Ground connection question

In another forum, some one had a problem running his bike. Eventually he found that the ground (or earth) connection was faulty. How does this affect how the bike runs?

For the past 8,500kms there have been no issues. Took the bike to work this morning and was not happy. At 100/120kmh, suddenly started running really poorly. Made it off the highway and it died whilst still moving. 20 mins later, I was still trying to start it. Eventually it fired up and I managed to limp across an intersection or two, only for it to cough, splutter and die again a few times. Made it to the office eventually. Left parked up all day. Picked up this evening, started first time. Took back roads home without any problem. $&@$!

Click to expand...

Problem arose again today. Standing there scratching my head wondering what it is and decided to pull on the bracket holding regulator and earth to frame when all of a sudden it decided to start and run. Let regulator go, and dies. Pull out tools. Oh bugger, left tools at home, call roadside rescue, pull tank, reseat the earth after giving a bit of a clean, fires up and off we go. So, root cause, a ****ty earth connection. Must be that when it warmed up enough, just expanded enough to make a poor connection. Well, that's my story and I'm sticking to it.

Click to expand...

Norbert said:

In another forum, some one had a problem running his bike. Eventually he found that the ground (or earth) connection was faulty. How does this affect how the bike runs?

Click to expand...

Every electric bit on the bike works by completed a cycle of current from one point to the other. The words earth, ground or chassis generally denote the negative path ways on a negative ground system. A negative ground system is made by a combination of electrical contacts that may use the chassis or frame and engine metal as the negative electrical pathway. So what you can do is take the negative lead from the battery and attach it to the engine, chassis/frame. Then all of the electrical circuits that need to return potential or current can use the frame/chassis or engine as part of the circuit. The chassis/ frame and engine metal are conductive.This way you can eliminate large separate groups of negative/ground wires from having to be attached to one single negative battery terminal.

What happened with your friend's bike was he lost one of those important ground connections to the frame/chassis or engine. It would be like not having a negative for that circuit.

I hope I'm making sense.

Nope......this will require some googling....
Thanks, though....

Norbert said:

Nope......this will require some googling....
Thanks, though....

Click to expand...

I aim to please.....LOL!
If you ran a wire from the positive on battery to the terminal on a light. The light won't light because current will not flow through the filament and back to the negative terminal on the battery. You have to attach the other terminal of the light to the negative lead on the battery. If you use the metal frame on the bike as a big metal negative conductor you don't have to run a long negative wire to the battery. You can use the frame as ground. You can use this frame ground as the negative path for the headlights, fuel pump, ECU, directionals, running lights, brake light and on and on. Wherever you need a ground you can use the frame as a ground as long as you have the negative cable of the battery attached to the frame. This means you just need a short wire from anything to connect to the frame.
It sounds like your friend lost one of those ground points at the frame or possibly the engine. Maybe his ECU or fuel pump or fuel injector, etc....

Motogiro said:

I aim to please.....LOL!
If you ran a wire from the positive on battery to the terminal on a light. The light won't light because current will not flow through the filament and back to the negative terminal on the battery. You have to attach the other terminal of the light to the negative lead on the battery. If you use the metal frame on the bike as a big metal negative conductor you don't have to run a long negative wire to the battery. You can use the frame as ground. You can use this frame ground as the negative path for the headlights, fuel pump, ECU, directionals, running lights, brake light and on and on. Wherever you need a ground you can use the frame as a ground as long as you have the negative cable of the battery attached to the frame. This means you just need a short wire from anything to connect to the frame.
It sounds like your friend lost one of those ground points at the frame or possibly the engine. Maybe his ECU or fuel pump or fuel injector, etc....

Click to expand...

ok. i never knew that. well, maybe i did back when i took AP Physics in high school. :tard:
been awhile....

It's in there. You just forgot it.
I'm just giving a pretty simplistic example. There are many different ways ground paths might be completed but this is the basic way it's done on cars and bikes. It eliminates a lot of extra wire and connection on one terminal of the battery.

Speaking of a path and HOW things go wrong, a common one is when people paint things and don't realize that the electrical path has been compromised because the paint is acting as a barrier keeping the metallic components from touching.

Example: Over the winter Johnny takes his bike apart to paint the engine and frame. The Battery ground or negative lead bolts to the frame. The positive lead goes to point of use like the ECM, ignition Switch, stater solenoid etc.

Before he painted it there was bare aluminum everywhere for the fasteners bolts, studs, and nuts to conduct, as well bare aluminum where the frame touched the the engine. The electrical path from the batteries negative lead to the frame and engine were intact.

After painting the frame and engine with acrylic enamel paint all of the points mentioned above, now have a layer of paint (plastic insulator if you will) between them and the batteries negative lead. Johnny bolts it all together and nothing electrical works except the the turn signals. WHY?

Well for one, the turn signals have a plastic body so they have their own wires directly to the energy source but things like the starters Ground Path now have plastic insulation between the main ground to the frame AND the Frame is also insulated from the engine by paint too.

Its why those star washers are used on bolts so they can cut and dig into the surface creating a path. Flat washes can leave the paint undisturbed and then there is no connection even though a bolt goes right into the parts (like voltage regulators etc.).

Painting CAN wreak havoc and you have to pay attention to HOW the energy is being transfered to complete a circuit. Usually there are separate ground wires to reach around the paint but sometimes people chuck them as they clutter the appearance and that's when things fail to work. Or simply stacking in the wrong washers placing the star washer against the nut followed by a flat washer. In this case, the star washer is needed to tear up the surface and make a connection.

Keep it in mind when you unbolt wires and components that touch the frame and engine.

WOW THAT got long. . .

Thank you Randy! Excellent! For those that are not familiar with 'Star Washers' They do to things. They act as a lock washer and have multiple biting edges that aggressively mate the two separate surfaces together. These are what you want for your electrical contacts.

Here's an example of one type of star washer: