V4 Spark

All New OEM Replacement Spark Igniter Module for  1980's Honda VF Magna/Sabre/Interceptor

 How-to: adapting later model Pulse Generators

AL box version

Complete unit in a new aluminum enclosure (OEM small box for size comparison)

These are all new modern microprocessor controlled replacements for the failing 25-30 year old OEM spark modules in Honda 1980's V4's.  I had replaced one of my failed originals with a used one off E-bay, and a year later that failed :-(.  This looked like a fun project and ignition control is not new for me having previously developed MegaSpark for MegaSquirt.  The main goal here is a reliable OEM stock replacement made of all new electronics, including a new wire harness and new connector, but I have added a couple of extra features - user adjustable timing and a coil-on-plug (COP) option.

Available for -

  • Magna/Sabre: 82-86 V45, V65, V30, and 700
  • Interceptor: 84 VF1000F, 85-86 VF1000R, 83-84 VF750F, 84-85 VF700F, 84-86 VF500F, 83-85 VF400F

These are just slightly smaller than the original so fits with out any modifications to the module holder.  You will probably want to add some padding or a velcro strap.

I started this Sept '12 and have ridden over 20,000 miles.

Review with video

Project thread on v4musclebike.com forums (skip to the later pages if you just want to get to users feedback)


 USB Interface (requires windows)

Some features -

Oct '17 - have had water get into some AL boxes.  They are now being "potted" which is filling them with epoxy.  People can send in their unpotted boxes and if they would like to have this done.

How much more Power/MPG will I get with this?

A old ignition system can cause a loss of both power and gas mileage if is it no longer operating properly, so you may get a restoration of power/MPG.  It just depends on the condition of what you currently have.  Note though there is not a reason to expect any power or gas mileage gains over a properly operating OEM module.  Creating more power is done by moving more fuel and air into the cylinder, and the ignition system just simply does not affect that.  You have to change carbs/jetting, intake, cams, exhaust, etc to get a real increase.

<= Verification of advance curve

Pink is the V4 Spark and blue an OEM V45 module.

I have been testing OEM modules to verify the timing parameters.  Even if your module seems to running OK, if might be starting to fail.  This OEM module is starting to get erratic at higher RPM's.


  1. Unplug/remove your old module(s).  Note there is a latch on the connector - depress to release.
  2. Check that the connector on the bike harness is good condition, terminals are clean, and none are pushed back or loose.  You can get new connectors from corsa-technic.comcycleterminal.com (Locking Type .110) or vintageconnections.com (part HP6L Latching Set White Nylon).
  3. Install and plug in the new module(s). 

Ride & enjoy.

For COP, follow the wiring diagrams here.


One of the spark modules also connects to the tachometer (the other one the fuel pump cut off ).  An erratic tach is a pretty good indication that you have a bad module (though not conclusive, could be a tach problem, and you could still have a module problem and get a good steady tach).  Swap the two spark boxes to see if the problem follows the box.  Easiest is to try a good known spark box (though if you had one you probably wouldn't be here).  Check the connector for loose, bent, or dirty pins.

There are two LED's (on the OEM box version, the box end needs to be removed to see these).  One LED will flash steadily (early OEM box firmware versions do not do this).  This will let you know that the module has 12V power and is a live.  Starting with firmware version "e", this LED will quickly flicker if, when the engine is not running, the pulse generator output looks off.  Follow up by checking the pulse generator with a meter.  (What is the different between flash and flicker here?  Flash is slow enough to count the blinks, 1... 2... 3... Flicker is way too fast to count them)

The other LED will blink as it sparks.  This will let you know that it is getting trigger pulses from the pulse generators.  If you are not seeing this, then there is a problem with the pulse generators or wiring to them.  If you are seeing this, then there is a problem with the coils, wiring to coils, plugs wires, spark plugs.

Pulse generators and ignition coils are also starting to fail.  If you are having trouble after installing the new modules, then one of these is a likely cause.  Use a meter to check the pulse generators.  The ignition coils can be swapped to see if a problem follows.

Wire Color Function
Black +12V
Green Ground
Blue Pulse generator +
White Pulse generator - (tied to ground)
Yellow Ignition Coil
Red COP 2nd Ignition Coil (may be present even if individual COP option not installed)


The rev-limiter cuts the ignition if the engine RPM gets too high.  This is only done on the front bank, cyclinders 2 & 4 - which is the OEM big box w/ red plug.  The other small box w/ white does not contain a rev-limter.  On my modules, the rev-limiter can be set to either enabled or disabled.  The RPM that it kicks in at can also be set.  I default it to 500 RPM above the start of the tach red-zone.

The factory rev-limiter was not added until later in '83, but it can be enabled on earlier models as an upgrade.


Tach Red-Zone


V45/V65 Magna/Sabre 10,000 RPM 10,500 RPM
700 Magna/Sabre/Interceptor 10,500 RPM

11,000 RPM

V30 Magna 11,500 RPM 12,000 RPM 
VF750F Interceptor 10,500 RPM 11,000 RPM
VF500F 84-85 Interceptor 12,000 RPM 12,500 RPM
VF500F 86 Interceptor 11,500 RPM 12,000 RPM
VF1000F 84 Interceptor 10,500 RPM 11,000 RPM
VF1000R 85-86 Interceptor 11,000 RPM 11,500 RPM
VF400F Interceptor 12,500 RPM 13,000 RPM


Domestic shipping is by USPS Priority mail.  International shipping is on E-bay purchases (E-bay id dualcam - https://www.ebay.com/sch/dualcam/m.html - contact me if you don't see your year/model listed).

Contact - te27s5@yahoo.com

Payment via PayPal.  ** Please make sure your PayPal address is correct!!! **   E-check payments take a few days to go through.

Lead time: I try to keep assembled V45/V65/700 AL box version on hand, but I don't do the settings programming and final test until ordered, so may be a day delay before shipping.  Other models and Individual COP are built on order, so these will have a few more days delay as I assemble them.

AL Box Version - Stock Replacement & Series COP

Qty 1: $84.50
Qty 2: $159.50

Q: My 84-85 700 Sabre only has one box - what do I order???

A: Your Sabre has two boxes - the second (big box w/ red plug) is under the voltage regulator.


** 85-86 700 Magna w/ single box **

This is two AL boxes plus an adaptor cable to connect in to the bike harness.  Note the orignal mounting bracket is designed for the original box.  You will need to secure these in place with say zip-tie or velco strap.

Qty 2 AL boxes + cable: $169.50

** 85-86 VF1000R Interceptor w/ single box **

This is two AL boxes plus an adaptor cable to connect in to the bike harness.  These will slip inside the rubber mounting sleeve, but you may need to secure them in place with say zip-tie or velco strap.

Qty 2 AL boxes + cable: $169.50

AL Box Version - ** Individual COP **

Check out the COP page before ordering

Still works for stock replacement and series COP, these just have an addition coil output.

These will be shipped with the configuration set for stock.  Update the settings when running Individual COP.

Qty 1: $94.50
Qty 2: $174.50

Individual COP spark module break-out cable, shown on the COP page Individual diagram - *not* required, but helps make the wiring easier by not having to hack on the factory harness.

$15 for a pair


Returns for full refund of purchase price excluding shipping accepted within 30 days of purchase.  You will have to pay for the return shipping.  No refunds or refund will be minus a repair charge for units that have been abused.

Hafner Enterprises LLC warrants products to be free from defects in material and workmanship under normal use and if properly installed for a period of one year from date of purchase.  This shall constitute the sole remedy of the purchaser and the sole liability of Hafner Enterprises LLC to the extent permitted by law, the foregoing is exclusive and in lieu of all other warranties or representations whether expressed or implied, including any implied warranty of merchantability or fitness.  In no event shall Hafner Enterprises LLC be liable for special or consequential damages.

Electronics can fail without any warning at any time.  This is true for any product and vehicle.  Ride smart!

OEM box version DIP switch settings

These may change with firmware version, shown is latest.  After changing, the module must be power cycled before they take affect.

DIP switch settings 

^ = ON, v = OFF
Switches 1-5 = Model ^vvvv 82-83 V45 Magna/Sabre

83-86 V65 Magna/Sabre

^^vvv 84-86 700 Magna/Sabre, 84-85 VF700F Interceptor
vv^vv 84-85 V30 Magna
^v^vv 83-84 VF750F Interceptor
v^^vv 84 VF1000F Interceptor
^^^vv 84-85 VF500F Interceptor
vvv^v 86 VF500F Interceptor
^vv^v 83-85 VF400F Interceptor
^^v^v 85-86 VF1000R Interceptor
vvvvv Custom, set by configuration program 
Switch 6 = Rev-Limiter Enable ^ Enabled
v Disabled

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