How does engine ground to frame

[nezzer]

I am doing some troubleshooting on my bike after lots of parts swaps. I am curious about something, what is the primary method that the engine is grounded back to the frame? I am having some issues starting the bike and I am thinking this may be the culprit.

Is it grounded simply by the engine mounting bolts? Is there supposed to be some a wire connecting the engine to the frame?

Thanks.

 

[shotgunjoe]

Direct metal to metal contact through the motor mounts is sufficient. Theres more fround contact on these than most cars.

 

[gggGary]

The late model bikes have ground wires on the head mount bolts. (two on a lot of them) Our engines are not rubber mounted so they probably are not as critical as they are on a car.

 

[nezzer]

makes sense. Thanks.

 

[Gordon]

Nezzer,
The engine is suppose to ground through the frame by directly bolting to it, but, I had trouble in this area. My '80 G model would not charge correctly, which resulted in burning up 3 rotors. seem's that the frame was not grounging enough. How I found this was a pure fluke. The battery's are very small, so for trouble-shooting, I used a car battery with jumper cables. I used different spot's to clamp the cables onto the bike. The last time, when I found the bad ground, I had the cables mounted one on the positive side of the battery, and the negative on the frame. I had my volt meter on and started the bike. The voltage was good and steady. Removed the cable's and the voltage started to jump around allot. Put the cables back on, nice, steady readings again. So I took one end of the neg. cable, went from the neg. terminal on the battery( in the bike) and then to the engine, right on the cam chain adjuster. Bingo! Nice, steady reading's. So I took a 6 gauge wire( an old jump box cable)and mounted one end to the engine on one of the cam chain adjuster bolt's, and the other end on the frame where the negative cable connects. That was 4 years ago, and no more charging problem's.

 

[pumps]

On my 77 there is a ground wire from the mounting bracket on the top of the cylinder head to the part that bolts to the frame under the tank.

 

[weekendrider]

Hope this helps neezer. The ground wire (as supplied at the factory) goes under the mount on the right side(front bolt hole) to the inside of the top left piece where it attachs with a phillps screw. Clear as mud I'm sure.
Sorry I could only locate the pic of the motorside. So if you have a double eyelet wire about 6 inchs long with a 1/4" hole in one end and 7/16" on the other this may be where you want to put it.

Ahh while I wonder around the pic album, Pumps has the answer.
Long time no see Pumps. Hope and yours are doing well

 

[Tech7]

If you think it is a problem, just add another wire from the frame to the engine in a nice clean spot. You can't have too much ground. If you've got a lot of paint on the engine or frame, you might have a bad connection.

 

[shotgunjoe]

If you think it is a problem, just add another wire from the frame to the engine in a nice clean spot. You can't have too much ground. If you've got a lot of paint on the engine or frame, you might have a bad connection.

Very good clarification. Paint and dirty/corroded threads always cause grounding issues. I have fixed 100s of ground issues by simply giving good contact path between ground points, and even removed PO 'extra' wires for cleanliness.

If your like me and hate to see wires out in the open on your bike, use one of those short braided grounding straps hidden under the tank from the top of the head to the coil mount. Be sure your connections are CLEAN, use dialectic grease to keep them from further corrosion.

(I have a habit of understating, and leaving out details unless probed further)

 

[XSLeo]

What I've done is take one side of the top mount off, take it apart. Wire brush all contact points in the mount and where the mount touches the head and frame. Put some dialectric grease on all the contact points to prevent corrosion. Reassemble. Good to go.
Leo