Episode of Starter Running

The other day, I started my 1988 R100 RS and the starter motor kept whirring. It was not engaged with the flywheel. There was just the sound of the motor spinning. In shutting off the

engine, the motor continued to whir. While it whirred, I popped up the seat and removed the tank, lickety split. Pulled the starter relay and it kept on whirring. Put the tank back on and

just hit the road. In less than the distance of a city block, the starter motor ceased whirring on its own and I rode home. The only thing I noticed was that the amp meter showed a

depleted charge in the <12V range. It is my guess that the spinning starter consumed a bunch of juice.

This happened a month or so ago and my first inclination was to replace the starter relay. As it has not been replace in 31 years, I figured it was an extravagance that was deserved. A

used starter relay came with some other stuff I bought a few years ago and that used one was the replacement.

Does it not seem odd that removing the starter relay would have no affect on the starter motor spinning? Any ideas what I may be up against?

Does seem strange. Hopefully you did remove the right relay...I thought there were several mostly the same. Have you been able to recreate the situation? Sounds like the motor was running but the solenoid which actuates the Bendix drive wasn't actually working.

Your starter solenoid does 2 things when activated by the starter relay.
1) Engages the starter drive with an electro-magnetic actuation.
2) links the starter drive motor to the battery.
This high current activity is provided battery current thru the big wire direct from the battery. The solenoid is only a control gate that works under the direction of the starter relay.

20774 said:

Does seem strange. Hopefully you did remove the right relay...

Click to expand...

Yes, I have the wiring diagram and I know how to use it.

[/QUOTE]I thought there were several mostly the same. Have you been able to recreate the situation?[/QUOTE] Only when I try starting it. However, it's only done it twice.

[/QUOTE]Sounds like the motor was running but the solenoid which actuates the Bendix drive wasn't actually working.[/QUOTE] Indeed, it does seem that the motor is running without the Bendix engaging.

Thought that I'd report back my findings. Went out ton start the bike this morning and the starter motor continued to whir. That made me think it must be shot. There was an old

Bosch unit on a shelf that I somehow managed to finally get wedged into the space where starters go. Gave the starter button a push and low and behold, it works. It was a Valeo

that I must have put in 14 years ago. When I looked at the price of rebuild components versus buying a new one, it's obvious that they want to buy a new one and not dick

around with rebuilds.


The weather has been pretty rainy here the last several days which caused me to close the garage door. This slightly darkened space then revealed to me that the coil is arcing.

Oh well, what can be expected after all these years and miles.

Nice trouble shooting!

There is a large solenoid on the starter with a plunger in it. It's enabled by the relay.
The solenoid gets full of carbon dust from the brushes and eventually it will stick and not release. You witnessed the result of this.