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Arcing on the flywheel


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I'll just make a ground strap to be safe. Another thing I noticed is I'm running a deutch connector harness with gold plated pins(mostly used in ECM connections) and sockets. red wire off the stator is arching as well

 

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It won't hurt in anyway.

So I don't see why people wouldn't have one.

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Figured I would pop my head in to try to explain some of our findings on flywheel/crankshaft interface issues.  

 

What we determined is a condition called "fretting" which is common with tapered shaft interfaces if there is not consistent and uniform contact between the two mated parts.  During high speed operation and function, the mated parts tend to vibrate locally causing localized heating, galling, welding, etc.  Depending on the severity, this can appear as strange lines or colors in the interface, all the way to welding of the components.  

 

In a severe case that we analyzed where the crank had to be chopped off due to welding, we determined a large amount of runout from either improper installation of the flywheel, or improper contact of the tapered components.  

 

We recommend using lapping compound if the taper quality is in question and lightly rotate the flwheel without the key to set in consistent contact.  It is also always a good and prudent idea to test the TIR of the flywheel with a dial indicator to verify it is running true.  Runout or TIR will cause vibration, heat, and excessive radial forces on the crank bearings.  

 

Brandon

Mull Engineering

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All grounds already go back to the same black wire. It's not like a car with a battery.

 

I stand by my stance that zero grounds are needed. No need to sand your pc or oven worry about the coil being grounded.

I can agree with this to an extent but I will offer a few things here while trying not to make this into a novel.  

 

There must exist two sides to a circuit, if you will, an "in" and an "out".  the ignition coil produces 5-7KV through a single lead and the ground strap side on the spark plug provides a path for the current.  If you will notice, if you hold a spark plug lead out in air, it will not arc because it has no path to discharge.  

 

Now, it gets deep fast in this stuff but the terms are "ground reference" and "floating ground".  All a ground is, is the "out" side of the circuit.  We decide what that out side references to.  We use the term "earth ground" when we couple the out side to the earth thus keeping all things touching the earth at the same potential, which is zero.  

 

I guess what I am saying is you can certainly get spark from the "in" side to the ground strap or "out" side of the plug when there is a path for current to flow, but it becomes a really good idea to keep all things referenced to the same ground to keep people from being shocked or things getting damaged.  When an engine is accepting the current from the plug but the chassis is not coupled, we don't know what the potential is of the chassis, this is when people get shocked, or things get zapped.  

 

I will try an example, the low voltage transformer for a home because it is almost identical to an ignition coil.  It has current flowing on the primary and nothing even cares where it gets its current flow or references, the secondary is isolated, but we take the center tap of that secondary which is the "ground" and we "reference" it to earth because we most certainly do not want  a floating condition where there is potential (potential voltage discharge) between ground and neutral.  We want those to be the same for safety of people and devices.  

 

The potential can be understood by grabbing say the POS lead of a 50VDC battery.  No shock!  Only when you touch both do you get current through your girly arms.  This same thing can happen when you touch a floated ground vs some other chassis that has a different ground reference.  

 

I am probably rambling.  

 

Brandon Mull Engineering

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Been a while since the HQ has had any kind of good reading / posts !

That's because:

-People complain every time something is more then a sentence. (Those same folks are also the people who complain when there's minimal info.)

-People would rather you search old shit rather then get a fresh take on an old issue.

-People tell you to just pay a builder rather then trying to figure it out.

-Some mother fuckers know everything.

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In the electrical field where you ground also makes a difference. Electricity is stupid and takes the path of least resistance so bonding the first means of disconnect is crucial for safety. I've been on many calls where plumbing pipes have current on them because of a homeowner lack of knowledge. In higher end grounding rings everything is directional to keep equipment safeguarded . When you get shocked on your quad your an easier path than the grounds you have in place and need to address the problem. As for flywheel problems I always use locktite, it fills in problems areas that lapping can't get , if you've ever lapped anything before you know it's limited

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Sleeper, the lapping I refer to may be misunderstood as I don't advocate for any real metal removal because you can make the problem worse.  This is by using only FINE paste with approx 600-800grit.  The way we have chased the problem is by using Hi Spot blue marking paste to see the contact made between parts.  In most cases, some sort of installation error has occurred around the key or the key was not set properly. 

 

 

The runout or TIR is the main thing to check.  A flywheel that is running correctly will show TIR of less than .001".  We have seen TIR of .010" which is WAY too much to operate safely. 

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I can agree with this to an extent but I will offer a few things here while trying not to make this into a novel.  

 

There must exist two sides to a circuit, if you will, an "in" and an "out".  the ignition coil produces 5-7KV through a single lead and the ground strap side on the spark plug provides a path for the current.  If you will notice, if you hold a spark plug lead out in air, it will not arc because it has no path to discharge.  

 

Now, it gets deep fast in this stuff but the terms are "ground reference" and "floating ground".  All a ground is, is the "out" side of the circuit.  We decide what that out side references to.  We use the term "earth ground" when we couple the out side to the earth thus keeping all things touching the earth at the same potential, which is zero.  

 

I guess what I am saying is you can certainly get spark from the "in" side to the ground strap or "out" side of the plug when there is a path for current to flow, but it becomes a really good idea to keep all things referenced to the same ground to keep people from being shocked or things getting damaged.  When an engine is accepting the current from the plug but the chassis is not coupled, we don't know what the potential is of the chassis, this is when people get shocked, or things get zapped.  

 

I will try an example, the low voltage transformer for a home because it is almost identical to an ignition coil.  It has current flowing on the primary and nothing even cares where it gets its current flow or references, the secondary is isolated, but we take the center tap of that secondary which is the "ground" and we "reference" it to earth because we most certainly do not want  a floating condition where there is potential (potential voltage discharge) between ground and neutral.  We want those to be the same for safety of people and devices.  

 

The potential can be understood by grabbing say the POS lead of a 50VDC battery.  No shock!  Only when you touch both do you get current through your girly arms.  This same thing can happen when you touch a floated ground vs some other chassis that has a different ground reference.  

 

I am probably rambling.  

 

Brandon Mull Engineering

 

 

 

 

 

I don't doubt your knowledge on this at all. 

 

But do not all of the black wires already connect together and ground themselves to the engine? The only reason I can see for a frame to engine ground is if you chose to use the frame as a ground for one of the components (like how pvl coils ground to the frame.) I can see no reason in a perfectly functioning ignition system why the voltage would choose a path other than back through the ground back to the engine that is already in the wiring harness....but electricity does funny shit I guess.

 

If there is a short, bare wire or malfunction of sorts, I can see where it could be a safety issue with getting shocked....but this can happen even with the frame ground. The way I hook up the tether (one lead to each side of the coil) this has happened before. Usually just swap the leads on the tether and this goes away.

 

My bikes have 1000s of passes and/or dyno pulls with no frame to engine ground....or any part of the ignition grounded to the frame for that matter.

 

 

I didn't come up with this idea on my own, in drag racing it's "monkey see, monkey do!" I saw how someone had their ignition wired with a very simple method, and that guy definitely had his shit together. We discussed what was going on with the wiring and he said basically what I'm saying.

 

 

I appreciate the technical info on why the ground could be needed...and the rationale for it.

 

If (very rarely) we have to switch electrical components to rule out issues, it only takes a few seconds the way all of mine are wired.

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