750 twin and Mallory Hyfire - moved from 'Coil recommendation for '79 750 twin'

If you have the 440 pickup then you need either the 440 or the 82-83 750 twin timing advancer. There are other options but using the points timing advancer is not one of them. You need the igniter as well, but you can use one off a four cylinder by just using one side of it.

I have no idea what will work with the Mallory, I don't know if you need the igniter or not.

Post edited by: steell, at: 2006/08/14 18:19

so as not to be a thread hijacker, I made a new one...

I downloaded the HiFire manual today, and it looks like I do not need the 440 igniter. I can just use the magnet and crankshaft lode to trigger the Mallory unit (purple and green wires).

Steell, are you saying that I can't just put the 440 lobe on my '78 750 advancer? I do (or did, need to check) have the 440 advancer, but it was really rusty, springs shot...

Getting this done will be a great advanture. Then to continue with the fuel injection, then ignition control, woo hoo!

From the archives:

I used the advance weights and springs from the 750 timing advancer on the 440 advancer, as I wanted to keep the stock 750 timing curve.

Since I have everything except the weights and springs from the 440, it looks like I'm in business!

securitygeek wrote:

From the archives:

I used the advance weights and springs from the 750 timing advancer on the 440 advancer, as I wanted to keep the stock 750 timing curve.

Since I have everything except the weights and springs from the 440, it looks like I'm in business!

You answered your own question

You can also use the slug off a 650 or 750, but you have to press it off the shaft and flip it over, then press it on the 750 twin shaft, Lou did the research

Sometimes I talk to myself/think out loud, to help me work through an issue. Sometimes I do it just because! Hopefully it will help someone else out a little.

Now, a couple of days of rain, so I can make the switch without interupting the riding. I'd normally just do it in the late night/wee early morning hours, but I need to get some running time in. Getting ready to run another marathon Oct 1. I do not know why I decided to do that!!!

I recall us working on this idea at some point, but can't remember the final resolution. (Too much fluoride in the water... yeah that's it). It would be great to hear what you find out Security, and if you could maybe do a quick write up.

So is the Mallory just an ignitor? Or what? If you have the pickups and rotor why can't you use a KZ ignitor? Just curious...

Also, you can make an ignitor for about $15 or $20 for your bike.

Post edited by: loudhvx, at: 2006/08/15 13:01

The Mallory Hifire VI-aL is basically a Mallory version of the MSD 6a-l. Basic digital multi-strike ignition amplifier with built-in adjustable rev limiter for engine protection. But I don't know if the rev limiter will be usefull, it's got settings for 4,6 or 8 cylinder engine, but not for a twin.

I do not have a KZ ignitor, but I do have the Mallory setup that has been sitting in my garage for more than a year, might as well make use of it. It was removed from my Jeep Grand Wagoneer (along with my megasquirt system) before it went to the junkyard

With the Mallory, I don't need to build an ignitor.

So it's a MSD. That means it's CDI.
I assume the mallory was meant to use the stock coil for a car. I'm not sure that a motorcycle coil is a great match for CDI. The CDI just uses a coil as a step-up transformer, but motorcycle coils are "slow" and tend to reject spikes more so than a "fast" car coil would. It'll probably work, but my guess is that a 1 or 2 ohm coil may be better.

MSD usually drops the multiple sparks at higher RPMs (from what I've read). If you get some sputter, you may want to try a different coil.

Good luck, I am always for using what you got!

I've always got the Ford TFI coil that I used with the Mallory thing. However, it does not have the dual output, like I need for the twin. Any ideas on how I might overcome that? I'd rather not need to buy a lower ohm dual output coil. When I put my HD coil on, I used some of the plug wires I had from the Jeep. These are spiral wound, not copper core wires. Do you suppose that I might want to get some new copper core plug wire, and make up some new ones(longer than original because of the new coil location), using my NGK caps? Then I could build the ignitor you (loudhvx) designed. I suppose I should also get some B6ES plugs, I've been using B7ES, as that is what is readily available at a normal price, not having to have the other ordered.

Well, I would try it as you planned first. You don't want to buy stuff if you don't have to. If your NGK caps have the resistor, then you don't need resistor wires, but I'm not sure if resistor wires with resistor caps is necessarily bad or not.

If it turns out you need a lower resistance coil for high RPMs, then you could buy another car coil and try them with the primaries in series. A single dual-output coil would probably end up much neater. Or you could try to build the ignitor, for your bike, it would only come down to soldering 4 components.

Thanks for the input. Right now I am not using the NGK caps (which are 5K ohm), it's just the automotive plug wires cut to length with coil connectors crimped to the end that used to hace distributer cap ends.

I think I will try it first with the HD coil. If it turns out to not work with the 3 ohm coil, it would just show a symptom of not revving to red line? If that is the case, I think I can handle building the ignitor ( I didn't have an issue building the Megasquirt). I have LOTS of experience with soldering (and as a QA engineer in an electronics mfg. co.).

Hopefully I can get to this over the next couple of days. I'll keep everyone posted...

yep, here I am with two posts in a row again! I just started looking at the manual again (the internet is a wonderful thing) and found this:

Ballast Resistor
If your vehicle has a ballast resistor in line with the coil wiring, it is not necessary to bypass it. This is because the HYFIRE® VIA Ignition Control receives its main power directly from the battery.

Seems to me, this means that it really doesn't matter what the coil primary resistance is, this thing should be able to fire it at any rpm (up to its limit, can be set for up to 12000 rpm limiter, or disable the limit)

As part of the installation, don't you have to hook up the coil to the Mallory directly? That would then eliminate any ballast entirely.

I'm still trying to decide if it's good to solder to the HEI terminals or not. They are meant for spade connectors.... I guess I'll try and see.