Tuning 1995-2007 Harley kits(except Gen3 kits)
1250ST.pdf
Green LED pot(1st):
Air fuel mixture screw adjustment. With TFI installed
and the bike fully warmed up, screwdriver in hand, locate the green LED and the
pot right below it. Using the throttle raise the RPM to a high idle or about 2000-
RPM. Once there, slowly turn the green pot clockwise from the 1:00 position (off)
until you achieve the highest RPM and smoothest running sound (like a mixture
screw on a carburetor). You should find the best setting between 2:30 and 4:00
o’clock. If you turn the green pot clockwise and the engine does not accept any
more fuel (RPMs drop when adding fuel) you may have one or more of these
problems (See troubleshooting Motorcycle).
Yellow LED pot(2nd):
Acceleration fuel adjustment. Anytime the LED is on,
this pot is adding fuel. In neutral raise the RPM slowly up through the mid range
and see no yellow LED. However, opening the throttle quickly from idle you
“should” see the yellow LED come on. Add one clock position at a time until the
bike says too much (hesitation) then back off 2 clock positions, if adding makes it
worse go opposite direction. The yellow pot adds most of its fuel below 75% of
maximum RPM. If no yellow LED there is not enough load to turn it on. At that
point the street or dyno will be able to show the difference.
In a lot of cases the yellow pot can be turned to a lower setting and also completely off if your MPG takes a hit too badly with little or no noticable differences.
Red LED pot(3rd):
Main jet fuel adjustment. It adds about 5 points of
main jet fuel with every clock position. For example, one clock position is the same
as 150 to 155 main jets. Fine tuning: Start with the suggested setting and then add
one clock position at a time until the bike says too much (hesitation) then back off 1
clock position, if adding makes it worse go opposite direction. The red pot adds
most of its fuel above 70% of maximum RPM.
RPM pot(4th):
1: Sets RPM that the red LED pot (main jet fuel #3) turns
on. All Harley. One clock position is roughly 1000 RPM. This pot should be set to
about 70% of redline. (For example: Harley Softail redlines at 5600 rpm and 4000
is roughly 70% of redline which would be 4:00 o’clock). Verify setting by raising
the RPM in neutral, look for green and yellow LEDs to shut off and the red to turn
on at the chosen RPM or refer to suggested settings if you have no tachometer.
2: Shuts off idle fuel. In some cases modified engines
can produce a richer than normal idle mixture. 1:00 o’clock through 6:00 o’clock
sets RPM that the red LED pot (main jet fuel) turns on. When the 4th pot is turned
to 7:00 o’clock the software is instructed not to add fuel until 1250 RPM. Also,
when setting the 4th pot at 7:00 o’clock the software automatically defaults to 4000
RPM (internally) to switch to the red LED pot (main jet fuel).
Here's the suggested settings for the TFI from Techlusion.
1250ST.pdf
Green LED pot(1st):
Air fuel mixture screw adjustment. With TFI installed
and the bike fully warmed up, screwdriver in hand, locate the green LED and the
pot right below it. Using the throttle raise the RPM to a high idle or about 2000-
RPM. Once there, slowly turn the green pot clockwise from the 1:00 position (off)
until you achieve the highest RPM and smoothest running sound (like a mixture
screw on a carburetor). You should find the best setting between 2:30 and 4:00
o’clock. If you turn the green pot clockwise and the engine does not accept any
more fuel (RPMs drop when adding fuel) you may have one or more of these
problems (See troubleshooting Motorcycle).
Yellow LED pot(2nd):
Acceleration fuel adjustment. Anytime the LED is on,
this pot is adding fuel. In neutral raise the RPM slowly up through the mid range
and see no yellow LED. However, opening the throttle quickly from idle you
“should” see the yellow LED come on. Add one clock position at a time until the
bike says too much (hesitation) then back off 2 clock positions, if adding makes it
worse go opposite direction. The yellow pot adds most of its fuel below 75% of
maximum RPM. If no yellow LED there is not enough load to turn it on. At that
point the street or dyno will be able to show the difference.
In a lot of cases the yellow pot can be turned to a lower setting and also completely off if your MPG takes a hit too badly with little or no noticable differences.
Red LED pot(3rd):
Main jet fuel adjustment. It adds about 5 points of
main jet fuel with every clock position. For example, one clock position is the same
as 150 to 155 main jets. Fine tuning: Start with the suggested setting and then add
one clock position at a time until the bike says too much (hesitation) then back off 1
clock position, if adding makes it worse go opposite direction. The red pot adds
most of its fuel above 70% of maximum RPM.
RPM pot(4th):
1: Sets RPM that the red LED pot (main jet fuel #3) turns
on. All Harley. One clock position is roughly 1000 RPM. This pot should be set to
about 70% of redline. (For example: Harley Softail redlines at 5600 rpm and 4000
is roughly 70% of redline which would be 4:00 o’clock). Verify setting by raising
the RPM in neutral, look for green and yellow LEDs to shut off and the red to turn
on at the chosen RPM or refer to suggested settings if you have no tachometer.
2: Shuts off idle fuel. In some cases modified engines
can produce a richer than normal idle mixture. 1:00 o’clock through 6:00 o’clock
sets RPM that the red LED pot (main jet fuel) turns on. When the 4th pot is turned
to 7:00 o’clock the software is instructed not to add fuel until 1250 RPM. Also,
when setting the 4th pot at 7:00 o’clock the software automatically defaults to 4000
RPM (internally) to switch to the red LED pot (main jet fuel).
Here's the suggested settings for the TFI from Techlusion.
