Hey Guys, Need some diagnostic help please. Have put my bike back together and have run a couple of short test rides. (Rehab was all fuel related and pulled out old radio and radar detector, replaced other fluids) Thought I heard an electrical arcing noise? from the instrument cluster. Bike would not start last time, fouling plugs (wet). Checked coils and connections--ok. Lifted tank up to look for loose connectors and bike starts when tank is ajar. Arcing was louder and thought I saw spark from frame to tank. Place tank down on frame and bike wants to stall. Looking at previous posts, I'm suspicious of a loose earth (ground in u.s.) I do not see one from starter, as mentioned in past, or one from the tank as mentioned earlier. Inge, do you have a schematic of all earths that should be present on bike manu 10/84? Any other ideas would be great help...I'm diagnostically "challenged" when comes to electrical faults. Thank you, keith

The starter is earthed using the chassis or it will have a large cable going from the battery negative to one of the 2 bolts holding the starter to the gearbox.

most of the electrical connectors run there earths back to the main earth point on the center of the frame, where they all connect to one point. It may be worth removing them there and cleaning them all up.

It does sound as if when the tank is in place that it is pushing down on a connector or a loose wire is touching the tank to cause a spark type effect....

Does the instrument cluster operate correctly as that is where you thought you heard the spark coming from.... The main connector to the instrument panel is part of the main wiring loom once it enters the bike's frame it passes the ignition controller thingy... (grey box at the top) and then you will find all the other connectors...

"deoxit " is your friend ....

it is quite common on "new to us" bikes, that many some or all the electrics should be cleaned and de corroded , this goes particuarly for under tank connections , which often have laid dormant and corroding away in adverse atmoshperes ....

in many cases ...modifications have taken place by previous owners ...which will be a mind bender at a minimum.

some benchmark important connections are located under the tank including the main electronic component earths ....to the centre rib of the frame .

take care and photograph everything that you do .....you may find that there is a connection or two in need of a cleanup at a minimum ....electrickey will flow along copper and brass etc ...but green corrosion is beyond normal and highly unpredictable .

this "deoxit" that we speak of, is a treatment to restore conductivity across those electrical plugs sockets and terminals ...it will not replace missing copper, nor is a magic formular ...you may find it in "pro music shops" , as the intended purpose is to eliminate electrical buzzes and humms for musicians equipment leads .

hope this helps some ....there are quite a few recomendations for this product across the forum

Thanks Charlie, That is helpful for sure....The starter would be grounded at chassis. I will double check all earth connections I can find. . Yes the instrument panel is normal and I pulled the fuse for it to check and the arcing continued..I am worried about the ignition control. Deoxit is a common product for you guys, I use an anti-corrosive gel in my work connecting aluminum to copper house wires, I think it would be similar. The bike has 12k miles, pretty much original and has been in garage storage since new, so there is very little oxidation or corrosion on any of the parts. There was no earth connection to the tank when I pulled it originally, and only wires I have suspect about are the leads to the fuel pump but find no damage to them...

yeah that gell does the job ......but i might propose that it is an air exclusion device ...ie no oxidisation without oxygen ....blah blah ....which is great for "new terminations "

the deoxit is an acid in stucture (probably phosphoric ) with a suporting formula for stability and lubrication of the electrical connection ......dont forget there could be microscopic pitting that may have developed (electrolysis) from metals under the influence of dc voltage .

but you already knew that huh ?

Nope, all new stuff to me Charlie... I will look for deoxit or similar (nephew is professional musician, might be easy to get). is it a liquid, paste or other. Thanks

Thanks Twincarb too!!! I should pay more attention ...sorry.

...thanks Charlie

when i restored my k100, i had to totally unwrap the entire wiring loom to cure 'black wire' syndrome, ( where moisture has travelled inside the wiring between conductor and insulator) . I was horrified to find that the wiring loom was manufactured with many bare wire , twisted connections inside, wrapped into the cloth outer insulation. these connections were cases were multiple wires were common, for example earths, and common live feeds to various items. I soldered all these connections, and applied heatshrink over them. The entire loom was then wrapped in high quality insulation tape and protective spiral wrap. In damp conditions, i believe it's possible that insulation faults in the wiring can track along the old cloth cover.

youre right sven ....its called capilarary action , usually happens when there is differences in temperatures between hot and cold , ingress of water and over heating action at a certain connector (usually caused by some corrosion of the local connector , ...i have seen it travel many metres along high quality cables and start corrosion over time and the old "k" bikes, are prone like many others, to this intersting occurence .

the only fix that i have been able to achieve is to douse the end in some phosporic acid ...which will clean off the oxide completly ...but only locally ...ready for soldering ....but soldering has its demerits in a vibrating situation .(like on motor bikes ) .the joints tend to break over time , like all automotive applications .

best, if you can, is to replace the cable completly as the corrosion cannot be contained in such wet enviroments .