Boxerworks.com

Hello,
I have a 78 R100/7 and in the past I have noticed that (sometimes) when starting the starter will try to spin put "freezes" and will spin up on second try. Now all I get when trying to start is very rapid loud clicking from solenoid. The starter does not turn at all.
I have cleaned all battery, starter, and starter relay contacts. Same issue. I hooked my large battery charger and set to 12V 10 amp. Same issue. increased battery charger to 12V 40 amp only for as long as I tried to start the bike. Same issue. Rapid clicking only.
I believe this is an original Bosch starter. (looks quite old) I've had the bike for 3 years, and have no idea whether or not the starter has ever been serviced.
My next plan is to pull the starter and inspect for anything out of the ordinary.
Any ideas on what to try next?
Thanks.
-Chris

Chris, the Bosch starters on airheads are a known weak link. As you describe it the problem sounds like the nose bushing may be worn. They can be replaced if you are confident in your mechanical skills. Another common problem is that the magnets in the starters are glued to the casing and they can come loose and jam the starter. Rick Jones at MotorradElektrik in Alabama, http://www.motoelekt.com/, does a fine job rebuilding BMW starters, or you can replace it completely with the lighter Nippondenso, a bit pricey though.

I thought the Bosch starters didn't have the glued magnets, that was the early Valeo starters.

Before you pull the starter, confirm that power is going to the starter solenoid from the relay when you push the start button. Just hook a trouble light to the female end of the wire that attaches to the starter. If you do get power that far, you know your starter switch and relay are doing their job.

To test the starter itself, you can jump from the battery cable terminal on the main part of the starter over to that solenoid terminal, and the starter should turn over. If it doesn't then you can pull the starter and try to fix it.