Electrical Meltdown 1974 R75/6

[spencer_p]

… The Verdict, please !

The enricher cable going to the RH carb, was in hard contact with the RH coil casing; the casing is thoroughly grounded to the frame, a necessity for the primary & secondary windings. As time progressed, the outer sheathing of the enricher cable rubbed through to the steel spiral-wound support of the solid wire core, which is the actuating means for the enricher.

Un-fused 12VDC via a Red, 2.5 mm2 wire from the battery, branches to an un-fused Red, 1.5 mm2 wire at T30 on the connector board in the headlight nacelle. The un-fused Red, 1.5 mm2 then connects to the key switch T30 spade.

In all positions of the key switch other than OFF, un-fused 12VDC is supplied to the T15 spade at the key switch: a Green 1.5 mm2 wire. That 1.5 mm2 wire returns to the connector board and joins with another Green, 1.5 mm2 wire at the power side of the doubled T15 spades.

Still un-fused, the Green, 1.5 mm2 wire runs within the main wire loom to T15 on the LH coil. Also at the LH coil, T15, an un-fused(?) Green wire from the Enduralast system joins, for un-fused power.

In very close proximity to that Enduralast 12VDC, Green wire at T15 of the LH coil, is the Enduralast Brown, ground wire at the master chassis ground.

911 Operator: “Station 10, Engine 10-1, Rescue 10, Medic 12, Ambulance 14… a fire call; motorcycle smoking with possible fire; operator not, repeat not, injured at this time… SR 293 and I-495N… responding units use Fire Frequency 7 for comms.”

Engine 10-1: “responding and has command !”

911: “Engine 10-1 rolling and in command, all other units use Fire 7.”

Sorry guys… couldn’t resist

It appears to me, that a smaller short circuit occurred between the Enduralast Brown wire and the LH T15 multi-spade lugs ? Too small a wire to draw much current, just a little burn on the Brown wire insulation.

Things lit-off when the worn, fifty year old, Bowden steel sheath/wire of the RH enricher, provided a significant chassis ground, via the RH coil case ! The bridge wire between LH T1 to RH T15, does not appear harmed. I didn’t see evidence of the RH T1 making contact outside normal pathway. With such a monster ground, maximum current flowed in the Red and Green, un-fused ignition circuit, within wires not able to support the load.

I support BMW’s decision to not fuse the power feed to the stock ignition system. I’d rather two blown fuses and still be able to ride to a safe location.

Inattention to motorcycle maintenance: guilty as charged

Wow, alright that's pretty thorough! Are there any other components that might be compromised, which I should check in the process of the repair?

 

[olironrider]

Gee ‘Spence’… I figured you’d get a laugh outta the “Fire Call”: be pull’n on the bunkers & boots; be hittin’ the pole to the engine floor; grabbin’ the coat and “New Yorker” while heading for the tail-board

Well, the headlight nacelle is gonna have a lot of damage: key switch’s guts saw a lot of current; connector board in the back of the “Bucket-O-Snakes” warped; all the wire tangled with/near to the melted ones, will need looked at; of course, the main loom from stem to stern is junk ! I’m thinking the alternator, diode board under front cover should be OK but look for burn marks.

I’d be surprised if many light bulbs are still working.

If not already, have the Wiring Schematic in your Owner’s Manual enlarged to poster size, study it so you know what you’re doing and learn the wire sizes and color markings.

Don

 

[olironrider]

… another thing I noticed: Image 6919, the short wire bridge between LH coil, T1 and RH coil, T15 is looped down to very close proximity with the starter cover ! I’d suggest putting more space between it and the engine, which is grounded.

Remember that all the power for the coils, is in that wire and, you’ve had enough “Magic Smoke” under your Flammable Liquid Tank… can you say, B.L.E.V.E. ?

 

[spencer_p]

Gee ‘Spence’… I figured you’d get a laugh outta the “Fire Call”: be pull’n on the bunkers & boots; be hittin’ the pole to the engine floor; grabbin’ the coat and “New Yorker” while heading for the tail-board

Well, the headlight nacelle is gonna have a lot of damage: key switch’s guts saw a lot of current; connector board in the back of the “Bucket-O-Snakes” warped; all the wire tangled with/near to the melted ones, will need looked at; of course, the main loom from stem to stern is junk ! I’m thinking the alternator, diode board under front cover should be OK but look for burn marks.

I’d be surprised if many light bulbs are still working.

If not already, have the Wiring Schematic in your Owner’s Manual enlarged to poster size, study it so you know what you’re doing and learn the wire sizes and color markings.

Don

Haha sorry, I did appreciate it. I was just so overwhelmed that I didn't have the wherewithal to craft a worthy reply. Well done, Don.

 

[omega man]

This product has been mainly for the old English Bikes. May work for German bikes.
OM

 

[Lendog]

… The Verdict, please !

The enricher cable going to the RH carb, was in hard contact with the RH coil casing; the casing is thoroughly grounded to the frame, a necessity for the primary & secondary windings. As time progressed, the outer sheathing of the enricher cable rubbed through to the steel spiral-wound support of the solid wire core, which is the actuating means for the enricher.

Un-fused 12VDC via a Red, 2.5 mm2 wire from the battery, branches to an un-fused Red, 1.5 mm2 wire at T30 on the connector board in the headlight nacelle. The un-fused Red, 1.5 mm2 then connects to the key switch T30 spade.

In all positions of the key switch other than OFF, un-fused 12VDC is supplied to the T15 spade at the key switch: a Green 1.5 mm2 wire. That 1.5 mm2 wire returns to the connector board and joins with another Green, 1.5 mm2 wire at the power side of the doubled T15 spades.

Still un-fused, the Green, 1.5 mm2 wire runs within the main wire loom to T15 on the LH coil. Also at the LH coil, T15, an un-fused(?) Green wire from the Enduralast system joins, for un-fused power.

In very close proximity to that Enduralast 12VDC, Green wire at T15 of the LH coil, is the Enduralast Brown, ground wire at the master chassis ground.

911 Operator: “Station 10, Engine 10-1, Rescue 10, Medic 12, Ambulance 14… a fire call; motorcycle smoking with possible fire; operator not, repeat not, injured at this time… SR 293 and I-495N… responding units use Fire Frequency 7 for comms.”

Engine 10-1: “responding and has command !”

911: “Engine 10-1 rolling and in command, all other units use Fire 7.”

Sorry guys… couldn’t resist

It appears to me, that a smaller short circuit occurred between the Enduralast Brown wire and the LH T15 multi-spade lugs ? Too small a wire to draw much current, just a little burn on the Brown wire insulation.

Things lit-off when the worn, fifty year old, Bowden steel sheath/wire of the RH enricher, provided a significant chassis ground, via the RH coil case ! The bridge wire between LH T1 to RH T15, does not appear harmed. I didn’t see evidence of the RH T1 making contact outside normal pathway. With such a monster ground, maximum current flowed in the Red and Green, un-fused ignition circuit, within wires not able to support the load.

I support BMW’s decision to not fuse the power feed to the stock ignition system. I’d rather two blown fuses and still be able to ride to a safe location.

Inattention to motorcycle maintenance: guilty as charged

attention to routing is an example of the critical thinking process of the utmost importance when maintaining your own machine

 

[Lendog]

Wow, alright that's pretty thorough! Are there any other components that might be compromised, which I should check in the process of the repair?

Unfortunately it is possible that the alternator stator will be damaged

 

[stevenrankin]

FYI, EME sells perhaps the best wiring diagrams on the market. Large, plastic coated, in proper color with pins and terminal numbers. Beats the heck out of the ones in the various shop manuals. St.