Grounding the head

pete.v · Jun 19, 2015

comnoz said:
1up3down said:

Neither the head nor any part of my engine is grounded to anything.

What am I missing, and why does everything electrical function perfectly for many years now without this grounding?

Click to expand...

Well if you have two separate ignition coils then all you need is enough ground to flow around .02 to .05 amps. A drive chain or clutch/throttle cable will easily supply that.

If you have a single coil then you don't even need that to run correctly -although a ground would be a good idea to prevent electronic ignition module damage if you have an open plug wire. Jim

Ya, Jim, Go get em.

Anonymous · Jun 19, 2015

Here's me thinking we were discussing "Grounding the head".
With the clutch cable or drive chain?
Goodo with that!
Ta.

comnoz · Jun 19, 2015

pete.v said:
comnoz said:

1up3down said:

Neither the head nor any part of my engine is grounded to anything.

What am I missing, and why does everything electrical function perfectly for many years now without this grounding?

Click to expand...

Well if you have two separate ignition coils then all you need is enough ground to flow around .02 to .05 amps. A drive chain or clutch/throttle cable will easily supply that.

If you have a single coil then you don't even need that to run correctly -although a ground would be a good idea to prevent electronic ignition module damage if you have an open plug wire. Jim

Click to expand...

Ya, Jim, Go get em.

Aaaa, It won't make any difference. Old wives tails rule over physics any day....

comnoz · Jun 19, 2015

needing said:
Here's me thinking we were discussing "Grounding the head".
With the clutch cable or drive chain?
Goodo with that!
Ta.

Don't get me wrong. I do recommend a ground wire somewhere. [Preferably where it will not break off.] Jim

1up3down · Jun 19, 2015

If you have a single coil then you don't even need that to run correctly

exactly what I have, a single coil, and no grounding motor wires

comnoz · Jun 19, 2015

1up3down said:
If you have a single coil then you don't even need that to run correctly

Click to expand...

exactly what I have, a single coil, and no grounding motor wires

In that case the currant flow is out one plug wire and back in the other plug wire.

I would still recommend a ground wire somewhere. Jim

Hobot · Jun 19, 2015

Ugh real issue... is not that spark may fail w/o a special earth return as that there is plenty of voltage to push the small current back to parts that connect to batter but pulses between the bearing elements over time tends to electro erode their closest load bearing contacts.

Snorton74 · Jun 19, 2015

How about putting a ground wire here... Mine pairs up with the three phase alternator wires and runs up into the battery compartment to a common ground.

comnoz · Jun 19, 2015

Snorton74 said:
How about putting a ground wire here... Mine pairs up with the three phase alternator wires and runs up into the battery compartment to a common ground.

That works just fine. Jim

Hobot · Jun 19, 2015

Neat way to route an engine earth but that area gets grimy easy so may interfere with satisfying wipe downs. Red traditionally connects to the + battery terminal.

gortnipper · Jun 19, 2015

Just disconnected the ground to the head, and measured 1.2 ohms R with my CAT IV meter between head (next to plug) and battery terminal.

comnoz · Jun 19, 2015

gortnipper said:
Just disconnected the ground to the head, and measured 1.2 ohms R with my CAT IV meter between head (next to plug) and battery terminal.

So if your running a conventional ignition and it is firing the plug at around 12000 volts you will be passing about .03 amp through whatever ground you have.

With 1.2 ohms resistance you will be loosing .036 potential volts across the plug. Suppose you will miss it?

I wouldn't be surprised that if you connected the wire back up and measured the resistance from the head to the battery ground it would still be pretty close to the same. Jim

gortnipper · Jun 19, 2015

comnoz said:
gortnipper said:

Just disconnected the ground to the head, and measured 1.2 ohms R with my CAT IV meter between head (next to plug) and battery terminal.

Click to expand...

So if your running a conventional ignition and it is firing the plug at around 12000 volts you will be passing about .03 amp through whatever ground you have.

With 1.2 ohms resistance you will be loosing .036 potential volts across the plug. Suppose you will miss it?

I wouldn't be surprised that if you connected the wire back up and measured the resistance from the head to the battery ground it would still be pretty close to the same. Jim

.35 ohms. Dont suppose I'll miss it. And I won't miss the wire.

edit: RITA soon to be Trispark

Hobot · Jun 20, 2015

Ok if so little amp pluse to conduct and nil loss of spark gap jump voltage and can ride with the wind w/o engine earth wire - why use another fault prone needless Commando engine wire back to + battery?

pete.v · Jun 20, 2015

hobot said:
Ok if so little amp pluse to conduct and nil loss of spark gap jump voltage and can ride with the wind w/o engine earth wire - why use another fault prone needless Commando engine wire back to + battery?

I think sitting static resting on metal to metal readings, particularly on centerstand, may change state while rumbling down the road at 4000rpm. Maybe with most it is precautionary, but maybe with some it is vital. I would not dismiss it.

What's the old Commando adage? Oh ya, you can't have too many ground wires.

Hobot · Jun 20, 2015

Best I can find is its bad juju over time to have any current flowing between moving surfaces or errodes the surfaces the electrons must cross. For extra credit trace the potential paths of electrons from battery to spark gaps and count the moving surfaces electrons must cross. Might be enough surfaces sharing the flow so hardly any erroding but someone must of found out its not good long term situation. My view is with non conductive oil wedge spearating most surfaces at speed various varying places are getting a concentration of electrons that would pit and errode faster than expected.

gortnipper · Jun 20, 2015

Btw, was not on center stand but both wheels down and in rubber lined wheel chock.

SteveA · Jun 20, 2015

hobot said:
Neat way to route an engine earth but that area gets grimy easy so may interfere with satisfying wipe downs. Red traditionally connects to the + battery terminal.

No Steve, my bike gets grimey, your bikes get grimey, but the one in the pictures seems immune.... :?

pete.v · Jun 20, 2015

gortnipper said:
Btw, was not on center stand but both wheels down and in rubber lined wheel chock.

Fair enough. How were the reading at 2,3,4,and 5000 rpm's? Nice and steady? No varience?

gortnipper · Jun 20, 2015

Grounding the head

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