Engine dies randomly while riding

[mcquillr]

Inspect the fuse(or swap it for a new one because just looking at it doesn't always do it...and look at wiring in general.

This isn't a bad idea though. I don't know if the fuse has ever been changed.

[Brendan W]

Might be worth getting it running and then take off the side cover and start pulling at wiring, particularly the fusebox tail and anything ignition related. The coil supply plug can hide a mess of corrosion even though it looks fine on the outside.

[mcquillr]

Might be worth getting it running and then take off the side cover and start pulling at wiring, particularly the fusebox tail and anything ignition related. The coil supply plug can hide a mess of corrosion even though it looks fine on the outside.

Also a good idea.

So we are all pretty certain this isn't a fuel delivery issue then?

[Brendan W]

Also a good idea.

So we are all pretty certain this isn't a fuel delivery issue then?

Well I'm not betting my house on it.
Loss of ignition feels different to loss of fuel. I can't really explain it. Fuel starvation can gradually lose power and then finish with a flourish and maybe a lean backfire or two. Loss of spark is different,
How would you describe the power loss ?

[mcquillr]

I would say its a quick loss of power, maybe over the course of 3-5 seconds, no backfiring just dies.

[Eli69]

One of my old gs 's has an ignition switch that doesn't always make contact. It has occasionally turned off while riding. With no warning. Usually I just wiggle the key. All the electric stuff turns off. Just a thought.

[mcquillr]

Yes I was thinking of trying to bypass my ignition switch to see what happens.

[Gorminrider]

yes and the kill switch too....but if it's not electrical, you are going to have to go back to gas supply..

I rode the rest of the way home with the petcock in Prime mode but the engine died a few times along the way.

...any change when pulling the choke when the bike is slowing? would be somewhat a test for supply in the bowls themselves... floats hung up.. less likely, needles stuck which is more common for rubber-tipped than these..

I am guessing this is your setup then? Perhaps you got a defective kit-it's possible. and they have a note per wanting suppression plug caps too. So you might want to clean those up if they are the originals and/or get plugs that have suppression...The suppression stuff is part of the secondary's impedance and might affect heating at the coils if that were a thought...

ignitionKit.jpg

..It might be in all that heavy black text I can't read but the kit seems targetted to later models than yours (80-83? GSX400 and GS450 ) but I can't see why it would matter beyond a slight difference in timing..not the issue here.

..if the coil is getting hot unless you can get one of those battery operated indoor/outdoor thermometers. The sensor would be on the coils or any thermom that saved Highest temppp...might do. ie part of the "always check the last thing you did" Especially so if the bike was running properly before you did it...but did it ever?

after I found someone had grinded down the lobes of my advance mechanism

[posplayr]

I'm wondering why you chose to eliminate one of the coils?
One of the reasons that Suzuki uses two coils is to give the coil sufficient time to recover. The faster the RPM the less time there is.

If you have one coil it has to run twice as fast which means it is not likely to fully magnetize the coil when the ignition is fired. It could be also causing the coil to get hotter than normal and further reduce its output.

I would go back to two stock coils and wire as per the manual. See if that keeps it from stalling.

[mcquillr]

yes and the kill switch too....but if it's not electrical, you are going to have to go back to gas supply.. ...any change when pulling the choke when the bike is slowing? would be somewhat a test for supply in the bowls themselves... floats hung up.. less likely, needles stuck which is more common for rubber-tipped than these..

Yes and I very recently rebuilt and cleaned out the carbs so I would suspect they are in good shape.

I am guessing this is your setup then? Perhaps you got a defective kit-it's possible. and they have a note per wanting suppression plug caps too. So you might want to clean those up if they are the originals and/or get plugs that have suppression...The suppression stuff is part of the secondary's impedance and might affect heating at the coils if that were a thought...

Correct, this is my setup. I did change my plug wires when I swapped my coil. I switched them out with 7mm Dynatek Copper plug wires. I can email Boyer-Brandsen and tell them what is going on. Maybe this is a defective kit.

..if the coil is getting hot unless you can get one of those battery operated indoor/outdoor thermometers. The sensor would be on the coils or any thermom that saved Highest temppp...might do. ie part of the "always check the last thing you did" Especially so if the bike was running properly before you did it...but did it ever?

It's definitely running better with the EIS installed. I couldn't physically set the advance timing with the stock setup. That's what led me to check the advance unit and to find that someone had shaved down the one of the lobes.

[mcquillr]

I'm wondering why you chose to eliminate one of the coils?
One of the reasons that Suzuki uses two coils is to give the coil sufficient time to recover. The faster the RPM the less time there is.

If you have one coil it has to run twice as fast which means it is not likely to fully magnetize the coil when the ignition is fired. It could be also causing the coil to get hotter than normal and further reduce its output.

I would go back to two stock coils and wire as per the manual. See if that keeps it from stalling.

My reasoning here is that no matter if you have one or two coils they both will always be working twice as fast so there shouldn't be any difference between having one or two. Am I misunderstanding how the system is working?

[Gorminrider]

I switched them out with 7mm Dynatek Copper plug wires.

Ok..but...how about the spark plug caps> using the old ones? Coils are not meant to run straight to the spark plug unless it's a lawn mower...You are aware that the original plug caps had 5000 ohm resistors in them? If you are running just straight copper with a different kind of cap without this xtra impedance....? I

or, it's been said that you can get the necessary impedance from the plugs themselves...a not-so-wild guess for your bike is that these should be NGK DR8ES-L the L being the indicator of impedance...
Mainly to say, I would not be running the bike without at least one or the other of these and both together works fine for me on an 81 with the stock ignition.

[posplayr]

My reasoning here is that no matter if you have one or two coils they both will always be working twice as fast so there shouldn't be any difference between having one or two. Am I misunderstanding how the system is working?

I'm not sure I see any reasoning.

If Suzuki could have made it work with a single coil they would have done that.

It basically gets down to this. A four-cylinder engine is two 2 cylinder engines. The main complication is how they are fired. A 4 cylinder fires twice every revolution of the crank. but because of wasted spark, there are actually double sparks going out (i.e. 1-4 or 2-3) A 2 cylinder also fires twice per crank revolution and it is also wasted spark.

So how can you fire twice per revolution with a single coil and get the same charge/saturation time to build up the magnetic feild?
The answer is you can't which is why you need two coils and is why the same ignitor will work.

[pdqford]

It basically gets down to this. A four-cylinder engine is two 2 cylinder engines. The main complication is how they are fired. A 4 cylinder fires twice every revolution of the crank. but because of wasted spark, there are actually double sparks going out (i.e. 1-4 or 2-3) A 2 cylinder also fires twice per crank revolution and it is also wasted spark.
.

Okay, I’m trying to follow along here.
On the four cylinder Suzuki the “paired” cylinders, I.e., #1 and #4 move up and down together and therefore can use what is referred to as a “wasted Spark” ignition system, where the companion plugs fire at the same time, but one is on the power stroke and the wasted spark is on the exhaust stroke.

Now I’m not familiar with this 2 cylinder engine you speak of, but I have had a Honda 305 Dream with a twin cylinder where both pistons move up and down together ( so it could use a wasted spark system in theory) and I have had a Honda 305 Super Sport twin where the pistons move up and down opposite of each other ( think John Deere Johnny popper style) and have unequal firing pulses, which would not support a wasted spark ignition system because of the uneven firing impulses.

So which style twin are we talking about?

[mcquillr]

Now I’m not familiar with this 2 cylinder engine you speak of, but I have had a Honda 305 Dream with a twin cylinder where both pistons move up and down together ( so it could use a wasted spark system in theory) and I have had a Honda 305 Super Sport twin where the pistons move up and down opposite of each other ( think John Deere Johnny popper style) and have unequal firing pulses, which would not support a wasted spark ignition system because of the uneven firing impulses.

So which style twin are we talking about?

I am under the impression that my bike, stock, uses the unequal firing pulses method. I'm pretty sure my bike has a 180º crankshaft. My original points system would fire each plug separately, not together.