Toast starter armature 1978 R100/7

[dkilmer]

I'm helping a friend with his 78 R100/7. His starter was not turning over so he replaced his starter relay with one from EME. Bike starter still didn't turn over. Starter relay "clicks" when start button is depressed. Suspected a bad solenoid but found it to be a bad armature. Ok. But why? The little black wire that operates the solenoid should only have power when start button is depressed. Well on this bike something is amiss as the wire has 12 volts as soon as the key is turned on. This seems to have caused the starter to turn when bike was running and kill the armature.

Any thoughts of where to start? He is bringing the original relay do we can check for any discrepancies. Any thoughts and ideas are appreciated.

[ME 109]

If the starter engaged while the engine was running, one hell of a racket would have resulted. your friend surely would have noticed?
Why would you suspect the armature to have been affected by the starter engaging?

We need Rob Frankham, GSPD, and a handfull of others but I can't put my finger on them...

[dwire]

This "sounds simple..." (Hello again crew here...) If in fact the "little black wire" was issuing 12VDC to the starter solenoid, it would not necessarily have had to made any major racket, for the inexperienced rider; save when the starter entirely came apart. With 12VDC applied to that wire, yes it is possible/likely that the armature is fried (considering from that moment on it continued to run at full speed of the ring gear on the bike - that's thousands of lifetimes depending how long this went on... Also likely the field has seen its day and sense a 10 mile ride with the starter engaged would have "overshot" the intended lifespan of the sintered bearings at either end of the starter, they are likely to be shot too.

Also things to think about, since this action was never intended, if the commutator is/was just the least bit out of round and the M/C was driven any amount of distance with the starter fully engaged (heaven forbid) both the brushes and I now cannot recall for sure how the "tiny Bosch's" brushes were fitted with regard to their backup springs and such, but if a pivotal mechanism was used (I don't recall this; thought the brushes moved inside their own square "tubes" on these with spring and contact) but what I am getting at is if there is any pivot point to back up the springs on those copper brushes, they are likely trashed too. Could have even been worn entirely though depending how long this went on.

What might have caused this? Lots of things could have been the failure mode - #1 is it is a 30+ year M/C that has likely seen NO starter service in that time. The solenoid could have merely stuck "closed" due to grease, oil and "yuck." Also the handlebar switches on these can get their hair like weak wires crossed - contacts in those switches can cause issues too.

And of course we come to the start lockout relay that could have gone haywire. Do you know if anyone ever performed the update to that can? was it done correctly?

At any rate, unless you can see the black windings or are able to measure near zero resistance across multiple adjacent sections of the armature, I would take it to an armature or starter/generator shop and have it fully tested. My intuition tells me, look for a serviceable unit on ePray and find the root cause; either within the junk one you are pulling off or in the bike itself. Could be a simple short one may find with a 2$ meter; could be more complex too.. In general we need more info to know how to help you best.

You can know if the armature truly is bad with one of these; (below) not sure how many shops around have them. Not super useful for windings really; best bet is a hi-pot tester - something a gen/alternator/ armature shop would have handy...



There are several online walk through's of rebuilds on the web here - most done by members here. Most are done rather well. BUT most only cover rebuilding your starter, not diagnosing the electrical system to the low current solenoid actuation wire from the loom...

I have at least one perhaps two of these starters that will be rebuilt for spares and documented for your enjoyment. Though this does not help your friend today and I'll need to dig for them as I've been unable to find anything but my spare R75/5 tranny as of yet.

Best of luck - the more details you post, the easier it is for the nice folks here to walk you through a logical test procedure to get rid of the 12VDC on the solenoid wire - THEN and only THEN is it time to worry about the starter as new or rebuilt one would fail identically.

[dkilmer]

I am not certain if the starter was in fact running when bike was running, I was not the one operating it so I cannot confirm, but with a constant 12 volt supply one would specualte that is how it was burned open. I secured another relay and yup still 12 volts constant on the little black solenoid wire with key on. Going to trace wires out of relay and try to see where that solenoid wire comes from in fact, I did read R. Fleischer's article on starters and am curious about the headlight relay diode,
I am going to also remove my personal bikes starter cover tonight to check on the voltage status of the solenoid wire voltage.

[dwire]

I re-read your post above. This sounds pretty straight forward other than what was mentioned by ME 109 and you did not need any of the crap I posted as you fellas already bought a new starter, so no matter what the failure was even if it was not in the starter which is likely it was not, it is irrelevant now. Look for the starter actuation lock-out relay - I know zero about bikes that old (meaning newer than mine) a 71, but this should be easy.

Where is the click coming from? Under the tank up by the handlebars or on the frame there or under the shroud on top of this new starter where the solenoid is located that was purchased? Believe you me, if the original starter never dis-engaged as is lamented above, no one would "not notice that" and burn up their starter. EVEN WITH the gear reduction between the teeth of the flywheels ring gear and the end of the starters Bendix gear, you'd have to be deaf to be unaware the motor was continually running the starter. Also, don't count out that a bad relay can not allow enough current through to actuate the solenoid fully, or at all, so listen both places. I won't get into how to do these things with meters and such as frankly I don't think at this point it need get that complex...

I can only guess as most here, I'll take them in order.

1) Starter engagement protection lock-out relay is bad - carefully fix it. Instructions I think you already found. 5 minute fix; one will spend more time carefully prying the relay open and carefully pinching it back together than ever making the modification...
2) Short circuit. (seems unlikely, but anything is possible - how old are these bikes?)
3) Bad starter switch which likely should be #2...
4) Bad brand new starter or wrong one...

I hope for yours and his sake you did not give anyone that bad starter. Unless you opened it up and saw melted copper from the brushes, commutator totally ruined and charred lacquer on the armature windings and stinky fried field windings- it is very possible there is nothing at all wrong with it. Worse case if it is in the "starter to a degree" it is the solenoid, easily had, replaced or my preference unless melted repaired (but they are figety without the right tools...)

Finally, "click, click" OK where is the click click coming from??? The relay that is supposed to keep the starter from being able to be engaged while driving down the road (or at least once the "generator" (alternator) light is out, or from the solenoid on the starter. Even if it is from the starter, are you sure you have the right one? wrong tooth count and they will do more than click, but if the flywheel and starter are aligned just right, it can get "hung up" and all you "might hear" is the solenoid trying to do it's job; and it never gets far enough forward to make the contacts of the starter close (likely a lucky thing...)

To me, this should be easy - find the click. I'd bet you find it in the relay on the bike and not at all have beans to do with the starter. Or the wires have just had it i the switch if they are designed as mine are and one of the two (brown I think) wires are just holding on by one strand... Find the click and you will find your answer. Report back to us. If and when you do, if there is still a fault in the system, please both keep track of what you did and found and in what order you did them. It is very hard to be helpful when it is unclear what has and as not been done if that makes sense...

If the OEM starter was not turned in for a core and you find it not to be a problem, I love spares... lol Just so long as it would properly fit my '71 R75/5 and I am thinking from here and elsewhere - would have to look sadly it may be the wrong tooth count - not sure though... If the owner cored an electromagnetic fielded Bosch starter for a Valeo, I do feel bad for him. I know everyone says they got the issues fixed with the bad glue and falling out permanent magnets and such, but I have a 53 Chevy out here with OEM starter that has been sitting on the ground basically that would fire up anything you put it in, so by all means the original Bosch design was not a bad one and they were just miniaturized versions of what was on that car.

I think you will find this fix to be far easier than when you began. The common failure mode on starters; aside from solenoids, which both Ford with their outboards and GM with their DELCO on starter type that many miss and let go forever are the front and rear sintered bearings The front nosecone and rear sintered bearings wear out until one has the armature rubbing on the inside of the field. These starters with armatures dragging their fields are prone to all different failures from there out, but many owners miss this for years - until they have replaced all the battery cables and put the filth battery in, because their engine will not start and turns over even with their new battery as if it is dead... I actually learned this lesson as a young teenager right before going to work for the Auto biz. I never forgot it ether...

The start protection relay seems to be a pretty popular failure mode for our BMW bikes - a failure before ever issuing current to the starter...

[dwire]

EDIT --> ADD WARN OUT CONTACTS IN THE RIGHT HAND SWITCH AS WELL I HAD A CLICKING NO STARTER FOR SOME TIME UNTIL I COULD GET A REPLACEMENT SWITCH FOR WHICH SOMEONE DOING A CONCOURSE RESTO WAS KIND ENOUGH TO DONATE THEIR PERFECTLY WORKING ONE TO ME FOR THE CAUSE

Have you been by Duane Ausherman's site, or any of the many other informative sites all over the net that have wiring diagrams and schematics for these old bikes? With your troubles, that is where you should start; type in 1978 r100/7 schematic then perhaps wiring diagram. If the listing is for eBay, skip it as there are free resources out there and these people for the most part are simply making a living off of someone else's work - YES even if they have re-drawn it; don't get me started, I have been making a living for a long time on intellectual property... (Wish that stuff came in forever and I would be set) but such is life one must move forward and improvise sometimes.

Please let us know about your progress. A giant odd failure is just as important for the users here to know about as a silly mistake is. Read all around the forum. Don't be bashful if there is/was some human error involved; a great deal of the posts here and as well lessons in life are learned that way - no one is going to make fun of you, hopefully they will renumber this so next time it does not happen to them.

In fact I am just going to update a nearly two year old thread as soon as I submit this. The problem was determined and it was human error and MY fault, but if that saves one person from doing what I did - that makes it all worth while. In these instances I have no such thing as pride to stop me from hopefully helping others, that is just silly.

[dwire]

Did we ever come to the bottom of this mystery? I mean, this stuff is like a soap opera and all; you're not pulling a "to be continued..." on the forum are you? Inquiring minds want to know...

[Major Softie]

Did we ever come to the bottom of this mystery? I mean, this stuff is like a soap opera and all; you're not pulling a "to be continued..." on the forum are you? Inquiring minds want to know...

Wow! You got mysteries, serials, soap operas, and the Enquirer - all in two short lines!


you rock

[dkilmer]

Update. I have not had too much time to inspect wiring but I did come closer. The starter relay and start switch all function properly. What I discovered is somehow headlight power is feeding the start relay black wire, which is the culprit that killed the starter. This particular bike has the function when you activate the starter it kills the headlight. Coming off the relay piggybacked with the solenoid black wire is another black wire headed to the headlight relay. When I disconnected that wire from the headlight relay the solenoid wire lost its constant 12volts. I then depressed the starter button and it operated normally. Now to figure out why the backfeed of power.

[dwire]

Update. I have not had too much time to inspect wiring but I did come closer. The starter relay and start switch all function properly. What I discovered is somehow headlight power is feeding the start relay black wire, which is the culprit that killed the starter. This particular bike has the function when you activate the starter it kills the headlight. Coming off the relay piggybacked with the solenoid black wire is another black wire headed to the headlight relay. When I disconnected that wire from the headlight relay the solenoid wire lost its constant 12volts. I then depressed the starter button and it operated normally. Now to figure out why the backfeed of power.

Sounds like a good start. Interlock stuff like that can be a PITA, but the circuit you are describing at least sounds pretty straight forward. Let us know and I'd likely want to assess the original starter before giving it away as a core or anything for a different starter if that has not already been done; considering you don't know for certain what happened, I think that would be prudent. I'm only knowledgeable with the Bosche units, but to my knowledge the only real difference would be their substitution of permanent magnets for energized field windings which is how the Bosche's were designed...

Thanks for the update, apprise us of your progress; sounds like a simple fix from my end - but then again, I am not standing on my head looking at the spaghetti mess inside of a headlight bucket! Could simply be the wiring is reversed at the interlock relay or headlight; neither device would care, but the starter sure would...