S&S Cycle Head Bolts for 1984–12 Harley-Davidson Big Twin & 1986–12 Sportster Models User Manual

Page 2

Introduction

High performance engines often use cylinders which are longer or in some cases shorter than stock. In order to accommodate engines of different
cylinder lengths without using special cylinder studs, S&S® offers different length head bolts and two different thickness head bolt washers. The
combination of bolt lengths and washer thicknesses allows engine builders to compensate for different cylinder lengths as well as the difference
in head thickness in 1985–’90 and 1991–later Harley-Davidson® big twin and Sportster® models. Because of smaller bolt head diameter and size
of counterbore in head, S&S head bolts of correct length must be used with S&S four inch bore Super Sidewinder® engines and four inch bore
street cylinder heads.

Using incorrect head bolts may result in head gasket failure with possible damage to cylinder head, piston, or other engine parts.

Head gasket failure may cause substantial oil losses. Oil on tires or brakes can result in loss of control of motorcycle with serious injury
to operator and others.

Procedure

1. Before installing head bolts, verify that bolt kit is correct for engine. Consult the appropriate head bolt selection chart on page 4. To use chart,

find description of engine in column marked “Engine Displacement.” Chart will show part # of head bolt kit to be used with most common
engines if available. Chart will also show part number and length of long and short head bolts and part number and thickness of washer to be
used with each head bolt.

NOTE: S&S head bolt kits may include extra washers. Only one washer should be used per head bolt.

2. S&S recommends head bolt kit 93-3013 for custom engines and cylinder lengths not included in chart. Head bolts in kit 93-3013 are longest

available and can be cut to desired length because of full length internal threads.

S&S® recommends that thread engagement be .563", which is usually 1½ times stud diameter—stock studs are 7/8". See Figure 1. If you are

uncertain about sufficient engagement, you can calculate the engagement using the formula shown below.

NOTE: Other S&S head bolt kits do not have full length threads. If these bolts are cut shorter remaining threads may be insufficient to tighten head bolt

on cylinder stud.

CAUTION

WARNING

Figure 1

Add:

Cylinder Length
(Gasket surface to gasket surface measurement)

+B Base Gasket Thickness

+C Head Gasket Thickness

+ D or E

Cylinder Head Thickness
(Gasket surface to head bolt washer pad
measurement)

Short Side
All S&S®= 1.207"
Late 1985–’90 stock= 1.207"
1991–up= 1.405"

Long Side
All S&S= 2.700"
All Stock= 2.700"

+F Desired thread engagement— .563"

(Usually 1½ times stud diameter—stock studs are 7/8"

SUBTRACT:

Cylinder Stud Installed Height
(Crankcase deck to top of stud measurement)