Can anyone help?

I switch on the keyswitch and everything powers up.

I press the starter button and sometimes the starter turns the engine and it fires up, great! However sometimes (seems to be more and more often) there is the click of a relay but the starter doesn't turn the engine. I press the button again and again but still the starter doesn't turn the engine. However if I now put the bike in gear and turn the engine by turning the rear wheel, then put it back in neutral and press the starter button it sometimes turns the starter motor and the engine fires up as good as gold. (Although I sometimes have to repeat this process to get it to turn).

Before I start stripping the starter motor, etc does anyone know the symptoms and the problem?

In my mind I am working towards worn brushes in the starter motor, or a bad earth. Can anyone confirm I'm heading in the right direction or steer me in another direction>

thanks
Dave

This is typical of worn brushes. I had the same problem on my K75.
In any case it should not be a bad thing to open your starter and clean it.

Hi Crazy Frog and thanks for the reply.

I seem to have sorted the problem at least in the short term and will tackle the starter when its warmer.

I detached the connections from the starter and wired the starter direct to the battery (and another car battery just to confirm) using a couple of jump leads. This resulted in the starter turning each and every time the circuit was made. This convinced me it wasn't starter.

Swallowing my pride I downgraded my thoughts to a simple poorly made connection. So I cleaned up all the connections, rubbed them down and applied some vaseline and reconnected everything, and it works.

Just been out on a quick spin round town and it seems to have fixed the problem.

In the middle of all of the above I did try to get the starter out, withdrew the two securing bolts but although it wiggled it didn't come out. So I'll leave that bit of work for warmer days.

Thanks for your reply.

David the problem you have is very similar to what I am trying to solve at the moment. Firstly the starter (or at least mine) comes out quite easily and the only real resistance should be the sealing "O" ring so a bit of persistence should do it. I actually had my starter motor "professionally" overhauled which ended up with new bearings and a clean but no new brushes. Combine that with a damaged starter relay and I was (am) going round in circles. Essentially I had everything reconnected with another relay and new, larger earth leads and it worked perfectly, or so I thought. The next day, yesterday, I had similar problems to what I had before and the only questionable item is the brushes in the starter as they seem to be such a crucial part in the whole electrical system. With luck yours was just bad connections with mine who knows?
Regards,
Phil

Hi Dave the symptoms sound very much like either bad brushes or a commutator with bad sections on it. I suspect the brushes as what is happening I believe when you turn the engine is the vibration makes the brushes move a bit and make contact so it runs when powered up. Same can be said for a relay with bad contacts which a bit of vibration jars into better connection. Brush problems can be diagnosed sometimes by rapping the starter motor with a bit of wood end on so a sharp shock is applied to the side of it when you have pushed the start button and the relay has clicked and you are holding the button down will make it run if the brushes are jamming. You can also try giving the electrical box a whack in the same way to jar the relay. All of this assumes all of the electrical connections are good since the relay coil pulling in and closing even perfect contacts cannot supply any current to the motor if there is a bad connection in the thick lead from the battery to the starter relay or from the starter relay to the starter motor. Similarly a bad earth ground from the battery to the engine will also stop the motor turning over.

If you have a high current load like a powerful spotlight try seeing if when the button is pushed the relay clicks and the starter does not turn if there is enough current on the starter terminals to light the light. It needs to be a beefy load since that will tell you power is being delivered to the motor but it is refusing to run. Then you know the problem is internal to the motor, it is a bit of messing about but it does confirm where the problem is.
Regards,
K-BIKE

From what I understand from the Dutch forum for K bikes the starter motor can only be activated if the switches for the following functions are working correctly:
- gear in neutral or clutch disengaged (or is it engaged??)
- besides the 'dead man' switch in middel position and ignition on.

For the correct lubrication of these switches you should have a look at a workshop manual here. I suspect that lubricating with vaseline will over time cause the contacts of the switches to burn in.

Yes you are right Suus62!
These are the 2 early security features on the early Ks. Later, they also put a switch on the side stand.

Hi Guys,
If the kill switch is off on the K100RS16 Valve the ignition and neutral warning light are off as well. When the sidestand is down the engine cranks and all lights look to work normally but it will not start and if running when the stand is flipped down it will stop running.
Regards,
K-BIKE

I think I can add a footnote to my earlier post on this subject. As I mentioned the problem I had was virtually the same as David's and it was a problem that gradually got worse such that most of the time it would not start same as above but when it did the starter relay would "stick" on.

A large kill switch in the earth circuit at least enabled me to kill the bike completely in the event of starter relay problems.

I fitted new brushes in the starter motor as it is not that hard or expensive but it did not fix the problem so I threw all the ideas out the window and started from scratch.

Thanks to Google I found a thread from another guy who kept having starter relay problems even after having it "fixed" by a dealer. His problem was a clutch switch that had high (15 ohm) resistance when closed. A good look at the starter circuit indicates the clutch or neutral switch, and the kill switch and the ignition switch all have to work almost perfectly, as they are wired in series, for the starter switch to engage the starter relay.

In my case, again thanks to another post, it was the starter switch which was occasionally giving high but not extreme resistance when turned to the on position.

The switch is not terribly difficult to remove other than the wiring is under the tank. How I love taking that off! Once removed it is relatively easy to dismantle just watch for very small components. The contacts in my case, and suggested by the post I read, had to be lightly filed. Cleaning on its own had little effect.

While I had everything apart I tested another starter relay and found it only needs about 6V to activate which I was not expecting.

The plus side is everything now seems to be working as advertised (he said touching a small forest) and as an added bonus my brake warning light is almost working perfectly which it never has despite numerous dismantling and cleaning of connections etc.

Regards,

Phil

Having had my starter relay stuck closed due to poor voltage, I decided that the ground wire seemed too small. (Non scientific.)

I fabricated a new ground wire from much heavier guage wire than stock and installed it in the stock location.

In addition to grounding the engine case, I figured it would be good measure to also ground the frame, so I also ran a 2nd earth ground from battery to frame, using a frame bolt somewhere under the seat.

Having a good battery ground seems to have cured some of my electrical problems.

Hi Scottie, One of the problems in our bikes is the number of electrical connections which on 20+ year old bikes will cause problems. I really recommend going over every connection and earth ground with Deoxit and effectively bringing the connections back to as new. Even use it on the battery logs and main earth after doing the full clean the contacts will be the best they can ever be.
Regards,
K-BIKE

Hi folks

Another issue here could very well be the sprag clutch not engaging the starter motor too. Does the starter make any noise as if it is spinning but not engaged at all. I also went through the expense of burning a starter relay unit with poor battery power and melted the power wire to the starter as if there is poor current to the relay it will flutter and subsequently weld the contacts togetehr and then the starter is directly powered to the battery only disconnection from battery post to shop total meltdown. I made a small bracket specifically to attach that lead to the positive terminal on the battery now seperate to the other positive wires so in the event this ever occurs again I can easily crack the nut and remove the wire.
Second thing I did was get a ATM battery with a huge cca that will more than readily hold a good charge.
Third I added an oil detergent to the engine oil to help break down any sludge buildup in the engine and porting to the sprag clutch area and ran it at high revs over about 100ks not speed simply to get the oil extremely hot. No matter what I did during that 100ks it would not engage the sprag clutch at all starter would crank freely. On returning after weekend away I checked the bike and it started first go firing up straight away. I tested it time and again over several hours after the bike cooled off and it engaged and turned the engine over time and again. Now to do oil filter and change. All is working as it should once more