| This page is dedicated to 1968 ~ 1978 Honda SOHC Fours |
This page is still under construction but eventually it will contain everything we make for these
bikes as well and technical information, troubleshooting and pix of part installation and bikes.
We have 3 different regulator and rectifier options for the SOHC fours; a separate regulator
and rectifier and 2 different regulator / rectifier unit depending on how your bike is wired.
bikes as well and technical information, troubleshooting and pix of part installation and bikes.
We have 3 different regulator and rectifier options for the SOHC fours; a separate regulator
and rectifier and 2 different regulator / rectifier unit depending on how your bike is wired.
The VRREM4-SOHC for 1969~1978 SOHC Honda fours.
This unit comes with the connectors and mounting hardware to install it on
your bike. This is the easiest options for full on custom bikes that use a
minimal or custom wiring harness. There are 5 wire that connect to the
alternator side of the engine leaving only 3 to connect to the harness.
For bikes that still use the original wiring harness, see the VRREM7-H
lower on this page.
This unit comes with 2 repair harnesses to splice it into the wiring on your
bike and a packet of splicing supplies. All the terminals to populate the
plugs for the harness in case you don't need the extra length of the harness
sections.
Click here for a diagram to see how this unit would wire into your bike.
$155.00
VRREM4-SOHC
This unit comes with the connectors and mounting hardware to install it on
your bike. This is the easiest options for full on custom bikes that use a
minimal or custom wiring harness. There are 5 wire that connect to the
alternator side of the engine leaving only 3 to connect to the harness.
For bikes that still use the original wiring harness, see the VRREM7-H
lower on this page.
This unit comes with 2 repair harnesses to splice it into the wiring on your
bike and a packet of splicing supplies. All the terminals to populate the
plugs for the harness in case you don't need the extra length of the harness
sections.
Click here for a diagram to see how this unit would wire into your bike.
$155.00
VRREM4-SOHC
Charging system diagnostics for 1969 ~1978 Honda SOHC Fours.
An analog meter is preferred but digital meter is OK for these tests but you'll have to take into consideration the
static resistance in the meter. This article assumes that you have basic proficiency with an electrical multi-meter.
Start by removing the left side cover and unplug the 8 or (9 pin on some models) plug from the alternator windings
to the wiring harness. Set the meter to the lowest resistance setting, Rx1 on an analog meter or 0 to 200 ohm scale
(sometimes only labeled 200) on a digital meter. On the engine side test the resistance between the yellow wires in
all combinations. You should get .5 to 1.2 ohms resistance here. Next check from the yellow wire to ground and you
should get infinite resistance (or the same resistance as air.)
Next check the resistance from the white to the green wire. The spec here is 4 to 6 ohms but I've found that a little
out either way is OK but more than 1 ohm out is usually bad. Next test either the white or green wire to ground and
you should get infinite resistance. The green wire plugs into a ground connection but when it's not connected to the
harness it shouldn't be grounded when unplugged.
If all this checks out, move to the wiring harness side of the plug and Test the green wire to ground. You should get
no detectable resistance here or in other words: the same resistance as when touching the meter probes together. If
this is all good, plug the 8 (or 9 pin on some bikes) plug back together.
Now set the meter to DC volts and unplug the voltage regulator. Turn on the main ignition switch but set the
handlebar switch to off. Check the voltage from positive to negative across the battery then check the voltage from
the black wire that would have plugged in to the voltage regulator to ground. If there is less at the black wire than
at the battery, you have a wiring problem. This can be tested by making up a fused jumper wire to run from the
positive side of the battery to the black wire on the regulator. Then run the bike and check the voltage output.
Assuming the power to the regulator OK: plug everything back together; turn on the main switch and the handlebar
switch off. Either hand a paper clip from string or use a .002 feeler gage blade and lay it up against the end of the
alternator case (where the screws are that hold the field coil are) then pull it away. The magnetism of field coil
should bend the gage or hold the paper clip when you try pull it away. This test proves that at least the regulator is
working a little.
Now test the rectifier as per article #3 on my FAQ page.
Set the meter back to the lowest resistance setting and test the resistance from the white wire to ground. You
should get the same reading here as before when you did the test from white to green at the plug. Any discrepancy
here is a wiring problem. Unplug the rectifier and check the resistance between the yellow wire and once again you
should get the same resistance as at the alternator plug.
If this is all OK then remove the ground wire from the battery then test the resistance between the red wire where
the rectifier plugs into the positive battery cable. Then test from the red wire to the rectifier to the red wire at the
ignition switch. There should be no detectable losses here.
Since the ignition switch is unplugged, test the resistance from red to black wires in the on position. Any detectable
resistance here is bad.
If you resolve all this and you bike still doesn't charge correctly, there is one more thing to do to prove the problem
is in the voltage regulator. Start by running the bike until it is warmed up enough to idle properly. Use a fused
jumper wire and jump power from the positive side of the batter directly to the white wire that plugs into the
regulator. This will give the bike full charging all the time so do not run the engine over 1500 RPM or you risk
boiling the battery and blowing bulbs. With the engine running test the voltage output at the rectifier to ground with
the engine running at idle and 1200 RPM. If you get good charging, you need a new voltage regulator.
An analog meter is preferred but digital meter is OK for these tests but you'll have to take into consideration the
static resistance in the meter. This article assumes that you have basic proficiency with an electrical multi-meter.
Start by removing the left side cover and unplug the 8 or (9 pin on some models) plug from the alternator windings
to the wiring harness. Set the meter to the lowest resistance setting, Rx1 on an analog meter or 0 to 200 ohm scale
(sometimes only labeled 200) on a digital meter. On the engine side test the resistance between the yellow wires in
all combinations. You should get .5 to 1.2 ohms resistance here. Next check from the yellow wire to ground and you
should get infinite resistance (or the same resistance as air.)
Next check the resistance from the white to the green wire. The spec here is 4 to 6 ohms but I've found that a little
out either way is OK but more than 1 ohm out is usually bad. Next test either the white or green wire to ground and
you should get infinite resistance. The green wire plugs into a ground connection but when it's not connected to the
harness it shouldn't be grounded when unplugged.
If all this checks out, move to the wiring harness side of the plug and Test the green wire to ground. You should get
no detectable resistance here or in other words: the same resistance as when touching the meter probes together. If
this is all good, plug the 8 (or 9 pin on some bikes) plug back together.
Now set the meter to DC volts and unplug the voltage regulator. Turn on the main ignition switch but set the
handlebar switch to off. Check the voltage from positive to negative across the battery then check the voltage from
the black wire that would have plugged in to the voltage regulator to ground. If there is less at the black wire than
at the battery, you have a wiring problem. This can be tested by making up a fused jumper wire to run from the
positive side of the battery to the black wire on the regulator. Then run the bike and check the voltage output.
Assuming the power to the regulator OK: plug everything back together; turn on the main switch and the handlebar
switch off. Either hand a paper clip from string or use a .002 feeler gage blade and lay it up against the end of the
alternator case (where the screws are that hold the field coil are) then pull it away. The magnetism of field coil
should bend the gage or hold the paper clip when you try pull it away. This test proves that at least the regulator is
working a little.
Now test the rectifier as per article #3 on my FAQ page.
Set the meter back to the lowest resistance setting and test the resistance from the white wire to ground. You
should get the same reading here as before when you did the test from white to green at the plug. Any discrepancy
here is a wiring problem. Unplug the rectifier and check the resistance between the yellow wire and once again you
should get the same resistance as at the alternator plug.
If this is all OK then remove the ground wire from the battery then test the resistance between the red wire where
the rectifier plugs into the positive battery cable. Then test from the red wire to the rectifier to the red wire at the
ignition switch. There should be no detectable losses here.
Since the ignition switch is unplugged, test the resistance from red to black wires in the on position. Any detectable
resistance here is bad.
If you resolve all this and you bike still doesn't charge correctly, there is one more thing to do to prove the problem
is in the voltage regulator. Start by running the bike until it is warmed up enough to idle properly. Use a fused
jumper wire and jump power from the positive side of the batter directly to the white wire that plugs into the
regulator. This will give the bike full charging all the time so do not run the engine over 1500 RPM or you risk
boiling the battery and blowing bulbs. With the engine running test the voltage output at the rectifier to ground with
the engine running at idle and 1200 RPM. If you get good charging, you need a new voltage regulator.
| The VRREM7 |
The VRREM7 is available for several bike and except were original
wiring harness. Also all wire colors match the original parts.
This unit will require custom mounting and is ideal for custom bikes
that no longer have the original regulator and rectifier mounts but
still use the original wiring harness.
wiring harness. Also all wire colors match the original parts.
This unit will require custom mounting and is ideal for custom bikes
that no longer have the original regulator and rectifier mounts but
still use the original wiring harness.
350cc~750cc fours.
This unit requires a new plug be installed on the voltage
regulator wires on the harness. The new plug and mounting
hardware are included. The leads are 10" long giving you
plenty of options as to where to mount it.
$140.00
VRREM7-H
This unit requires a new plug be installed on the voltage
regulator wires on the harness. The new plug and mounting
hardware are included. The leads are 10" long giving you
plenty of options as to where to mount it.
$140.00
VRREM7-H
| Do not hesitate to eMail me with any questions you have about my parts sales@OregonMotorcycleParts.com |
 | |  | |  |
R255a rectifier for 1969~1978
SOHC in-line four cylinder Hondas
$48.00
R255a-H
This part has the same plug as the R255a pictured above and to
the right but with 5" wires inserted into the plug in the proper
order for Honda fours. CB350f, CB400f, CB500 four, CB550,
and CB750.
Note: the very early CB500 fours have a pin type terminals in the plug
rather than the spade type terminals like all the other Hondas used. These
pin type terminals & plug are no longer available and the best option is to
order a 6PFL plug or the RH-1h repair harness below to go with this
rectifier.
SOHC in-line four cylinder Hondas
$48.00
R255a-H
This part has the same plug as the R255a pictured above and to
the right but with 5" wires inserted into the plug in the proper
order for Honda fours. CB350f, CB400f, CB500 four, CB550,
and CB750.
Note: the very early CB500 fours have a pin type terminals in the plug
rather than the spade type terminals like all the other Hondas used. These
pin type terminals & plug are no longer available and the best option is to
order a 6PFL plug or the RH-1h repair harness below to go with this
rectifier.
Rectifier repair harness for 1969~1978 Honda Fours.
$6.00
RH-1H
This is just the ticket for SOHC Honda fours with damaged wiring harnesses where the rectifier plugs in or the
early CB500 with the obsolete pin type plug. The RH-1H repair harness comes with a mating plug for the rectifier
above and 6" of heavy duty wire color coded to your bike. Enough heat shrink tubing is included to seal the
connections after you solder it in.
$6.00
RH-1H
This is just the ticket for SOHC Honda fours with damaged wiring harnesses where the rectifier plugs in or the
early CB500 with the obsolete pin type plug. The RH-1H repair harness comes with a mating plug for the rectifier
above and 6" of heavy duty wire color coded to your bike. Enough heat shrink tubing is included to seal the
connections after you solder it in.
Adjustable Voltage regulator for
1969~1978 SOHC in-line four
cylinder Hondas.
$53.00
VR3-H
1969~1978 SOHC in-line four
cylinder Hondas.
$53.00
VR3-H
This voltage regulator ships with a
pair of 6mm Allen head screws and
you will need a 4mm Allen head
wrench (not included) to install it.
pair of 6mm Allen head screws and
you will need a 4mm Allen head
wrench (not included) to install it.
With this regulator your bike will
idle and 14.2 volts from 1500 RPM
to red line. You can adjust the for
a max output of 14.7v.
idle and 14.2 volts from 1500 RPM
to red line. You can adjust the for
a max output of 14.7v.
Adjustable Voltage regulator for 1969~1978
SOHC in-line four cylinder Hondas.
$53.00
VR3-H3p
This regulator is the same as above but it has
the 3 prong plug below installed and comes
with a mating plug for you to install on your
bike. This one is best for custom bikes or is
great to replace the old stock regulator
connections on your bike
SOHC in-line four cylinder Hondas.
$53.00
VR3-H3p
This regulator is the same as above but it has
the 3 prong plug below installed and comes
with a mating plug for you to install on your
bike. This one is best for custom bikes or is
great to replace the old stock regulator
connections on your bike
VR3-H3p regulators installed
on a CB350 four.
on a CB350 four.
This digram is for a full custom wiring
harness using the VRREM4-SOHC
harness using the VRREM4-SOHC
Do to high demand, VRREM4-SOHC and VRREM7-H may
be out of stock and take 1 to 3 weeks for us to make more.
be out of stock and take 1 to 3 weeks for us to make more.
| eMail us to check on stock on hand if you're lucky we man have one on hand... sales@OregonMotorcycleParts.com |
Do to high demand, VRREM4-SOHC and VRREM7-H may
be out of stock and take 1 to 3 weeks for us to make more.
be out of stock and take 1 to 3 weeks for us to make more.
| Do not hesitate to eMail me with any questions you have about my parts sales@OregonMotorcycleParts.com |
| eMail us to check on stock on hand if you're lucky we man have one on hand... sales@OregonMotorcycleParts.com |
| Special order only eMail us to be put on the list for one |
| Special order only eMail us to be put on the list for one |