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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: jad01 on March 01, 2026, 02:27:49 PM
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Well, my brick is trying to turn into a brick. :laughing1: Backstory, I recently had the bike on the stand to do the routine fluid changes, rear tire, and repair the headlight switch whose contacts had finally given up and melted into the plastic housing. I wired up relays for the HL using Frankenduck's diagrams. I also took the leaking water/oil pump apart to replace the pump drive shaft and seals.
So.. the bike is back together, but a "new" problem has emerged: it dies somewhat randomly and will not restart for some time. I thought it might be heat related, but there have been two instances where it would not start after having sat for and hour or more. All of the lights work, but the last time this occurred (yesterday), I pulled a spark plug and it is not getting spark while cranking. I will say, when it is running, it runs great.
So... looking at my Clymer and Haynes manuals, I double checked the ignition and kill switches, which are working fine (I had cleaned both previously). I also disconnected the giant ECU plug and reconnected it - it seems to seat fine and when the bike is running, it runs great. The manuals also suggested checking the ignition control module connections and Hall effect sensors, and the plugs, leads, and coils. The plugs are a good color, and the spark is a nice, fat blue one (when they are sparking :laughing4-giggles:).
I am planning to pull the tank and verify that the wiring and connections I moved/disconnected while servicing the bike are clean and tight, but I thought I would ask for any thoughts before I pull the ignition control module and/or Hall sensor. I saw this on the forum regarding testing the module: https://motobrick.com/index.php?topic=6894.0#msg47463. That is probably next in line, but I any thoughts or insight would be appreciated. :think
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First thing I would do is check the ground to make sure its clean and secure.
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The described behavior sounds like it could very well be the hall sensor. The fail when warm is only the beginning, eventually it'll be completely dead. Rather than spending big money the thing can be repaired. There are several descriptions of this repair on this site.
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Thank you both for the information! I did check the main ground and it it is clean and tight. When I pull the tank, I'll recheck the chassis ground on the top loop of the frame.
I have looked for HES repair threads, but haven't seen any. Indigo, if you have a link or two you could share, I'd be interested - thanks!
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Here's one...
https://motobrick.com/index.php?topic=15423.msg137075#msg137075
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jad01, please clarify if you ran the electronic test for Hall sensors at the link your opening post. There is also a static test that can be run using a 12V LED light. It isn't as conclusive as the electronic test but it's a place to start.
Regarding the voltage values in the electronic test of the link: numerical values in the chart followed by this symbol ~ indicate the multimeter should be set to AC voltage for the test, not DC voltage.
Here is a link to a thread that shows replacement options (https://www.k100-forum.com/t14797-replacing-hall-sensors).
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Ah! This is great - thanks Laitch! I have not yet run the test from the link... maybe this weekend. I'll appreciate the link to the rebuild thread. 112350