R75/5 Electrical Q

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R75/5 Electrical Q

Post by p2squared » Mon Aug 28, 2017 12:49 pm

Was doing fine until…

Now, when key's inserted---no warning lights, no start, or horn. But the headlight will come on (if switched on w/key). High & low beam work, but nothing else.

Battery's good, charged, no corrosion on terminals.

Figuring fuse may be? Looking for direction to start in.

Thanks guys,


Kurt in S.A.
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Re: R75/5 Electrical Q

Post by Kurt in S.A. » Mon Aug 28, 2017 1:53 pm

Could be a fuse. Could be the starter relay.

Kurt in S.A.

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Re: R75/5 Electrical Q

Post by SteveD » Mon Aug 28, 2017 10:44 pm

Early /5 didn't have a fuse at all. Are the contacts in the switch good? That oem switch is old now and probably fragile.

I think the /5 wiring looms are still available and not too expensive. As an aside, after all these years if the bike was a keeper it might be a prudent long term purchase.
Cheers, Steve
Victoria, S.E.Oz.

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Re: R75/5 Electrical Q

Post by Wobbly » Tue Aug 29, 2017 10:11 pm

If the bike has sat unused for awhile, OR been washed with any type of soap... it might be a simple matter of corrosion on the brass switch contacts. I would definitely spray the switch mechanism down through the key hole, and from the inside of the headlamp shell with some type of contact cleaner before I jumped in to buying expensive harnesses and other repair parts.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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Re: R75/5 Electrical Q

Post by spo123 » Mon Dec 18, 2017 8:18 pm

Disconnect the ground first.
Then, spray a small bit of contact cleaner into and underneath the switch board assembly.
Use a tiny pair of hemostats and a bit of "scotch brite pad".....clean away and then "rinse" with wd40 or something.
You MAY also need to "tweak" the contact arm under the switch board, slightly.

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