JIMS Twin Cam 120, 131, 135 - Manual (Page 6)

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Before Installing Engine In Chassis preparation
If a shop has performed the install and start up of your new engine then you
will not need to perform the following steps. But you will need to know if they
have indeed done the following steps. If you will be doing the installation of
JIMS engine, then you will need to do the steps listed below.
S Sp prro occk ke ett S Sh ha afftt S Sp pa acce err IIn nffo orrm ma attiio on n
If your motor assembly came with a sprocket spacer installed already you
should be ready to install engine in chassis from the info you gave the Sales
Dept. If you have an extra spacer shipped with the engine then check appli-
cation list below for correct usage per year/model.
S
Sp prro occk ke ett S Sh ha afftt S Sp pa acce err
• Inspect the engine sprocket shaft, seal and bearing cavities for any packag-
ing debris before continuing.
• Locate spacer specific to your application:
• For 1999 to 2005 Dyna "A" use H-D 24038-99A, JIMS No.1286-1319, spacer,
.888” long.
• For 2006 to present Dyna "A" use H-D 24008-99A, JIMS No.1286-1320,
spacer, 1.0950" long.
• For 1999 to present FL "A" use H-D 24008-99A, JIMS No.1286-1320, spacer,
1.0950" long.
• For 2000 only Softail "B" use H-D 24038-99A, JIMS No.1286-1319, spacer,
.888" long.
• For 2001 to - 2006 Softail "B" use H-D 24039-01A, JIMS No.1486-1834,
spacer, .988" long.
• For 2007 to - present Softail "B" use H-D 24008-99A, JIMS No.1286-1320,
spacer, 1.0950" long.
• Inspect spacer for nicks and dents.
• Lightly coat outside diameter of sprocket shaft spacer and the inside of the
sprocket shaft seal with clean 20w-50 H-D ® motor oil.
• Slide sprocket shaft spacer onto sprocket shaft, until it is seated on the
sprocket shaft bearing.
Recommended Oil Cooler:
These engines need to be fitted with an effective oil cooler. JIMS recommends
you use the current H-D Accessories Book Oil Coolers. Order your cooler kit for
the correct year and model of the motorcycle. Besides the 1st priority of an oil
cooler you can also add a JIMS “Forceflow Cylinder Head Cooler” P/N. 5400
for added cooling. See JIMS catalog or website.
Battery :
It is very important to always use a well maintained battery with performance
engines. Always keep a full charge on the battery or you will cause damage to
the starter drive system. JIMS recommends usage of the H-D OEM maintenance
dramatic. As a rule-of-thumb, you can expect a pressure loss of 3% for each
1,000 feet of altitude gain, meaning that at 10,000 feet elevation an engine will
lose almost 30% of its power. This loss in power will be slightly greater due to
the air/fuel mixture becoming richer.
Carburetor settings can become too rich for smooth operation and/or maxi-
mum power production. If you are going to operate your JIMS engine above
3,000 foot elevation, you may find it necessary to alter the jetting. Denver for
example is one mile above sea level; so you may need to install the next leaner
needle, slow jet, and possibly a couple sizes leaner on the main jet. (A highly
experienced engine tuner should make such changes.) Atmospheric conditions
are much more important when racing, because small differences can deter-
mine whether you go on to the next round or go onto the trailer. Races are
often won or lost on a tuner's ability to dial in the jetting as the atmospheric
conditions change during the day. If you do not understand jetting, do not
hesitate to ask questions. The majority of race tuners are more than willing to
share much of what they know, but do not expect to get all the details - it is
racing after all! Drag Racers are a congenial group and they want you to be
there, racing with them, and enjoying it, but it is in your best interest to gather
multiple tuners’ suggestions to help ensure the jetting set up you choose is fit-
ting for the conditions.
More Power- Air Flow Volume:
Ultimately, the amounts of power your JIMS 120, 131, & 135 Race engine can
produce is determined by two factors. How much air it can process in a given
time and how efficiently it uses that air to supply useful power to its crankshaft.
The JIMS 120 Race engine delivers about 121 horsepower while the 131 puts
out about 130 horsepower. The 135 delivers about 136 horsepower. It is very
possible to increase that output by 20% or more, and it’s also possible to re-
duce output by a similar percentage. Each and every part of this engine is per-
fectly balanced, designed and developed or selected to work together for
maximum airflow and power output. Keep in mind it is easier to lose power
than to gain power. For instance, if you upgrade to a larger air cleaner or car-
buretor to flow more air, the result may not meet your expectations. That’s be-
cause a larger carburetor does little to improve power if the total airflow is
limited in some other part of the engine.
Substantial power gains require substantial modifications. Increased airflow
through the cylinder heads of your JIMS 120, 131, & 135 Race engine requires
the manifold and both intake and exhaust ports be carefully and skillfully mod-
ified. Cylinder head porting continues to be an art form and should only be per-
formed by a practiced porting expert. While the Screamin' Eagle air cleaner
element is one of the highest flowing units available, the stock airflow is sub-
stantially increased with larger filters that allow more air volume than the sup-
plied filter. However, they may interfere with riding comfort depending on
make, model and personal preferences.