XB-500 "Shunt mod" gone wrong

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Last seen: 13 years 9 months ago
Joined: Wednesday, July 30, 2008 - 10:05
Points: 16
XB-500 "Shunt mod" gone wrong

Hello everyone,
Some of you may know from another post the following but since I might get more focus having made a dedicated topic on the issue I decided to create one.

I own an XB-500 and I attempted the "shunt mod" about two days ago. After having finished the procedure*, I put everything back in place and took the scoot for a ride on some hilly areas, and it performed like advertised, faster than usual on the uphill with better acceleration. After I was done riding, I let it charge and when I went to ride it after the charge was full, it the motor did not want to work. There was no smell of smoke anywhere, and the lights and sounds were working fine. The battery charge meter was full as well. I switched between my modded controller to the original, and I got the same results. I checked my fuse box and everything there looked okay as well.

At the moment I have been told that it might be some wire that is not connected right. Thanks zerogas, but I need to ask, how I should go about checking this. So far I have tried to check the green connections, and they seem fine, but that's from a noob's point of view.

My guess right now is that there's something wrong with the motor or whatever cable that powers the motor, but I'm afraid to go into that and making a mess.
*The fact that I got the same result from the original controller is what makes me think that it might be something with the motor.

The abnormalities experienced:
- when drilling the hole in the MODDED controller board, there was a small spark
- when connecting a red cable that i'm guessing is a power cable to another red cable, there is a spark.
--this happened with the REGULAR AND MODDED controllers
- when trying to connect the controller with the battery disconnected, there was no spark, BUT after connecting the controller there was a spark when connecting the power cable to the battery pack.

I hope this little information can be useful for someone to see a solution to my situation. It would mean a lot to me. Thanks in advance for any help. I'm looking for any kind of practical way of checking what the problem might be.

zerogas's picture
Last seen: 2 years 10 months ago
Joined: Tuesday, May 6, 2008 - 17:43
Points: 268
Re: XB-500 "Shunt mod" gone wrong

It's not your motor, bro. The fact that it is throwing sparks is enough to point to a short in your wiring. Trace each wire until you find where it is either coming into contact with metal or pulled slightly out of one of the plug in connectors. The little spade terminals in those connectors pull out very easily.

Keep the rubber side down and the shiny side up.

AztecFemBone's picture
Last seen: 12 years 2 weeks ago
Joined: Tuesday, June 3, 2008 - 14:42
Points: 126
Re: XB-500 "Shunt mod" gone wrong

Hey sbm, can you do me a favor and post a picture or two of your rear wheel assembly, specifically the nuts and washers at the freewheel hub/sprocket and brake?

richardb's picture
Last seen: 9 years 10 months ago
Joined: Monday, August 25, 2008 - 11:35
Points: 117
Re: XB-500 "Shunt mod" gone wrong

Each time you disconnect the battery, you must also then turn the ignition switch to on, and let the capacitors in the controller discharge. This will keep you from throwing big sparks. I did the mod on my XB500, and have gone about 25 miles now with no troubles, and done three re-charges. I was very careful with my wiring though... and in the process I had to repair one connector because a wire pulled out.... not crimped well enough, so I removed the pin from the connector, soldered the wire to it, and then pushed the pin back into the connector till it snapped in place. This is a common problem with these bikes.
Good luck.

Waste Not, Want Not

Last seen: 13 years 9 months ago
Joined: Wednesday, July 30, 2008 - 10:05
Points: 16
Re: XB-500 "Shunt mod" gone wrong

I'm guessing I'm having the issue with the connectors. But I just started college again and haven't been able to give myself time for finding and fixing the short. Hopefully I'll get it fixed eventually.

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