General Category > General Discussion
1975 850T electric mistery
cliffrod:
--- Quote from: n3303j on July 19, 2026, 09:04:43 AM ---Pull them apart. Clean them thoroughly. Grease them up. Reassemble.
Had recent problem with headlight shell ground on the T3 (after installing excellent Bender harness). There is a ground tab riveted to the shell. Turns out 50 years of corrosion in that area insulated the tab from the shell. Drill out rivet, clean all metal parts thoroughly, pack assembly with grease then re-rivet and all problems went away.
--- End quote ---
This^^^^ is what can happen with any and potentially all of the riveted connections on these old bikes. My original fuse panel looked great with no undue or obvious corrosion issues. After checking continuity and drilling out rivets, the hidden corrosion on every connection was impressive. Lots of small losses created the larger cumulative problem.
cappisj1:
I had a pin break inside one of the headlight pugs. Took a summer and a half to find it. That caused my T to immediately lose power to the engine. From rumbling down the road to instant dead silence coasting down the road. I don’t envy your future of tracing wires.
chuck peterson:
Moto Guzzi, making electricians out of motorcycle riders since 1921…
Similar situation…dead everything with the key on
Opened the fuse block, spun the fuses in their settings, started right up
Corrosion
Also…
Check both ends of the battery neg ground cable, and up inside behind the sheathing, then scrape, sand and smear the frame. It only happens because it’s a 50 year old bike. Do the same for all your grounds…add a second ground off the diode board to the engine bolt holding the transmission on…
Stretch:
There is nothing - but nothing - harder to troubleshoot than in intermittent
electrical fault!
-Stretch
wirespokes:
That's why I solder connections, like those riveted, or wire ends.
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