lower spring collar. Every 0.015 in. (0.38 mm) increase in spring height equals 3.8 lbs (1.7 kg) less seat pressure. Machine to the desired seat pressure by machining the spring pockets in the cylinder heads, but maintain a minimum of 0.70 in. (17.78 mm) travel to coil bind.
For constant operation at extreme RPMs, all four valve springs should be checked for matched, installed heights.
1Upper collar
2Lower collar (with valve guide seal)
3Installed spring height 1.950 in. (46.23 mm); spring pressure 170 lbs (77.1 kg)
4Free travel should be at least 0.080 in. (2.03 mm) greater than maximum valve lift.
Figure 1. Valve Spring Travel
6. Change installed valve spring height (seat pressure) as follows:
a. Compress valve springs and remove valve collar retainers, upper collars, springs, and lower collars/valve seals on all four valves.
b. See Figure 1. Use shims or machine cylinder heads as required to obtain desired seat pressure (see notes above). Install lower valve spring collars (without valve guide seals), valve springs, upper collars, and collar keys. Check installed spring height.
c. If spring heights still do not match, repeat Steps 2a and 2b above as necessary to reach the desired installed spring height, again without installing valve guide seals.
d. When all spring heights match, remove valve collar retainers, collars, and springs. Install using new lower collars/valve guide seals 18016-03, purchased separately. Assemble the cylinder head assemblies.
7. Install new cylinder heads. Refer to the ENGINE section of the Service Manual for all assembly procedures.
NOTE
For 1992-2003 models, use the upper front engine mount (12) supplied in the kit when assembling the engine.
For 2004-2006 models, assemble the engine using the original front engine mount.
8. Check assembled engine for proper installation and operation.
SERVICE PARTS
Figure 2. Service Parts: Screamin' Eagle Pro XL Performance Cylinder Heads
Table 1. Service Parts: Screamin' Eagle Pro XL Performance Cylinder Heads
Kit
Item
Description (Quantity)
Part Number
Kit 16677-05
Black
1
Mount, engine front upper (1992-2003 models)
16689-05
2
Cylinder head assembly, rear (not shown, includes Items 3 through 10)
16657-05
Cylinder head assembly, front (shown, includes Items 3 through 12)
16655-05
3
  • Cylinder head (machined, with Items B, C and D installed)
Not Sold Separately
4
  • Collar, valve spring, upper (4) (available only as part of Item A)
Not Sold Separately
5
  • Collar and valve guide seal, valve spring, lower (4) (part of Item A)
18016-03
6
  • Stud, exhaust port (4)
16715-83
7
  • Intake valve (2)
18010-05
8
  • Exhaust valve (2)
18028-05
9
  • Retainer, valve collar (8) (also included with Item A)
18260-02
10
  • Valve spring (4) (available only as part of Item A)
Not Sold Separately
11
  • Medallion, Screamin' Eagle (front cylinder head only)
29508-05
12
  • Screw, button head, Torx (2) (front cylinder head only)
94634-99
The following items come installed in the cylinder heads, but are also available separately:
A
Screamin' Eagle Valve Spring Kit
18013-03A
B
Valve seat, intake
18020-83
C
Valve seat, exhaust
18011-86
D
Valve guide, intake and exhaust
16461-02