EMULATOR FITTING REQUIREMENTS FOR MODELS
FOR PROPER FIT OF THE GOLD VALVE CARTRIDGE
EMULATOR THE FOLLOWING CONSIDERATIONS MUST BE CHECKED
FITTING the EMULATOR and MODIFYING the
- SELECT THE EMULATOR SIZE TO FIT INTO
THE FORK TUBE - The outer diameter
of the Emulator must be smaller than the inner diameter of the fork
tube by at least 0.75 mm (0.030"). It can be as much as 4 mm
(0.160") smaller. The OD is first dimension listed in the description.
- FIT IN / ON THE DAMPING ROD - Typically
there are two types of damping rods, cupped top and flat top. Please
keep in mind that a "perfect" seal is not required for optimum
performance. The main fork spring holds the Emulator down on top of
the damping rod. The Emulator can move around a bit without losing
- (fig 1) Most Japanese forks are cupped on top. This is the typical
installation for the standard Emulator (though some special models
are designed specifically for flat top). Before installation, check
the fit of the Gold Valve Emulator by placing it on the top of the
damping rod. The step on the Emulator must sit into the top of the
damping rod (D1 - fig 1) and have 0.5 mm (0.020") clearance
minimum. It can have quite a bit of clearance but it must completely
cover the opening in the end of the rod.
The dimensions of the step diameter are listed
second in the description. (Some models of Emulator come with a
sizing circlip to fit a wider range of diameters. In this case there
will be two diameters listed for step diameter.)
FLAT TOP - (fig 2)
The instructions for the Flat Top Style also covers damping rods
that have parts of the rod extending upward as well. Many older
model Ceriani, Betor, Bitubo, etc. forks are this type. A special
adapter must be manufactured for proper fit. As there are many different
styles here are some general instructions:
- Most adapters look like a straight sleeve
or tube. The adapter can be machined out of aluminum. It must
seat flat on the top of the damping rod. It does not have to locate
on the rod but it can, depending on the specific application.
- The Emulator step diameter should fit into
the adapter with about 0.5 mm (0.020") clearance. Put a generous
chamfer around the top of the adapter. This will allow the Emulator
to locate in the adapter more easily.
- The locking nut on the Emulator should be
clear of the damping rod by at least 1/3 the inner diameter of
the damping rod.
- During final assembly check to be sure the
adapter and Emulator are sitting properly on the top of the damping
- REMOVE STOCK COMPRESSION
VALVES OR ADJUSTERS - (Older KX80, 86 KX125 - 500, 86 YZ's etc.)
If there is any type of compression valve or adjuster, it must be
removed. Some models have Travel Control Valves (position sensitive
valves) that sit on top of the damping rod. These must be removed.
Most notably early Kawasaki's
- STOCK REBOUND ADJUSTMENT
- (ZX11) Some models have rebound adjustment. Installation of the
Emulator requires removal of the adjuster. This means you will no
longer have external adjustment. Special installation instructions
and brazing is required. The instructions are available separately
on request and are included in the ZX11 kit.
- ENLARGE THE COMPRESSION
FEED HOLES - To eliminate the harsh spike caused by the high speed
compression damping on stock forks you must enlarge and / or add compression
feed holes. Each Emulator Kit is supplied with specific instructions.
- ANTI-DIVE MECHANISMS
- Because of the addition of the feed holes at the bottom of the damping
rods any anti-dive mechanism will be disabled. This is not only allowed
it is encouraged. Because the Emulator increases low speed compression
damping (and higher spring rates are typically used) there will be
no need to create anti-dive by restricting down the flow area and
increasing high speed damping. This is beneficial because increased
high speed compression damping causes harshness on square edge bumps.
- SPRING RATE - Most
street motorcycles come with springs that are too soft. This is in
an effort to keep the front end from being too harsh with damping
rod style forks. By using the Emulator you will eliminate the major
cause of harshness. This allows you to use a stiffer spring and creates
a much better ride in every situation. Consult www.racetech.com for
- SPRING INNER DIAMETER
- The spring inner diameter must be large enough to allow for proper
flow between the inner diameter of the spring and the outer diameter
of the Emulator Valve Plate. The inner diameter of the fork spring
must be at least 4 mm larger than the Emulator Valve Plate (figure
1). The Emulator Plate outer diameter is the third dimension listed.
This is quite often a problem when using aftermarket
springs. Also check that the spring does not cover the rebound check
valve slots. If it does, most springs can be modified by grinding
a 45 degree chamfer on the ID of the spring with a carbide grinding
SPRING LENGTH / PRELOAD
- The Emulator (and adapter) length must be considered when setting
up the spring spacer length. Check to see if this is OK by measuring
Static (Race) Sag. Typical Static Sag is 25 to 35 mm (1 to 1 3/8")
for road bikes and 25% of full travel for dirt bikes.
STANDARD PRELOAD for FULL SIZE DIRT BIKES - 10 mm (3/8")
RANGE - 5 to 20 mm (1/4 to 3/4")
STANDARD PRELOAD for 4 STROKE DIRT BIKES - 15 mm (9/16")
STANDARD PRELOAD for 80cc MINI DIRT BIKES - 5 mm (1/4")
STANDARD STREET AND SPORT
TYPICAL PRELOAD RANGE for STREET FORKS - 15 to 30 mm (5/8 to
STANDARD PRELOAD - 20 mm (0.8") (using RT recommended
rate) If your model has Preload Adjustment and you are making spacers,
cut spacers to set the minimum adjustment to 15 mm (5/8").
PRELOAD EXTREMES FOR STREET FORKS - 5 to 35 mm (1/4 to 1
More Preload for heavy bikes or when using
- Static Sag is the amount the bike settles,
from fully extended, with the rider on board in riding position.
First, extend the forks completely (bike off the ground). Measure
from the wiper to the bottom of the triple clamp on conventional
forks or from the wiper to a point on the axle clamp on inverted
forks. This is L1.
- Take the bike off the stand and put the
rider on board in riding position (Street - sitting or Road race
- full tuck). Get an assistant to balance the bike or have the
rider hold onto something. Push down on the front end and let
it extend very slowly. Where it stops, measure the distance between
the wiper and the bottom of the triple clamp again. Do not bounce.
This is L2. (If there were no drag, the bike would come up a little
- Next, lift up on the front end and let it
drop very slowly. Where it stops, measure again. Do not bounce.
This is L3. The reason L2 and L3 are different is due to stiction
or drag in the seals and bushings. (If there were no drag, the
bike would drop a little further.)
- Half way between L2 and L3 is where the
Sag would be with no drag or stiction. L2 and L3 must be averaged
to find the midpoint and subtracted from L1 to calculate true
Static Sag = L1 - (L3 + L2)/2
- To adjust Static Sag use the preload adjusters,
if available, or make longer or shorter preload spacers.
- OIL LEVEL - Set the
oil level with the Emulator is installed. This way the oil level is
NOTE: Spring volume affects oil level. Aftermarket springs quite
often take up more volume than the stock springs. In fact some springs
take up so much volume the maximum oil level does not even cover
the damping rod completely when the fork is fully extended. This
causes aeration and loss of damping. Be aware of this when setting
oil level. (All oil levels recommended by Race Tech are with Race
Fork Tube id ___________
Damping Rod Cup id ___________
Damping Rod id (flat top style) __________
Spring id _________
PLEASE EMAIL US WITH FITTMENTS FOR APPLICATIONS
NOT LISTED IN OUR DATABASE.
Downloadable Cartridge Emulator Sizing and Application Chart