Non-GS Earthing of coil

[The Other PaulG]

Sorry it's non-GS, but I might just lose my sanity if I don't get my DR600 functioning soon...

My question - On my DR600 there is no apparent way that the coil earths to the frame.

The coil has the two LT leads coming in, and 2 x HT lead outputs. There is no visible way that through its mounting bolts, for instance, the coil earths itself to the frame. So, how does the HT circuit complete? Does one HT lead act as the earth for the other?

My symptoms, by the way, are an extremely weak spark. I have had electrex check out both the coil and the stator/trigger windings and resistances.

Help?

Paul G
The other

 

[wessie]

This picture shows a typical auto-ignition system with condenser-points rather than electronic ignition. Note there are 4 spark plugs in this particular example.

The coil has 4 connections just like yours.

This page explains how it works: the "coil" is actually 2 coils which form a step-up transformer.
http://www.procarcare.com/icarumba/...icar_resourcecenter_encyclopedia_ignition.asp

If you are not getting a spark then the most likely faults are in order of likelihood:
1. wiring: including a poor earth from engine to battery
2. condenser
3. open circuit in one of the coils - check with a meter, but you'll need the resistance values from a workshop manual
4. short circuit in the coil - check each winding for a short to ground, a short across the coil or a short from one coil to the other

 

[The Other PaulG]

Thanks, I'll re-check those items you mention.

I'm still a bit confused though, because the wiring diagram clearly shows a complete circuit (except for the gap at the plug electrode) on the HT side.

If my coil isn't obviously earthed, how is my HT circuit completing?

Paul G

 

[The Other PaulG]

More info

Sorry guys, I should provide a bit more info:

The DR600 is a sigle cylinder thumper, with a twin-spark head. It runs a 12v electrical system which is a bit unusual in that the ignition circuit doesn't take any charge from the battery - it all comes direct from the flywheel.

I think I'm right in saying that bikes like this can in theory run without a battery (although with perhaps a resistor in the battery's place).

It has a cdi box, as opposed to points. The coil is a single unit, with two HT leads.

PG

 

[Greg Masters]

I think Paul's issue with this is the existence of the wire shown in red - he hasn't got the option of that on his coil.

However, some Jap bikes fired when the points closed (not when they opened) and use a different type of circuitary.

It's possible that yours is one of these and that the HT side of the coil earths internally.

Greg

 

[The Other PaulG]

Yep, that's exactly my problem Greg.

I'm wondering whether I should take another 12v coil, with a traditional earth, and briefly try that??

 

[Tarka]

You`re confusing yourself and possibly everyone a bit here....going from asking how the coil is earthed to asking how the HT circuit is earthed....

The LT circuit is seperate from the HT circuit....

The coil has the two LT leads coming in, and 2 x HT lead outputs. There is no visible way that through its mounting bolts, for instance, the coil earths itself to the frame.

One of the coil`s two LT leads goes to earth...

So, how does the HT circuit complete? Does one HT lead act as the earth for the other?

The HT circuit goes to earth via the spark plug....across the electrode gap.

That`s how the spark is created.

 

[The Other PaulG]

Thanks Tarka

Sorry if I'm being a bit dim...

I'm happy with the route the HT charge taks from one end of the HT coil through the HT lead, across the plug and to earth (the engine block), but what about the other end of the HT winding, doesn't that also have to earth in order to complete the circuit?

PG

 

[Tarka]

but what about the other end of the HT winding, doesn't that also have to earth in order to complete the circuit?

It`s an internal connection....as in a 'centre tap' transformer.

If both the LT and HT circuits had their own individual earths that would be an 'isolating transformer'.



Have you checked the killswitch circuit and sidestand cutout switch (if fitted) ?

Have you tried new plugs of the correct grade and with correct gaps ??

Have you tried chopping about 6mm off the end of the HT leads and new plug caps ??

Is the stator plate earthed properly ??

Is there a good earth strap from the engine to the frame ??