Hello my first post, this is my first "K" a 75RT 1993 i have only had airheads before. The bike had been stood for a few years before i rescued it, all went well no major problems getting it back on the road and it sailed through the MOT

I did about 400 enjoyable miles when the indicators started playing up then the lights and starter motor, i have been going round checking earths and in the process of fitting new brushes to the starter motor, something is really bugging me.

on the starter motor input there is a small black wire going to a relay (Load shed i think) on the other side of the coil for the relay there are 2 green wires where i am getting 12v+ when ignition is on, this does not make sense to me as i would have expected it to be an earth on that side can anyone enlighten me as to whether or not voltage shoud be present on the green wires? the starter relay seems to work ok.

Thanks Lou

Welcome Lucky!

The LSR relay coil is grounded via the starter positive feed, and is the source for your problem. (quite common).

And yes, you should have positive on the green wires, since you got the negative on the other side of the coil.

Have a look in the "how to" section, to dismantle and clean the starter

The LSR gets its earth through the starter to earth so that when 12v is applied to the starter the relay releases because it has 12v on both sides and breaks the circuit to the headlight etc for max starting power.

Right thats starting to make sense as one of the brushes as worn out .....

thanks Lou

Gee that is well worn I reckon thats where the problem is.

Thanks to all for your help, job sorted, after replacing the brush assembley carefully cleaning the commutator and a slight mod to the starter motor earth all is well.

I megga tested the earth/ground route from the starter motor and it was not a good circuit so i modified the circuit by putting a direct earth from the casing bolt the picture shows my first effort which will not fit due to the shape of the engine casting but move it to the other bolt and it will comfortabley fit.

Lou

Lucky Lou wrote:I megga tested the earth/ground route from the starter motor and it was not a good circuit

BMW came to the same conclusion....some years later.
K11`s have a separate ground wire from one of the rear end mounting bolt to the battery.

Gongrats with the result.

I ought to sue them for pinching my idea..........

Lou

great result lou ...

and some good pics too .....im sure many folks have visited the starter motor and every thing looked ok to them .

good thinking result on the additional earth as well .

Welcome to the forum, Lucky. As a matter of personal curiosity, how many miles/kilometers are on this bike? Late last year I brought a 1985 model with low miles. I've been putting off opening up the starter for maintenance. I'm wondering how long it will be before I've shot myself in the foot....

Well done Lucky good job. One thought when you say megger tested I trust you don't mean one of those hand cranked high voltage earth testers because I would advise against high voltage earth testing on bikes as most bike and car electrics die at spike voltages much above 50 Volts. Low voltage testing like with a conventional battery powered meter is not only fine but recommended but the crank handle type are a definite no-no.
Regards,
K-BIKE

brickrider wrote: As a matter of personal curiosity, how many miles/kilometers are on this bike?

I've been putting off opening up the starter for maintenance. I'm wondering how long it will be before I've shot myself in the foot....

Just to add to the research, did change mine first time at 15 years / 190.976 km.

Mixed local commuting / long distance.

Hi.. Brickrider I bought the bike by "accident" i have plenty of time on my hands and enjoy a good project my brother who likes his "Thumpers" got wind of an old Enfield for sale so he went to have a look at it (and bought it) when he was there he spotted the K in the guys garage and asked if it was for sale too, when the guy said yes he knowing i like my BMW,s sent me a picture via his mobile 5 minutes haggling over the phone and it was mine for £600.

The bike has just 40,000 miles just about run in, 2 owners from new the first owner only had it 6 months the second owner had used it for occasional touring with his wife and due to arthritis in his knee had not ridden for over 5 years so it was gathering dust in his garage, i felt really bad when i went to collect it as he gave me a full set of BMW luggage and a box of spares( i priced up the bits he gave me including a new Hagon monoshock they came to £450 at Motobins) these items i didnt know about when i was haggling on the phone or i would have given him more.

As i was loading it onto my van his wife started crying saying she felt like she was loosing a child, so i asked him if he wanted to keep it to which he replied no i cannot ride anymore it has to go but look after it as we have some great memories of trips on that bike.

Despite the long lay up it only needed cosmetic stuff i have lots of pictures but as yet cannot figure out the gallery when i do i will put up the images from start to finish.

K Bike i have a sophisticated digital multi meter/ load/capacitance test unit i use for work i know what you mean about blowing diodes etc with the old hand crank units (wheres my dynamite)

Very Lucky Lou