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BMW Motorcycles (aka Beemers) and the Competition
Have an interest in BMW motorcycles or just motorcycles in general? Discuss the line of BMW motorcycles and how they may compare to the rest of the competition in this forum!

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Old 12-16-2009, 12:57 PM
tingleplate tingleplate is offline
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Location: surrey
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Mein Auto: rs100

Where is the starter motor relay situated on a 1981 r100rs twin . I have removed the petrol tank but can`t find it underneath. Can anyone help me please?
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Old 12-17-2009, 06:57 AM
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mullman mullman is offline
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Mein Auto: '09 MINI, '09 HD, '67 BMW
IIRC, there should be two relays under the tank (one being the starter).

The previous owner(s) could have moved it, so trace it down by following the wires from the switch or the starter motor.

Some info here:


Otherwise two forums covering Airheads of that period:

Boxerworks forum
ADV Rider Old School forum

Here is a late 78' R100S schematic, should be pretty similar:


'09 MINI S: 'Ronin' '09 H-D Nightster '67 R60/2+'52 Steib sidecar
•previous '95 318i '00 540i6 '61 R50S '69 R69US '98 R1100R '65 R50/2 '64 R50/2 '07 BMW 530i6 ED

Last edited by mullman; 12-17-2009 at 07:08 AM.
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