KTM 640 - engine randomly dies

[Queen of Spades]

Pulled the headlight shell and tank/shrouds off. I cannot find a single wire that has a bare spot on it. Nothing is loose.

What on earth would be causing this problem? Please help?

[Aussie Steve]

Does sound like an electrical connection gone bad. They can be a real pain, for example my intermittant charging issue from a while ago was this:-



Fuse looked fine from the outside and tested okay when tested normally, a voltage drop test when it was playing up found the problem and the fuse cover broke when trying to remove fuse.

Sorry but you're going to have to trace the fault, start by confirming that you loose spark when it wont fire (it does crank doesnt it?). id it does from there check for power to ignition system, stator and pickup coil tests when its not working.

[Queen of Spades]

Originally Posted by Aussie Steve

Does sound like an electrical connection gone bad. They can be a real pain,

Sorry but you're going to have to trace the fault, start by confirming that you loose spark when it wont fire (it does crank doesnt it?). id it does from there check for power to ignition system, stator and pickup coil tests when its not working.

Yes it turns over - just no fire. I don't have the right size socket to get the plug out to test that. Thought it was 5/8.

[dolphins13]

Originally Posted by Queen of Spades

Yes it turns over - just no fire. I don't have the right size socket to get the plug out to test that. Thought it was 5/8.

Of course you turned the gas back on? I've messed with myself a few times by forgetting to turn on gas. Especially after I have been dealing with an annoying problem or havnt ridden in a while. Did a fuse blow? I mean it was just purring away and died for no reason? Sounds like something quit, fuel or spark? Have you studied all the info on page 1 of the main 640 thread? To have it just die sounds like gas quit? Your connection held? Maybe you left the plug cap loose? I can't be the only one that has done all these dumb mistakes? I also have a 99 lc4e so I am feeling for you. My bike has been nothing but a dream. To have it not run would drive me nutz. good luck

[Queen of Spades]

Originally Posted by dolphins13

Of course you turned the gas back on? I've messed with myself a few times by forgetting to turn on gas. Especially after I have been dealing with an annoying problem or havnt ridden in a while. Did a fuse blow? I mean it was just purring away and died for no reason? Sounds like something quit, fuel or spark? Have you studied all the info on page 1 of the main 640 thread? To have it just die sounds like gas quit? Your connection held? Maybe you left the plug cap loose? I can't be the only one that has done all these dumb mistakes? I also have a 99 lc4e so I am feeling for you. My bike has been nothing but a dream. To have it not run would drive me nutz. good luck

Fuel is flowing from the petcock just fine. Bike runs crisp and STRONG when it runs. All 4 fuses are in tact. It seems electrical. Just can't find anything obvious, and I'm not very familiar with a multimeter. Wouldn't know where to begin (other than knowing that I would need to do *something* between component A and component B).

[Aussie Steve]

dont need to pull the plug out, pull the lead off, slide an appropriately sized screwdriver into the lead, holding it by the plastic end (you'll know if you dont) about 4mm off a good earth crank the bike. Does a spark jump across to the earth when its going well?

if yes do the test again when its not running

if no check its a good earth and screwdriver is inserted properly and repeat.

when test is done when not running

if there is spark forget electrical, check your plug and carb.

if no spark its electrical, check as per previous post with service manual.

Edit.

after previous post if its electrical find a sparky or someone who knows a bit about auto elec (very basic knowledge is all)

[Queen of Spades]

Cross referencing some helpful looking pages/threads. I'll check for spark in the minyana.
http://www.dansmc.com/electricaltesting.htm

And these.
http://www.advrider.com/forums/showthread.php?t=829642
http://www.advrider.com/forums/showthread.php?t=646279 "KTM LC4 no spark? HELP!?"

[bmwktmbill]

The plug itself can fail, it happens after they warm up. Aussies test works for the system but not the plug itself, put another one in. And you did tighten the plug cap to the lead?

Have you tightened the main fuse?
Not the circuit fuses, the main fuse. Should be back by the battery?

Do you have any saftey switches still working?

Start thinking about how you will test the ignition switch.

On my '02 640a the engine would kick out for no good reason at speed, scared me, it was the ignition switch.

Check the wires coming out of the ignition coil, sometimes they wear against each other.

You say fuel isn't your problem. Next time it dies close the gas tap and open the drain screw on the bottom of the carb, gas will drain until the bowl is empty...hope you get half a tea cup.

Very sorry for your problem.
bill

[Queen of Spades]

Bill,
The bike does not sputter or lose power when it cuts off. Running clean and strong one second, off the next. Not so much as a cough when turning over. After it died yesterday I tried a little starting fluid - still no much as a cough.

I removed then replaced the main 20a fuse by the battery. It required a little effort to remove and replace - it fits snugly in the clips.

The head/taillight, turn signals, horn, neutral indicator, and starter continue to work in this condition.

I suppose the next step is to check that I have spark & rule out a possible faulty plug.

The engine service manual I have is for a 98 LC4 Enduro, not sure what changed between 98 and 99 -- but it does list some detailed instructions for checking different components of the electrical system. Some of the tests have to be done with bike running so I doubt I will be able to do that (if it starts at all this morning).

Still 39 degrees outside, too cold in the shop just yet. I'll dig in a bit later.

[mountaincadre]

Sorry if it's been said before but you have checked it's not another dodgy side stand issue.

[Queen of Spades]

Originally Posted by mountaincadre

Sorry if it's been said before but you have checked it's not another dodgy side stand issue.

No sidestand (or clutch) switch on the bike. All that was removed before I bought it 4 years ago.

[Deadly99]

Was on a trip, a buddies lc4 did something very similiar. Turned out to be a very small pebble in the float bowl. Periodically it would clog the intake, bike would stall. Then it would run great for x amount of time.

Good luck

[dolphins13]

I also got a 98 manual when I bought my 99?

[Boon Booni]

I'd check voltage to the coil.

If you have an inductive timing light, hook it up to the plug wire and see if it's got a reading. Can also remove the spark plug cap and lay it against the engine. The spark should have no problem jumping from the cap to the motor.

Might want to check the plug. I found this on my Vstrom a few years back.



...dual plugged heads meant the bike ran OK, just sounded funny.

[Queen of Spades]

Can someone confirm socket size needed for the plug?