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LC4 Has decided to stop starting, what could be the prob?

3K views 11 replies 4 participants last post by  tommyduke 
#1 ·
Hi Guys,

My beloved duke has decided to stop working.

On the ride home i stopped at a shop, came back to start it and when i turned the key the neutral light was feint,my lights didn't come on and i got nothing from the igition switch. When i turned the kill switch to the off position the neutral light became brighter.

I managed to kick it into life which also turned all lights on and got me home good as always.

So i went to do some investigation on this on the weekend. I thought it was the battery but on testing it it has 13v so is all good. I did test the voltage at the starter motor and it was only reading 7volts, and on pushing the ignition fluctuated at 7.2 to 7.3 volts. Now to me this is not right, surely it should be getting 12v at the starter. On pressing the ignition i hear a feint clicking at what i believe is the solenoid (next to the battery). Also I can't however get any lights on, just the lit neutral i thought normally when you turn a key you can switch your lights on... which means what, is the key ignition gone?!?!? not sure. I had the front head off to check all connections and they seem all fine.

My initial concerns are the 7 volts getting to the starter. Tomorrow i'm gonna try and bypass the solenoid(if that's what it is) and put 12v to the starter and see if that works but does anyone have any other suggestions?

I thank you in advance for any words of wisdom :)
 
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#2 ·
I reckon your battery maybe gone as I have a battery In my supermoto that charges fully but then the battery dies with in two cranks of the engine and sometimes after a complete charge will not even move the starter it will just click the solenoid
 
#3 ·
Thanks for your quick response

Hmmm, maybe, but uncharged it still reads 13v which i thought was normal and when i plug the optima charger in it still has no effect. I have another bike so i will try and use that battery to see if it makes a difference. I hope so because i'm worried it's in a whole world of poo!!!!
 
#4 ·
I did test the voltage at the starter motor and it was only reading 7volts, and on pushing the ignition fluctuated at 7.2 to 7.3 volts
You should have 0 volts permanently across the starter and only 12 volts when activated by the start button.

If you have 7 volts across the stater then the solenoid must be stuck on (contacts welded) and with a flat battery only leaving 7 volts to try to turn the starter motor against the load of the engine.

This may be why your battery went flat in a short journey as the starter was still powered and draining the battery.

The solenoid click should be quite loud, if it is a quiet click then the contacts aren't moving much (contacts welded).


Disconnect the starter, keep the battery well charged and the only thing to be replaced should be the starter solenoid.
 
#5 ·
You should have 0 volts permanently across the starter and only 12 volts when activated by the start button.

If you have 7 volts across the stater then the solenoid must be stuck on (contacts welded) and with a flat battery only leaving 7 volts to try to turn the starter motor against the load of the engine.
Thanks Pebble,

When i say across the starter, i measured voltage at the cable connection of the starter(from the solenoid) and down to earth, i.e voltage arriving at the starter. I will don my overalls and test again although what you say about the quiet solenoid is spot on, it is quiet, like 'ear to solenoid to hear' quiet and there is 7 volts without the starter depressed.

Can i bypass the solenoid, put 12v bridged from the battery to get the starter motor moving?
 
#6 ·
Hi Tommy,

You will need quite a thick cable unless you take the starter motor out of the engine and test on the bench. The starter motor cables are about 10mm to handle all the current it uses when turning the engine. The battery can supply 100amp+ to crank over the engine.
 
#7 ·
Right so an update,

So i believed it was the solenoid due to assistance from Pebbles and some testing with my multimeter. After trawling ebay i managed to get hold of one which arrived in the post today. I wired it in turned the key and.... nothing! DOH! so the problem is not the solenoid!!!! well trial and error i guess, anyone want a spare solenoid?! So back to the drawing board i shall try and check the complete wiring loom for any breaks. Any suggestions would be welcomed or i may finally have to admit defeat and push it to my local ktm garage!!!!!
 
#8 ·
bad earth or more likely ignition switch i would say.. just had exactly the same problem on my offroad buggy, it was bad earth and the ignition switch full up with mud!! cleaned up all the earth points and fitted a new ignition and its good as new...:)
 
#10 ·
bad earths mean loose or poor connection on earth points. as for testing the ignition, pass..! multimeter is your friend.. not very helpful i know.. earths are easy to check, just find them all, (under seat and tank) clean the wires and the point that they touch the chassis and refit. costs nothing other than time. ignition...if you know how to use a multimeter, great.. if not ask a mate or get half an hours diagnostics at a bikeshop and tell them you want them to check the ignition switch first..if either of those dont cure it.....i aint here!!
 
#12 ·
Right, an update to this problem! Having been looking at the battery and changing the solenoid to no avail i notice the dreaded subframe snap and then ironically it all clicked into place! Having a snapped subframe lead to there being no continuity for the earth and therefore neural meaning that the electrics were basically left buggered!!! A quick test by crossing the negative from the battery to the other side of the subframe and Hey Presto, lights on and engine starting over. I'm off to find a welder and get my katie back on the road!!!!

I'd just like to say thanks to all those forums on here that have led me to the diagnosis. keep them going and i hope this will help someone else in the future!!!!
 
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