1978 r100rs - won't start after hibernation

J

jsey

New member

• May 13, 2023

• #1

Put the bike away for the winter in nov and just pulled it out no juice to the starter. Battery fully charged and everything but the starter works. Pulled the starter cover off and cleaned all connections. Power is coming to the large cable. When i test the small red cable no power when i press the starter button. I'm about to trace that. Looks like it may head towards the alternator chest. In the meantime anybody have any ideas? Thanks

 

6322

Member

• May 13, 2023

• #2

Check all of your connections, particularly grounds, all clean and tight. May be related to the starter relay?

 

20774

Liaison

Staff member

• May 13, 2023

• #3

I agree...check the easy stuff first. Unplug/replug the starter relay a few times to clean up any corrosion. What does the battery voltage say when you push the starter button? If it doesn't change much from nominal...say 12.5v...then the relay is not kicking in.

I'm going to add more context to the thread title.

 

J

jsey

New member

• May 13, 2023

• #4

Thanks guys. Where is that relay located? I didn't think that was my thread title.....But I like it! Thanks again

 

pglaves

#13338

• May 13, 2023

• #5

If the solenoid engages but the starter motor fails to turn you will hear a clank but not much else. In this case it is the contacts in the solenoid or a starter motor issue.

But if you don't hear a clank then the solenoid is not engaging, so you need to test and trace the small wire to the solenoid back to the starter button.

 

J

jsey

New member

• May 13, 2023

• #6

Ok. Nothing but silence. Is the starter relay one of the two relays mounted and located just under the front brake master cylinder?

 

Omega Man

Fortis Fortuna Adiuvat

Staff member

• May 13, 2023

• #7

How old is the battery? Sometimes “fully charged” batteries only have a “surface” charge that look good but have nothing behind them.
OM

 

20774

Liaison

Staff member

• May 13, 2023

• #8

The relay is one of these two on the left side of the frame backbone under the tank. See this post:

https://forums.bmwmoa.org/showthrea...-Horn-wiring&p=1198091&viewfull=1#post1198091

 

melville

Member

• May 13, 2023

• #9

Yes, the starter relay is the rearmost one on the left side of the frame under the master cylinder. On my own /7, it was the weak link as I was reviving it after it sat for over 30 years. Pulling it and cleaning up the connections was essential.