Hello,
I've a problem with strating my Bike.
Yesterday i replaced the starter motor brushes on my 86' K100 RT,fiiting the new brushes was kind of a hassle,
I coldn't get the bottom part correctly on the housing.
Apperntly you have to twist teh two part on to each other, but in my case the brush plate was twisted as well.
Covering the screw hole in teh bottom part.
After a lot of fiddling around i manage to get all part toghterhe again. ;-)
After i placed the startmotor back in to the housing and reconnected all cables., i try to start the engine,
I only heard starter motor spin, but it wouldn't engage .
The sprag clutch was recently replaced and was working fine up until yesterday after the brush replacement.
Couls it be that the starter motor is rotating in the wrong direction?
If so, how can i test this and how can i make it rotate in teh correct directing?
Any advice is highly appriciated...
KR,

Amster.

Did you get the correct brush plate because there are many different plates and only the BMW plates have the brushes in the correct polarity. If you got the wrong plate the starter will be spinning backwards.

Hello Rick G,
I ordered Brush Holder plate #12411459297.
It looked the same as the old one.
The strange thing was that the bottom cover and the housing where hard to allign whitout covering the screw hole with the Brush Holder Plate.
(on the side with the smaller cutout, one side of the plate with the larger cutout there was no problem)

It sounds like the sprag clutch is stocked.
Before taking the starter apart, put your bike in 4th gear, rock the rear wheel back and forth. Then try the starter again.

Most of the time this will temporary solve the problem.

CF

It is very obvious if it is the wrong plate, the brushes sit in a 90deg and they are just opposite, very easy to see so I would say you have the correct plate. Try putting it in 5th gear and rock the bike back and forth to see if the sprag clutch will grab.

I'll try to rock the bike, see if this fixes it.
if that works, ... then i"ll have to take the backend apart again ;-(

This is not obvious but you can assemble the starter backwards and it will spin backwards as a result. Don't ask me how I know this ..............

Pushed the bike, didn't work
Which way should it rotate?

And how can i test it?
- wire to the body
+ wire to the Brush bolt

Thats the way to test it but be careful as it will try to jump off the bench so clamp it but not a good idea to hold it around the round bit in the vise as you can easily crack the magnets. Hold it by the 2 little tags the bolts go through.

Any idea which direction it should spin
CW or CCW face from the rear (two bolt holes) to the front (spinning part)

Have you tried poking a screwdriver into the hole to see if the sprag works and then that will tell you which way and if the sprag does in fact work. I should have thought of that in the first place.

Just common sence , should/could have figured that out on my own.
Thanks for thinking for my

Due to weather change in The Netherlands (freezing cold, snow and icy roads)
And the fact that i don't have a warm place to work in, i've posponed troubleshooting for at least a week

If I lived in a climate like yours then I would just have to have a heated shed/garage, without my daily fix of messing about with something mechanical I'd co crazy.

Remove the two long screws, turn the rear end of the housing (with brush holder)
180^o relative to the stator (permanent magnets)........remount the screws.

Your starter motor would know turn in the opposite (and correct) direction.

Hello Inge K,
this means that the marking i made on the housing is no good ?
I'll try it as soon as weather permits.

KR,
Amster

All,

Thanks for the advice.
Today i removed the starter engine again
(temp raised to +5C today) ;-)
I've followed Inge's advice and dispite the markings I made, rotated the housing 180^o.
And.......
All works fine again.

Good result Amster, Inke K or "Ingepedia" as some of us know him is rarely wrong. Now get out and ride.

88

Come to think where is Inge, I haven't seen him for a couple of weeks. Maybe there's no more snow and he's off riding.

yep agree rick ...dont remember he had said he would escape somewhere ....with any luck he is on the road and enjoying a long ...relaxing tour ... cheers inge ...whereever you are

Amster wrote:All,

Thanks for the advice.
Today i removed the starter engine again
(temp raised to +5C today) ;-)
I've followed Inge's advice and dispite the markings I made, rotated the housing 180^o.
And.......
All works fine again.

Well . .  this is really really weird. I too had the same problem this thread is started with and found the solution of 180 degree rotation to work for me too, until today that is. With a diagnosis from the service agent that my sprag clutch is failing I stripped back to the removing the bell housing, cleaned and inspected and refitted the clutch, to find all in what I thought was good working order

upon re assembly the starter still free wheeling, upon reversing the polarity of the starter in situ the engine turned over fine,  so, i thought, do the same again on the starter and . .  fail. no matter how many times I rotate the casing the starter still spins clock wise, when it needs to spin anti - clock wise in order to turn the engine

am I missing something >??

I dont know and would appreciate any possible solutions

thanks guys

your all awesome!

Hello Be Made

Your issue sounds really strange,

If i remember correctly, a member of this forum is calling that "electrickery"  
it just plays tricks on you

sorry i can not be more of a help, but others might be.


kr,
Amster

Be Made, Are you spinning the body containing the stator magnets or the end cap containing the brushes?  You wrote "casing" in the description.  The idea is to reposition the brushes relative to the rotor (what Inge advised), not the stator relative to the brushes (what you may be doing).

robmack wrote:Be Made, Are you spinning the body containing the stator magnets or the end cap containing the brushes?  You wrote "casing" in the description.  The idea is to reposition the brushes relative to the rotor (what Inge advised), not the stator relative to the brushes (what you may be doing).

Ok

I have rotated both the end cap containing the brushes 180 degrees relative to the magnets and that made no difference . .  so  . . I am. for the first time in a very long time . . .left bewildered

For the sake of clarity have you used a screwdriver to operate the sprag gear? so we are sure you have contact if the starter decides to go the right way.

well . . . . I am buggered if I know any more. Heres why

4 attempts the other day at getting the starter motor to spin the right way . . to no avail. Then . . all of a sudden . . electrikery alright . . . one attempt repeating exactly what i did the previous 4 and the starter spins in the right direction ! . .  as I say . . bewildered . . but . . happy now :--))

to answer the question above . . which way do you want it spinning... . .looking at the starter motor from its rear with the output shaft facing away from you it needs to spin . .  clockwise . .  from that view

the sprag clutch is working fine now and we have spin at the starter button once again . I am a happy be - made er now

It aint called electrickert for nuthin you know, the god of it chucks lightning bolts around like there's no tomorrow and for some there is no tomorrow so you cant be too careful.

I read this thread with interest as I took a perfectly good starter to bits as part of going through my bike ... and I didn't mark it up beforehand. After reassembly it spins in the wrong direction (anti clockwise looking from the rear) . I then found this thread and Inge K's advice and thought no problem ....except I think I have the same issue as Be Made. I have rotated rear part containing the brushes 180 degrees many more times than 4 and still the darn thing always spins the same wrong way on my bench. It never reverses direction. (if I reverse polarity on the starter on the bench it changes direction). So as the definition of madness is to keep repeating the same thing over and over again and expecting different results I must be mad and I need help. For clarity I have pictures to show what I have done 

Here's "position one" ( marked case )


Here's "position one" cover off
 

Here's "position two (brush holder rotated 180deg) (note case markings moved) 



here's "position two" cover off to show that the brushes are actually moved 180 deg



Appreciate any help or direction as what the heck is going on. Also I believe there was never anything wrong with this starter until I attempted to "service" it. Commutator looks good.

Rotating the end cap is not the way to reverse the starter.  Take both ends off of the starter main body and make the front end of the main body the back end.  In other words swap ends.  That will reverse your starter.

That does makes sense to me but isn't that different to Inge K's post 15 above ?

However at this stage I'll do anything so I did as you suggested see below the serial number tag has moved wrt first pic)  and guess what the starter still turns in the same wrong rotation!

Does THIS exploded view help?

I didn't read post 15 before I posted my response, but after reading it and understanding what he is trying to do it does make sense.  The idea behind the whole thing is to reverse the polarity of the stator is relation to the rotor.  I believe either method should work.  I'm not really sure if swapping ends does indeed change the polarity but that is what I was trying for. 

What was your original reason for working on the starter. 

FYI - the proper way to mark a motor for disassembly is to put one mark on one end across the end cap and main body and two marks at the other end cap and main body.  One line all the way across like you have it does not indicate exactly how to assemble it.

I was replacing the alternator and thought as I was in there I might as well remove and clean up the starter. Unfortunately I dived in without marking anything as it only required removing two screws .    

I actually even studied Fleming's Left Hand rule in college so I understand that in order to reverse the motion of the starter I need to either reverse the magnetic field or the current so both methods should, in theory work. But ... no matter what I do the motor spins only one way - the wrong way. 

Note I only added those marks to help clarify the pictures - I agree that one line could leave the possibility of reversing the body . However it appears that the serial number tag is always at the driveshaft end ( I know - don't assume anything !).

Are you also rotating the negative brush plate 180 degrees at the same time?

Themason wrote:This is not obvious but you can assemble the starter backwards and it will spin backwards as a result.  Don't ask me how I know this ..............

Probably the same way I dont know anything about it either. Explains why it was difficult to line up the screws. Take it apart again, reverse the centre section and reassemble..

When I had mine apart I did mark it with a screw driver as I also wanted to clean the outside.

When I was reassembling it I found it would go back really easy....the wrong way. To get it back the correct way took some wriggling and rotating the plate to get it back together.

ALWAYS mark it with a screwdriver or something that wont disappear when you get tempted to clean the outside of the casing. Why? Because you need to clean the area under the two Allen bolts that clamp it down to the gearbox for a good electrical connection.

As an old electrician I was taught as an apprentice that any motor must be marked at each end either side of the housing to end plate join with matching centre punch marks e.g. 2 matching punch marks at one end and three at the other.

Punch marks so that they can't be washed off etc.

Cheers

I appreciate all the responses but the initial issue I have has still not been resolved. I have rotated the brushes as - I think - can be clearly seen from the pictures above. This has been done way too many times with the same result - the same wrong rotation. I have also flipped the body . At this point I am about to just buy a new/old starter as I don't see what my next logical step is. Before I do that I will venture out to the garage in a few hours and go through every step again - but I am not feeling confident on a different outcome.

kenrams wrote:That does makes sense to me but isn't that different to Inge K's post 15 above ?

However at this stage I'll do anything so I did as you suggested see below the serial number tag has moved wrt first pic)  and guess what the starter still turns in the same wrong rotation!

I have had a look at 3 starters I have here and the label is at the shaft end and opposite the bolt holes on all of them, so from that the stator magnet case is backwards and rotated 90° to where it should be. The stator magnets being end for end wont matter but being rotated 90° will make a difference because the North ans South poles will be reversed and no matter where you position the brushes the alignment is wrong.

kenrams wrote:From post #28
I read this thread with interest as I took a perfectly good starter to bits as part of going through my bike ... and I didn't mark it up beforehand. After reassembly it spins in the wrong direction (anti clockwise looking from the rear) ...

I could be wrong but I thought the correct rotation was anti-clockwise (looking from the rear) not clock-wise. If this is the case then your starter is turning the right way. Have you installed it back in the motor to test. If it still spins but not cranking the motor then its could be yoyur sprag is gummed up
Just a thought

Thank you for giving me something to reassess Kaptain Holister. I have been going by post 26 by Be Made where he states 

"looking at the starter motor from its rear with the output shaft facing away from you it needs to spin . .  clockwise" 

which is the opposite of what you say. So I stuck my finger inside and moved the sprag gear and it free wheels in a clockwise direction - duh! This means that I agree with you and the starter motor needs to rotate anti-clockwise with the output shaft facing away from you. Which is the way the starter motor is currently rotating. So I stuck the starter in and all is good.

Thanks everyone . But I am still a bit puzzled as to why I couldn't reverse the direction.....

You may not have been able to reverse your motor because of the magnet housing being 90 degrees off as stated in post 39.  If you have future trouble with the starter such as not enough power to turn over engine,  I would try rotating the magnet housing only 90 degrees.