Coil mounting/grounding

[Pendulum]

Do the coils ground via the mounting studs on the '77-'79 GS550? I ordered some Emgo coils that are supposed to be OEM replacement but they don't line up 100% correct. I can make them work, but they won't be mounted via metal screws to the frame anymore.

[azr]

Yes........

[niclpnut]

Set of dyna coils a buddy had didn't fit. Got it tightened down through one of the posts, zip tied the loose end of the coil to the frame and ran a short ground wire from the other post to the other frame mount.

Nic

[Pendulum]

Set of dyna coils a buddy had didn't fit. Got it tightened down through one of the posts, zip tied the loose end of the coil to the frame and ran a short ground wire from the other post to the other frame mount.

Nic

My solution involved some zip ties and nylon spacers. I'll just run some ground wires to the posts.

Thanks guys.

[hikermikem]

Hmmmmm.... seems like I've mounted dyna coils without any regard what so ever for a ground - just ziptied them to the frame.

I thought the 2 wires running to each coil was enough; isn't one of those a ground from the the sig gen, the other 12V ?

Never had a problem.

[Pendulum]

Hmmmmm.... seems like I've mounted dyna coils without any regard what so ever for a ground - just ziptied them to the frame.

I thought the 2 wires running to each coil was enough; isn't one of those a ground from the the sig gen, the other 12V ?

Never had a problem.

That's what I assumed too, but I'm having some starting issues and I got to thinking that the coils may not be getting a good enough ground. Hence this thread.

[hikermikem]

That's what I assumed too, but I'm having some starting issues and I got to thinking that the coils may not be getting a good enough ground. Hence this thread.

Double check you got the correct wires (right/left) feeding the correct coil. Some yahoo who looks very much like me has made this mistake before... or, make sure the correct coil is feeding the proper cylinders; again, that same yahoo has discovered this error a time or two.

Check you have good spark through each plug wire by attaching a plug one-at-a-time to each plug wire & lay it (ground it) against the head while you turn the engine over - those dyna coils should give you a nice blue spark.

Of course we are assuming you have a solid 12+V at the coils - check that as well with a multimeter, you may have to manually turn the engine over to get the sig gen in the right spot to "connect" to each coil.

[mike_of_bbg]

The primary grounds through the wires to the points. The points charge the isolated primary coils by providing ground, then cause them to spark by pulling that ground. The secondary needs to jump it's potential across the plug gaps to the motor ground. I can't see where the coils would need a constant ground contact at all??? Perhaps someone will correct me?

[Pendulum]

Double check you got the correct wires (right/left) feeding the correct coil. Some yahoo who looks very much like me has made this mistake before... or, make sure the correct coil is feeding the proper cylinders; again, that same yahoo has discovered this error a time or two.

Check you have good spark through each plug wire by attaching a plug one-at-a-time to each plug wire & lay it (ground it) against the head while you turn the engine over - those dyna coils should give you a nice blue spark.

Of course we are assuming you have a solid 12+V at the coils - check that as well with a multimeter, you may have to manually turn the engine over to get the sig gen in the right spot to "connect" to each coil.

Done all that, while the bike was cold... The problem is that it won't start when hot. I just recently rebuilt the carbs (properly, w/ berrymans and o-rings) and added K&N pods (airbox was on its last leg. I've added bigger mains and adjusted the needles). I'm also running straight pipes until I can get my new exhaust built. Stock one was junk. I've got new mufflers, just need to get my buddy to weld them up. So with all these changes happening at once, I've got a few areas to look at. I'm thinking it's a fuel issue rather than spark, but it occurred to me that the coils MAY need those bolts as grounds.

The primary grounds through the wires to the points. The points charge the isolated primary coils by providing ground, then cause them to spark by pulling that ground. The secondary needs to jump it's potential across the plug gaps to the motor ground. I can't see where the coils would need a constant ground contact at all??? Perhaps someone will correct me?

That was my thinking as well, but I also thought that maybe if the ground wasn't that great, once the coils got hot the resistance would be enough to prevent me from getting the bike started. I haven't had a chance to test for spark when it's hot. The only time it wouldn't start was at a gas station and I didn't have any tools.