Topic: Ignition Upgrade using GM HEI Modules

[Pinhead]

Just trying to find cheap alternatives to the often overpriced stock parts for our bikes.
Main page: http://home.comcast.net/~loudgpz/GPZweb/index.html#home


http://home.comcast.net/~loudgpz/GPZweb/Ignition/CBheiModCavCoil.html

This project is an ignition module design to replace the stock unit for a 1980 Honda CB 750 C motorcycle using aftermarket GM ignition coils commonly found on Chevy Cavaliers and many other GM cars instead of the stock coils. It also uses two GM HEI igniter modules. The parts for this project should not cost much more than $35, (not including the coils which are about $20 each). This module is designed to work with the stock inductive pickups. This project will also work as a replacement for the many other early 1980's Honda CB motorcycles that use the same pickups, rotor, as the 1980 CB 750 C. It uses a mechanical advancer unit. This project is not compatible with electronic-advance type ignitions.

http://home.comcast.net/~loudgpz/GPZweb/Ignition/GPZheiModForPoints.html

This project is to adapt a General Motors High Energy Ignition (HEI) module to provide spark for any Kawasaki KZ motorcycle originally equipped with points. It can also be used on any vehicle incorporating a 12-volt, negative-ground electrical system using a standard Kettering-style ignition system.

The purpose of this project is to use the HEI module in order to reduce wear on the points. It also eliminates the need for the condenser and will allow the use of lower resistance ignition coils in order to get a higher-energy spark at the plugs. It will also allow the elimination of any ballast resistor as long as the ignition coil's primary resistance is 2.4 ohms or higher.

EDIT: The above links no longer work. Find the website HERE.

EDIT: I have had a very hard time finding 4-pin HEI modules at junk yards so I chose to use 7-pin HEI modules instead. To use the 7-pin modules, however, the wiring has to be slightly altered. Note: The attached diagram is for the '79-'82 CB650 and other TCI-equipped Hondas from the '80s using 7-pin modules.

EDIT: During the install process of this ignition I contacted the author of the mod for suggestions. Here is what he had to say:

The 4-pin has internal dwell compensation.
The 7-pin has no internal dwell compensation circuit. The 7-pin is just a two-mode driver.
B stands for bypass. You are using it in bypass mode when B, R, and E are unconnected.
R stands for reference. That is the signal from the module to the car's ECM. It can be used for a tach signal, which is how some people probably use it, but that is not the real purpose of R. The ECM uses the reference signal to determine dwell and timing. That ECM signal then returns to the module through pin E. E stands for ECM.
 
N on the 7-pin correlates to W on the 4-pin.
P on the 7-pin correlates to G on the 4-pin.
 
N and W are what I refer to as the negative side of the reluctor pickup (positive and negative are arbitrary labels, but I use them consistently, which is what matters, other sources may refer to them opposite from what i do).  The main difference between the 4-pin and 7-pin is that the bias voltage on N is relatively steady, while the voltage on W changes greatly with RPM (based on reluctor signal strength and output's current limiter usage). (My full notes on the 4-pin are available from that link you referenced.)
 
If you are using Cavalier coils, (as that is what the link refers to, note there is a different page for using stock spark coils), then the W-pin does not get used, so the issue between W and N is irrelevant.

However, P and G also have a slight difference in their behavior. The thresholds are slightly higher on the 7-pin module.  So there may need to be a slight compensation on the negative terminal of the pickups. The difference is about 1 volt. A 1-volt reference voltage should be applied to the negative sides of the reluctor pickups.  That is the blue wire with white band, and yellow wire with white band.  On the 4-pin page, those wires are just tied to ground. To use it with the 7-pin module, you will likely have to go with a simple voltage provider like that used on the Kawasaki version:
http://home.comcast.net/~loudgpz/GPZweb/Ignition/GPZgmHEImod.html

Use P in place of G. The white band wires would be the negative pickup wires, but try both polarities in case the timing seems off. This is in case someone swapped the white bands. Double check the timing with a strobe to make sure the polarity is correct (wrong polarity alters the timing).

If the polarity seems reversed, maybe there is a chance someone put the white band on the wrong wire.

[Duke McDukiedook]

Looks pretty interesting, and saves $$$.

[Pinhead]

Bump for those who are interested.

[fmctm1sw]

Hmmm, yes.  I've been wondering about weak spark.  Another idea to add to the "consideration shelf."

[MJL]

I've seen that, and pm'd Hondaman about it. His thought was basically Radio Shack parts aren't very good. I couldn't find exactly what I needed at my local RS anyway, so I haven't gotten very far with it.

[Soos]

Conclusion:
Each of these circuits were assembled and hooked up to a test rig to simulate an engine.  Each performed very well.  None were actually installed onto a motorcycle yet.

Hrmm.....I'll be the first to wait until some one else actually does this mod, and shows how to mount it under the tank......
I'm all for one of a kind mods, and being the first to try stuff...
But after frying $$400+ I'm a bit burned on replacing the stock ignition......
Not even sure I want to contact dyna to see if they will replace the ignition module.
It was DEFINATELY fun.
I really liked being able to program my own advance curves.....
No idea why it fried, and right now don't really care.
( I swear that missing advance the dyna gives beyond what the stock setup has affected my power, might mod a stock advance unit to get it back one day.....)






I'm just glad the motorcycle accident I saw wasn't me today.(this week has been good for work, but the trips home have sucked in general)

Damned SUV's.
Oh wait... it's not the SUV's, it's the f^%$#ng bad drivers.

Guy was in BAD condition too.
But his bike took the brunt of it I think.
The front end separated from the frame.
His arm looked like it was coming out his back, not his shoulder....
At least he had armored jacket and pants as well as wearing his helmet.
I think if I hadn't stopped he might have wandered into traffic.

He kept trying to get up to look at his bike.
when I saw the blood dripping from the back of his coat I almost puked.
Thats about the time the cop showed up.
I gave my statement, and waited with him for the ambulance.(helped the cop keep the guy still by talking to him mainly)





Well, I'm being told I need to sleep now so I can get up at 4:00am......
l8r all.

[dusterdude]

damnit jim,the geocities page is longer available,does anyone have this they could send me.im really interested in it.pm me if you have it.thanks

[Alan F.]

yeah, they closed geocities a while back... I wonder if the info was mirrored anywhere too.
-Alan

[DavePhipps]

You might try looking here
http://polymer52.webs.com/motorcyclediysinfo.htm
I think there's something about HEI units there

NVM he linked to the same geocities pages

This looks interesting though
http://xs650temp.proboards.com/index.cgi?board=ID&action=print&thread=7899

[Alan F.]

Here's another:  http://webpages.charter.net/n8nxf/HEI-CX650C.pdf

[TomC]

Hi Pinhead et al
     The link that Alan F. posted should work for the electronic ignition CB650s and the twin cam fours.
     As for running one of these modules with a set of points. I am nor sure what input the module is looking for. Does anyone know?
     One of the links that I found searching Google for "Motorola MC3334" suggested using a relay to supply current to the module. This sounds like a good idea as there will be a high current of short duration.
     TomC in Ohio

[Pinhead]

I remember reading through these a long time ago and if I recall correctly, in order to use these modules with points, a diode and a specific value of resister had to go somewhere. I don't remember how it was wired up, however.

Personally if I had a point-ignition system I'd run Hondaman's ignition system.

[mark]

was thinking about something of the sort... some time back... found this page...

http://www.mynode.com/2wheel/?t=simple.html&v=hei/index.html

I don't like points for a number of reasons, but I own a lot of old motorcycles so I have a lot of points. I'm experimenting with the 7-pin GM HEI module as a drop-in points triggered alternative. I have successfully run a 1965 Ducati 250 and a 1975 Honda CB400F using HEI modules.

The 7-pin module was used on many GM cars and trucks in the 80's and 90's. I order a module for a 1985 Chevrolet El Camino with a 5L V8 and 4bbl carb because I like El Caminos.

I would have called it a '75 and used the 4-pin module at around half the price of the 7-pin.


ended up getting a dyna in a box lot of parts. it works.

[TomC]

Hi Pinhead
     I agree.

Personally if I had a point-ignition system I'd run Hondaman's ignition system.

     I am asking to increase my knowledge of how electronic ignition works.
          TomC in Ohio

[Pinhead]

BTT

Edited original post with updated links!!!!

[cb650]

There is a thread on this at the 750/9oo dual cam site.  Same iggy as out 650's.   

[Pinhead]

Back to the top!

I found a working link. The site describes using GM HEI modules with stock coils and GM low-resistance cols. Conversion for many different bikes, including points-fired systems...

http://home.comcast.net/~loudgpz/GPZweb/index.html#home

[Pinhead]

While investigating the use of GM HEI modules, I came across this article. It describes the advantages of different HEI modules combined with different coils.

http://www.corvetteforum.net/c4/doctorj/heicoilinfo.htm


I thought you Dyna lovers would be especially interested in this little snippet, though...

Some time ago I ran across a web page for DUI ignitions & their 'Dyna' Ignition modules. Whoever wrote that ad copy has NO electrical training whatsoever. Their 'performance' claims are such erroneous crap I would put them dead last on a list of people to ever buy from.

[TwoTired]

I thought you Dyna lovers would be especially interested in this little snippet, though...

Some time ago I ran across a web page for DUI ignitions & their 'Dyna' Ignition modules. Whoever wrote that ad copy has NO electrical training whatsoever. Their 'performance' claims are such erroneous crap I would put them dead last on a list of people to ever buy from.

Now you've done it.  Telling people their God doesn't exist will get you a lot of hate mail, if not your throat slit.

I mean i must be good.  It says electronic right in the "technical specifications"!
http://www.dynaonline.com/skins/products/sportbikes/dyna_s/

When I read it, I wondered what happened to the "technical" content.  Like where was it?  Can anybody else see anything technical in what they listed?

"Technical Specifications" would be a list of parameters, such as it's input voltage acceptable range, its output trigger repeatability/tolerance, its guaranteed operating temperature range, its DWELL parameters, it's output load current parameters/tolerance, etc.

Marketing is more important than verifiable facts in some companies.

Cheers,

[Duke McDukiedook]

The technical content is in the memory hole, they know that the s is 30+ year old technology but it still brings  in a few bucks every now and then.
Is a retool and  technology upgrade really worth it to them? Probably not.

[Pinhead]

As of today I am running GM coils and 7-pin HEI modules on my '79 CB650 (couldn't find the 4-pin modules at the junk yard).

The idle is absolutely amazing. The bike starts up extremely easily. Very little choke is needed (impressively so, considering the generally "cold blooded" nature of the CB650). The bike can take off in 1st gear at idle without dying. The low-end (1000 to 2500 rpm) is as smooth as my CM400 that has CV carbs.

I'm running Iridium plugs which are gapped at 0.060 inches. As of right now, I'm not using any resistors in the plug boots (the resistor plugs are ~5k ohms each).

With my highly modified engine at 10.7:1 compression ratio, there is no detectable ping even going up a steep hill at 35mph in 5th gear.. Even if I go to WOT. (This is more-than-likely a function of my engine configuration more than the ignition.)

With the stock ignition I would have definitely been forced to down-shift as the engine would bog down otherwise (verified by a ride with the stock ignition earlier today).

I'd say this is definitely worth a try, especially since a pair of HEI modules and coils cost me less than $30 at a salvage yard. 

[turboguzzi]

hei pin

glad its working for you, another cheap option is simply using ignition modules, coils and pickups from 80's-90's in line four bikes, say GPZ's, GSXR's, ZXR's , etc.

that's what i am using in both of my racers,

TG

[Pinhead]

Interesting. What is involved when converting from, say, points to the ignition you're using?

For all of you points guys who would like to upgrade your ignition and use virtually any coils that you can physically mount to your bike, take a look HERE:

A points ignition wastes most of the current it consumes at low rpm because the dwell time controlled by crank angle, not by the amount of time it takes to charge the coil which is essentially constant regardless of rpm. The excess power is wasted heating up the coil. The GM HEI controls the dwell time by measuring how long it took the coil to saturate on the previous cycle. If the coil did not reach saturation, the HEI turns the current on a little sooner, if it reached saturation too soon, the HEI delays a little longer for the next cycle. This is a big advantage for older motorcycles which often have marginal alternator output, since at low rpm when the alternator is putting out little current, the HEI controlled ignition uses much less than a conventional points ignition.

[turboguzzi]

Interesting. What is involved when converting from, say, points to the ignition you're using?

For all of you points guys who would like to upgrade your ignition and use virtually any coils that you can physically mount to your bike, take a look HERE:

A points ignition wastes most of the current it consumes at low rpm because the dwell time controlled by crank angle, not by the amount of time it takes to charge the coil which is essentially constant regardless of rpm. The excess power is wasted heating up the coil. The GM HEI controls the dwell time by measuring how long it took the coil to saturate on the previous cycle. If the coil did not reach saturation, the HEI turns the current on a little sooner, if it reached saturation too soon, the HEI delays a little longer for the next cycle. This is a big advantage for older motorcycles which often have marginal alternator output, since at low rpm when the alternator is putting out little current, the HEI controlled ignition uses much less than a conventional points ignition.

my recomendation is to pick a 90's gsxr ign box, coils, pick up and ign. rotor.
the rotor bolts on instead of the stock advancer. the pick up can be mounted with two M5 screws to the stock honda plate. complex bit is wiring the box following a GSXR wiring diagram.

the mechanics part is  here
http://forums.sohc4.net/index.php?topic=18579.msg194169#msg194169

so just add the DIY harness

the beauty of it is that its a one pickup system, after setting it, haven't touched it in four racing seasons.... best run it with resistance caps AND plugs.
also no need to break your head over dwell angles or whatever, very low power consumption too,
i run total loss and often a 4 A/h battery lasts the whole race weekend = four 20 min sessions + 25 min race

[Pinhead]

I never can leave well enough alone so I'm still trying to reinvent the wheel.

When GM introduced the HEI, plug gaps were originally set at 0.080" at the factory. This was later turned back to 0.060" because the distributors and wires weren't lasting long enough. We don't have a distributor to arc over or wires overlapping to cause cross-talk which are the two of the HEI's problems. The GM DIS ignitions (where we get the Cav coils) are factory-gapped at 0.060 inches so the plugs can last 100,000 miles. By the time they're changed I've seen the gaps as wide as 0.100 inches and still firing.

Right now I'm running at .060" with no problems, and going to open it up to .065" today to see how it runs. I'll widen the gap by .005" until I get a miss or lose power at WOT, and then back it down to the last best setting. There was a study by a prominent ignition company that said 0.100" is the optimum plug gap for kernel expansion if enough spark energy is available. I probably won't be able to get quite that far, but the closer the better.

Also note that if I can easily go to 0.060" on my bike, most people should be able to go a lot further; high compression and lean mixtures are more difficult to fire than low(er) CR and stoich mixtures. I'm running 11:1 CR and trying to maintain lean cruise which makes it much more difficult to fire the plugs than the factory 9:1 CR.