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Old 03-28-2004, 11:34 AM   #1
creeper OP
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Joined: Dec 2003
Location: Puget Sound
Oddometer: 10,718
KTM LC4 clutch lock-out switch

The information below pertains to the US ’03 KTM 640 Adventure. It may also be of use to any street legal KTM LC4 model including the enduro, Duke and Motard... and possibly the 950 Adventure.

For almost a year now I’ve been pondering as to why my bike must be in neutral to start. Obviously, I haven’t pondered that much or I would have investigated the issue sooner.
Anyway, after reading the translated (?) starting description and staring at the wiring diagram, I came to the conclusion that there was a problem with either my clutch switch or the diode it is wired to and I should in fact be able to start the bike in any gear with the clutch pulled in.

I removed the fairing, hooked a multimeter to the two-pin plug connection on the clutch switch and saw no change in resistance when I pulled in the lever… Ah Ha! Bad switch!
I removed the offending switch and retested it (yes, I’m like that) and found less than 1 ohm continuity when I pushed the plunger in with my finger… Ah Ha! Good switch!

Apparently, after examining the parts, it appears that the relationship of switch plunger, the “bump” on the clutch lever intended to depress the plunger, and there proximity to each other was insufficient to engage the switch.
I could see no way to make the lever “bump” higher, or to extend the plunger, so I looked at ways to increase the depth in which the switch screwed into the clutch master cylinder casting.
If I had a mill, it would have been a simple thing to “face off” a bit of the boss (oddly enough, about .060”) that extends out away from the master cylinder casting, allowing the switch (and plunger) to go deeper into the casting, and the plunger to be in closer proximity to the clutch lever.
Instead, I used a hand held lathe, designed to turn down the necks of benchrest rifle cartridge cases, to remove approximately .060” from the shoulder of the switch.
This was sufficient for the lever to fully depress the switch plunger, providing continuity for the diode and finally… in gear starts for me. Ta Da!

I may be the only one on the planet that had this problem… but I doubt it.


First view is relationship of parts
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So... how's tricks?

creeper screwed with this post 03-28-2004 at 12:52 PM Reason: revision of applications
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