Author Topic: non wasted spark cb750 igniton? (Read 10465 times)

bucky katt · « **on:** August 15, 2009, 11:02:20 AM »

is there a non-wasted spark ignition/coils for the sohc 750's? has there ever been such an animal? from what i've learned from wrenching on old bikes since the early 90's and my time at AMI and working at various shops, it would seem that a non wasted spark ignition would be more energy efficient. i've also heard it called a single fire ignition from my harley friends.

Gordon · « **Reply #1 on:** August 15, 2009, 11:52:51 AM »

It's an interesting idea. I wonder if the power consumption of either an electric unit to control the spark or a mechanical distributor would offset any gains you could get from eliminating the wasted spark?

Jim F · « **Reply #2 on:** August 15, 2009, 12:22:46 PM »

I run an old ARD Magneto that only fires one cylinder at a time
on my 750

PxTx · « **Reply #3 on:** August 15, 2009, 01:13:59 PM »

I don't really see a need to re-engineer the ignition system to be a single fire setup. You basically would have to either run 4 individual coils, or one single coil which would need some sort of distributor. With the single coil, you would not get as long of a saturation time on the coil as the wasted spark as well as the additional complication of distributing it- I don't see this worth pursuing.

The 4 coil setup has some merit, but the packaging of this weighted against some of the other improved ignition options (Hondaman system etc) brings me back to saying I just can't justify the need to design such an item.

MJL · « **Reply #4 on:** August 15, 2009, 02:04:49 PM »

A magneto. I was going to say the cycle x system, but I looked again and it is two coils.

gane · « **Reply #5 on:** August 15, 2009, 04:55:31 PM »

I may be wrong, but seem to recall a Gerex system that looked like a magneto system in the mid 70's. G

Pinhead · « **Reply #6 on:** August 15, 2009, 05:05:04 PM »

You would need 4 pickup coils (or 4 sets of points) and either 4 separate coils (COP's maybe) or a distributor. COP's would be the simplest... I don't really see a huge disadvantage with a wasted spark, though...

mlinder · « **Reply #7 on:** August 15, 2009, 05:18:22 PM »

I recall Hondaman saying he was workin on such a system, with the coils at the plugs.

Bill/BentON Racing · « **Reply #8 on:** August 15, 2009, 08:43:44 PM »

RC sold a Mallory dual pt distributor that fired one plug @ a time.ARD mag like Jim's also,the Mallory was for a Volvo or Volkswagen,same dist except for direction of rotation.I have 2 used ones from early mid 70s.Jim I'm calling tomorrow,we gotta get together,Bill

MJL · « **Reply #9 on:** August 15, 2009, 08:45:49 PM »

Quote from: mlinder on August 15, 2009, 05:18:22 PM

I recall Hondaman saying he was workin on such a system, with the coils at the plugs.

I think my cbr had coil-on-plug. If there was room it'd be cool to do that, although it'd still be wasted spark and points fired.

fishhead · « **Reply #10 on:** August 16, 2009, 09:23:51 AM »

Quote from: bellcow54 on August 15, 2009, 08:43:44 PM

RC sold a Mallory dual pt distributor that fired one plug @ a time.ARD mag like Jim's also,the Mallory was for a Volvo or Volkswagen,same dist except for direction of rotation.I have 2 used ones from early mid 70s.Jim I'm calling tomorrow,we gotta get together,Bill

Some of the Mallory units were magnetos.

This unit- called a Mallory Sprint Mag (KZ 900) had a remotely mounted coil and acted like a magneto. It threw a spark about an inch long when spun by hand. It is definetly a magneto, even though it looks like a distributor with an external coil.

RC Engineering also made distributor drives for the 4 cylinders bikes that mounted the distributor to the side of the engine and drove it through a 90 degree elbow.

Does anyone have any idea what distributors could be used for a home built system (spins the correct direction,etc)

754 · « **Reply #11 on:** August 16, 2009, 10:28:07 AM »

Correct me if you think this is wrong..

I have been in the school of thought that;
Large increase in duration, + wasted spark, can burn off some of the incoming mixture, whereas with single fire, if that does not occur... you should get more power.

Inigo Montoya · « **Reply #12 on:** August 16, 2009, 11:18:54 AM »

Hard to say about power gains or power savings but A person would be able to use smaller coils I would think as a coil would only need to power 1 plug and not 1. Besides that, I think most modern coils are smaller anyways. I have seen the rebel coils and they are about 1/4 the size of our stocks. So that would take care of PxTx's concern for that weight.

bucky katt · « **Reply #13 on:** August 16, 2009, 12:20:04 PM »

well my question seems to have been answered. i just started wondering after seeing the ignition setup on a friends 68 electra glide

BLUE71TURBO · « **Reply #14 on:** August 16, 2009, 01:03:30 PM »

Here's a pic of a distributor on a suzuki.

gane · « **Reply #15 on:** August 16, 2009, 04:44:30 PM »

Pehaps this is simplistic, but wouldn't it be a cheaper/more efficient opt to simply use andrews/dyna/whatever high output coils? (I have a couple differnt combos on current bikes) IE; stock Suz,pickups &cdi Andrews coils GS1100e,Dyna11 ign/coils.KZ1000 A1, Boyerbranson/dyna Triumph TR6C,Martec/dyna CB750k6. All have been set & forget, Is saturation time really an issue w/wasted spark ign? eager to learn, G

Jim F · « **Reply #16 on:** August 16, 2009, 05:38:39 PM »

Well I think its a personal matter of what you think will work best for your
situation. I think the cool factor of having an old Ard Mag (very impractical) compared
to current ignitions is threw the roof. My system has only one coil,. one set of points,
and the cam opens the points 4 times before it starts the process all over again, The advantage of the mag systems is that the faster you spin these the hotter the spark
but again I am after that cool factor and not allot of people see these systems on the street or the strip any more.

Pinhead · « **Reply #17 on:** August 16, 2009, 06:15:20 PM »

Holy crap, that's an ARD magneto? I have an old Tecumseh lawnmower engine with that exact same system on it!!!

Turbogrimace · « **Reply #18 on:** August 16, 2009, 06:38:36 PM »

ARD's are just an old Mag off of a tractor slapped onto a belt drive adapter. Hey Big Jim, did your mag come laying down like that? Mine stands upright and I think im going to have trouble with it clearing my VM29's. I looked at the bolt patter in my belt drive plate and it wont accomodate a simply roation of the mag.

Sorry for the stolen thread, I'll leave the needle.

BLUE71TURBO · « **Reply #19 on:** August 16, 2009, 07:00:10 PM »

Here is a picture of the next stage of the A.R.D. magnetos. After that is the CDM A.R.D. magneto like the one on my bike. The CDM "CAPACITOR DISCHARGE MAGNETO" has no points and has a toggle switch on the top base and is used
to lock out full advance so that starting is easier, then after the engine starts, you switch it over to run so that you
will get full advance. This picture is of one for a KZ1000.

MJL · « **Reply #20 on:** August 17, 2009, 12:59:07 AM »

Quote from: 754 on August 16, 2009, 10:28:07 AM

Correct me if you think this is wrong..

I have been in the school of thought that;
Large increase in duration, + wasted spark, can burn off some of the incoming mixture, whereas with single fire, if that does not occur... you should get more power.

Nah, they will be 2 rotations apart. Suck squeeze bang blow. When one is at squeeze the other will be at blow.

Now that I think about it, I suppose it's possible, but you won't have the compression to burn much if any.

MJL · « **Reply #21 on:** August 17, 2009, 01:04:29 AM »

Quote from: fishhead on August 16, 2009, 09:23:51 AM

Quote from: bellcow54 on August 15, 2009, 08:43:44 PM
RC sold a Mallory dual pt distributor that fired one plug @ a time.ARD mag like Jim's also,the Mallory was for a Volvo or Volkswagen,same dist except for direction of rotation.I have 2 used ones from early mid 70s.Jim I'm calling tomorrow,we gotta get together,Bill

Some of the Mallory units were magnetos.

This unit- called a Mallory Sprint Mag (KZ 900) had a remotely mounted coil and acted like a magneto. It threw a spark about an inch long when spun by hand. It is definetly a magneto, even though it looks like a distributor with an external coil.

RC Engineering also made distributor drives for the 4 cylinders bikes that mounted the distributor to the side of the engine and drove it through a 90 degree elbow.

Does anyone have any idea what distributors could be used for a home built system (spins the correct direction,etc)

The first time I saw a mag on a bike I was in love with it, I think it was an RC mag as it was more or less upright.

Wasn't someone here working on a plasma ignition? I wonder how that's going...

PxTx · « **Reply #22 on:** August 17, 2009, 06:14:51 AM »

I used to do some R&D for a Plasma ignition system about 10 years ago. We basically used a low voltage (500v) and a high amperage (in comparison to traditional ignition systems) but it really is impratical. Very short plug life. The metal just erodes too much.

754 · « **Reply #23 on:** August 17, 2009, 07:53:18 AM »

MJL, I am probably thinking of v-twins, I have done dozens of dual plug conversions on them, and they share a common intake plenum..

I know on Fuel 4 cylinder motors, with high compression, they said a point Ignition, just does not make a hot enough spark.

PxTx · « **Reply #24 on:** August 17, 2009, 08:01:49 AM »

Getting back to the coil per cylinder setup. Even if you had 4 coils for maximum saturation and 4 individual triggers for each cylinder you would still have wasted spark. Anyone thinking of doing anything clever for a cam sensor?

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Author Topic: non wasted spark cb750 igniton? (Read 10465 times)