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In my first thread about "spark plugs" the Italion Stalion wrote that the 1800 fires the plugs on the exhaust stroke as well as the compression stroke. Do we have any experts out there that can confirm or deny that statement? :?: :?:
 

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GL1800 Doctor
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The 1800 only has 3 coils, so everytime there's fire, 2 cylinders get it. 1&2, 3&4, 5&6 so they all can't be on the compression stroke. :D
 
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The 1800 only has 3 coils, so everytime there's fire, 2 cylinders get it. 1&2, 3&4, 5&6 so they all can't be on the compression stroke.
I can't answer the question either techdude :shock:

ha ha ha just messing with ya :wink:
 

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GL1800 Doctor
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JudgeDredd331 said:
The 1800 only has 3 coils, so everytime there's fire, 2 cylinders get it. 1&2, 3&4, 5&6 so they all can't be on the compression stroke.
I can't answer the question either techdude :shock:

ha ha ha just messing with ya :wink:
Funny funny, you know I can't find any timing info in the service manual other than checking the marks with a light. The ECM handles it so I guess Honda doesn't think we have a need to know. :shock: :?
 

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:hun1: 3 COILS, 2 CYLINDERS GET IT, 1&2, 5&6, 8&9 :a13: . . . . . . . . . WHAT??????

IS THIS SOME KIND OF KLINGON CODE FOR "RAISE THE SHIELDS?" :twisted:

OR PERHAPS A BIT TO MUCH :beer8:
 

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:hun1: 3 COILS, 2 CYLINDERS GET IT, 1&2, 5&6, 8&9 :a13: . . . . . . . . . WHAT??????

IS THIS SOME KIND OF KLINGON CODE FOR "RAISE THE SHIELDS?" :twisted:

OR PERHAPS A BIT TO MUCH :beer8: ON MY PART :capwin:
 

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Even if they fire on the exhaust stroke (they probably do), there is little charge in the cylinder at that point and the coil won't need to produce very much voltage to jump the gap. In other words, it won't affect plug life much if that's your concern.
 

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GL1800 Doctor
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WingAirSpeed said:
:hun1: 3 COILS, 2 CYLINDERS GET IT, 1&2, 5&6, 8&9 :a13: . . . . . . . . . WHAT??????

IS THIS SOME KIND OF KLINGON CODE FOR "RAISE THE SHIELDS?" :twisted:

OR PERHAPS A BIT TO MUCH :beer8: ON MY PART :capwin:
8&9 ? :?
 

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It's been like that for years. I first noticed it on my 1973 Suzuki GT185 twin. It only had one coil and both spark plugs connected to it. Every other bike since then, except the big single, has had only one coil for two cylinders. I have also noticed this on many cars since then. I do believe it helps lower emisions by burning the unburned fuel in the exhaust.
 

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GL1800 Doctor
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My 94 750 Virago had separate coils for each of the 2 plugs and fired at their own respective times. :sparkplug:
 

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MotorcycleBoy said:
It only had one coil and both spark plugs connected to it.
I've had many a V-8 that had only one coil hooked to 8 spark plugs. They fired individually and only once per 4-stroke cycle. It's not the coil that determines the firing. Back then it was the distributor and points that did it. Today it's all electronic... don't have a clue why they would fire on the exhaust stroke - maybe emmision related?
 

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don't have a clue why they would fire on the exhaust stroke
Didn't you get the memo on the afterburner??...... Or maybe it's just on the faster RED ones...:D
 

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Wanderer said:
MotorcycleBoy said:
It only had one coil and both spark plugs connected to it.
I've had many a V-8 that had only one coil hooked to 8 spark plugs. They fired individually and only once per 4-stroke cycle. It's not the coil that determines the firing. Back then it was the distributor and points that did it. Today it's all electronic... don't have a clue why they would fire on the exhaust stroke - maybe emmision related?
My guess would be to help the burn continue for lower emissions also.
Each coil on the 1800 has both plugs firing together from a single pulse from the ECM. Easy and no moving parts... I like it. :D
 

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Wayne,
There is a very good answer as to why the plugs fire on the exhaust stroke. Many of the guys have given good answers, but haven't explained why it has to be that way. This is long winded, but bear with me.

The system we are talking about is commonly referred to as a lost spark, or wasted spark system. From a technical standpoint it is called DIS or Distributorless Ignition System.

Back when we had distributors, we had only one coil and that is all we needed. The ignition fired the coil 6 times every full cycle (two revolutions) of the engine in a 6 cyclinder and the distributors whole purpose in life was to route the high voltage to the correct spark plug.

Once they eliminated the mechanical distributor, all of a sudden there was no way to route the high voltage. One solution was to use 6 different coils and mount them directly on the spark plug. Obviously this is called a coil on plug design. Ford has been using this system for many years. There are no high voltage spark plug wires, just thin low voltage trigger wires. The ignition has 6 different wires coming out of it and can fire each one individually, so the spark plugs only fire on the compression stroke.

The lost spark system is even more common then the coil on plug design because it is cheaper. It uses only 3 coils for a 6 cylinder engine, with each coil being responsible for 2 spark plugs. This creates a problem. How are you going to send 6 signals to the spark plugs with only 3 coils. The coil has no control over which spark plug gets the 40,000 volts, so they have to fire both.

Here comes the hard part to understand. Each coil has two wires coming out of secondary high voltage side, with one going to each spark plug. But something is missing right? Where's the ground wire? In the distributor systems and coil on plug designs, one end of the coil is grounded but this is not true in the shared coil system. By connecting each wire to one of the spark plugs you have essentially just connected the spark plugs in series. They are connected together through the engine block. Since the coil is not grounded, it does not see the block as a ground like the battery does, so the coil and plugs can use the block just like it was a piece of wire connecting the plugs together.

Here is the path. When one plug is on the compression stroke, the ignition sends 12 volts to the coil which is increased to 40,000 volts and sent to the spark plug by way of the spark plug wire. The current flows from the center electrode across the gap to the ring of the plug and into the block. From there it travels through the block to the ring of the other plug on the exhaust stroke, across the gap of that plug, to the center electrode, through the spark plug wire and back to the same coil, completing the current path. The process is reversed when the other spark plug has to fire.

As you can guess, since the plugs are connected in series, if one plug were to fail, the other plug would not fire either, which is a good reason to keep good plugs in the bike because you would lose two cylinders if one plug were to fail.

This system may seem inefficient, but don't forget that when you had a distributor, there was essentially a wasted spark to the distributor cap, so this is really nothing new.

I hope this helps. I couldn't think of a way to make it short.
 

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LarryM said:
... The ignition fired the coil 6 times every revolution of the engine in a 6 cyclinder ....
Good description, Larry. But one minor point here: The coil sparked 3 times for every single revolution of a six cylinder, four cycle engine. There was one power stroke every 120 degrees of rotation, which means three in 360 degrees, and six in 720 degrees.

LarryM said:
... The process is reversed when the other spark plug has to fire. ....
Not necessarily reversed because you still get a spark at both cylinders by just repeating the process. BTW, the difference in polarity of the spark at the two cylinders is why some cars specify two different part numbers for the spark plugs. (ie: 3 of one type and 3 of the other)

LarryM said:
... and when we had points there was a second wasted spark with each firing of the spark plug.
Yep, but that spark was in the primary side, not the secondary side, so can we really count that one? Besides, you really didn't get much of a spark if your condenser was good. :wink:

Overall, you did a good job of describing the different systems!


 

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GL1800 Doctor
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Interesting, I know the primary sides of the 1800 coils are grounded, but can't find any info on the secondary sides. :?
 

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techdude2000 said:
Interesting, I know the primary sides of the 1800 coils are grounded, but can't find any info on the secondary sides. :?
Look at the bottom of page 17-0 (in my '02 service manual). Two plugs are in series on the secondary side of each coil (one on each end), and one plug will always get a 'positive' spark and the other the 'negative' spark.
 

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All Boots,
:lol: :lol: :lol: You got me on one technicality and one serious boo boo. I deleted the brain fart. I was typing really fast and didn't stop to think. Thanks for pointing out the errors.

As far as the polarity goes, I don't know why, because as you say, it shouldn't matter, but they really do reverse the polarity on many of these systems. . When on the compression stroke, the current, (and the spark), travels from tip to ring, and on exhaust it travels from ring to tip. There may be some systems that don't differentiate it, but I know that many do.

After looking at the Honda schematic it is obvious that they do not reverse the polarity since one side of the primary is grounded. If it were a differential input to the primary with no ground, then it would be a reversing type system. Since we are talking about the Goldwing I should have just left that part out to avoid confusion.

I figured you would follow it, but I hope it made sense to everyone else. :?
 

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LarryM, you did good. You know guys, we could argue who is right or wrong or who made a mistake but the truth is; there are as many correct answers for this question as there are auto and motorcycle manufacturers. Back in the '80s I saw a Japanese car, possibly Nissan, that routed the spark to two plugs at the same time through a double tipped rotor in the distributor. The motor had two plugs per cylinder, 8 plugs, 4 cylinders. Interesting isn't it. :D
 
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