coils

Maybe a dumb question...do you have to remove the paint from the frame where the coils mount?

 

No, but.........typically there are some harness ground wires that attach to the rear bolt that holds the stock coils to the frame. Those ground wires do require a really good ground. In fact, it's never a bad idea to make up a proper length ground wire (14g wire will be just fine) to run from those ground wires directly back to the battery negative terminal post........proper size ring terminals at each end for attachment.

 

Thanks Len! Sounds like a good idea.

 

You can simply wrap some 320 Sandpaper around a Screwdriver Shaft and sand the rust and paint from the Ground point.

Dress the Terminal Ends of the Ground Wire with an Emory Board to shine it up and Grounding the Wire to the Frame will be the same as running a Ground Wire all the way to the Battery Post.

Dress the Battery Post.
Dress the Ground Strap ends.
Make sure the Ground Strap is tight to the Battery and Grounding Post on the Engine.

 

Chacal may be right, but when I removed my coils from the frame, there was bare metal on the frame right where the coils mount. I plan to mask off the area when I get the frame PC'd.

 

In that case, ... you can join the Coil Grounds together and splice on a Wiire that can be run to the Ground Wire inside the Headlight Bucket.

 

Very good ideas, thanks!

 

When I powder coated my frame I didn't clean off the powder coating from the coil mounts, but I did run a ground from the engine to the coils.

In fact I have no intentional frame grounds.

 

There's really no reason have a ground from the coils, other than to drain any residual field collapse current.

The TCI side grounds through the TCI (duh) and the HT side grounds through the spark plug.

 

There must be some good reason.

Maybe the Coil Windings need a path to Ground to energize the Coil?

 

Electricity needs a complete circuit. There has to be a ground on the high tension side or the electricity won't flow.

The high tension side will find a ground - even if it has to overcome a lot of resistance. If it's not grounded where you want it grounded it might find a path (like through the TCI) that you don't want.

 

Just to be clear, the grounds that I am referring to come off of the MAIN WIRE HARNESS for the bike, and thus provide a grounding path for a variety of different circuits. The ignition COILS themselves do NOT ground onto the frame; it's merely that the rear support bolt for the coils is where the factory attached (on many models) a MAIN HARNESS ground wire(s).

 

yoy, the tci pulses the ground, the + is always there. the (primary) low side builds a magnetic field when the tci connects - to the coil. when the tci takes the - away the magnetic field collapses and induces a high voltage in the (secondary) high side.
this is where it gets tricky.
the path the spark takes is out the plug wire, across the gap thru the engine across the other gap and back the other plug wire.
that makes a whole circuit and the motor goes

 

I have looked at the schematic in the Haynes book, it does not indicate that the coils need to be grounded at their mounting point. I guess it was just coincidental that there was no paint on my frame where the coils mount.

 

I'm pretty sure there's one part of that wrong Polock.

When the high side collapses, it doesn't go through one, through the engine and back UP the other. When the Mag field collapses, it kinda "splits" and sends half down one plug wire, and half down the other. They both fire and the charge is resolved to ground (-Batt through engine strap)

It would make no sense, that it would send out one, then back IN the other (Somehow ignoring the ground and jumping air again). The resistance is so high, it wouldn't be able to pick one lead over the other to spark how you are suggesting Pol

Also, that would mean that the ignition would fire without having the engine grounded.

 

The way Yamaha has designed the coils is very common; one coil with 2 plug wires. Both plugs fire at the same time, this is not a problem as one piston comes up on compression, it's shared piston is coming up on exhaust. This is known as the wasted spark. If there are unburnt gasses in the wasted spark cylinder, you will get a very nice backfire.

 

think of it this way 2 separate circuits, the bike and the coil secondary.
the bike is ground, really it's the - side of the battery, we call it ground. but you can't have a - side without a + side. so the engine is only ground (- battery) in relation to the + side of the battery. (i'm getting lost here ).
so when the mag field collapses it induces a voltage in the sec coil, two wires on the secondary coil, one becomes + , one becomes -, but only in relation to each other.
the 1 connection the the 12v system has no effect.
we skipped harmonics and earth ground but that gets real deep and doesn't really apply here

 

Yeah, but this is where the real interesting stuff happens!

So how do you get rid of audio system ground loop hummmmmmmmmmmmm.......?

 

example, say you hooked a bike battery - side to the black hot wires of your house fuse box and measured the voltage from the + battery to - battery......12 volts. now measure from - battery to the white side of the fuse box, 110 volts. their connected but still separate

 

shut the engine off

 

I think you should be thinking of this in terms of current, not voltage tho. Current isn't going to jump a Mohm air gap when it can just goto -

 

Now that i've researched it a bit, Polock is right, and my brain hurts lol I can't grasp that right now.

 

This new enlightenment, begs the question: Are our TCI's smart enough to reverse the primary windings current, for optimal power stroke spark.

If so, wouldn't it be a good idea to know what secondary output, should be going to the power stroke cylinder?

Now my head really hurts lol

 

they don't have to the spark works just as well going from tip to strap as strap to tip(on the plug)
look up the left hand rule for magnetism and current flow that's what determines the polarity of the secondary voltage.
here's something to really make your head hurt.
a battery is marked + & - , you would think current flows from + to - but it really goes - to +. think about that and you'll go nuts

 

I totally get the - to +, learned all about the switch of that back in highschool. I had just read a lot about how the casing to center spark isn't as strong as the centre to casing spark.

Guess I stopped my electronics engineering tech classes too early to get the mag field stuff lol (Was only in for a semester and a half or so, looking back I wish i stayed with it)

 

No. The TCI switches the coil negative to ground, repeatedly. The positive is hard wired so it is not possible for the TCI to change the polarity.

Wasted spark is used on a LOT of modern engines, and even though one plug takes a slight amount more to fire, the coil has plenty of reserve so it really does not matter.

 

yEAH THAT IS A TRIP, i finally just marked arrows indicating current direction on certain parts of my schematics.That helped alot to get my head wrapped around that concept.

 

How big of a deal is the primary resistance on the coils? I have zero resistance(continuity) when I tested them, however they still seem to work fine, is this going to draw current all the time if I dont have an inline switch?