Stock WR Digital Speedo to Trailtech sensor?

Hello everyone,

I know I am probably asking a stupid question here, so at the very least maybe you can walk away from this with some entertainment value.

Would it be possible to wire an OEM digital speedometer from my 2006 wr450f to a magnetic bolt/hall effect sensor from a trailtech unit?

Here are my motivations for provoking everyone in this manner:

1. My stock pickup cable shroud is cracked in a few places from me crashing it, and it looks like sh**. Works fine...but looks dumb.

2. Pulling/reinstalling the front wheel sucks compared to my buddy's YZ, stock ODO pickup is one more thing you have to align.

3. I would like to have a spare wheel set with different tires, and finding a nice WR front wheel on eBay is like picking fly crap out of black pepper.

4. Finding new fork guards is about the same as finding a WR wheel, and graphics wraps to match? Good luck. :banghead:

5. I hear from other people who get wet and disgusting in tough-guy riding conditions that the Trailtech Vapor is a piece in moist environments. I dont try to intentionally submerge my bike, but it happens.....and my stock speedo has stood the test of time and my idiot behavior thus far. Sounds like they would sell more if they were waterproof.

From what I understand, my stock pickup is a magnet(s) set in a plastic rotor driven by the posts on my hub, whose magnets pass by a sensor coil in the pickup housing (correct me if I am wrong). The Trailtech uses a similar sensor to pick up the magnetic bolt on your brake rotor. How many pulses/revolution does the Trailtech require to operate? Once I am motivated enough, I have already resolved to figure this out on my own with my stock pickup coil and an ohm meter. Even if the pulse/rev is incorrect, the oem unit allows me to correct for overall tire diameter to a certain point, i just forget how far. Maybe I could install extra magnets, or fewer magnets to match; or maybe I could just calculate the difference and lie to my computer to get the output I want. I am pretty good with wiring and electrical, as long as I have a grasp on how something works and what is required for it to do so.

Anyone else masochistic enough to try this yet? :ride:

If you're any good at electronics, you'd have to check (with an oscilloscope) what the signal from the original sensor looks like. It's basically a square wave, where the period (width) of each pulse changes according to the speed. In other words, when you turn the wheel one complete revolution, the amount of ups and downs in the entire wave will change (the frequency), depending how long it takes for an entire revolution, get it?

Then you'll need to compare it to the Trailtech sensor. If they signals are the same, then you're in luck!

Here an example of what you will need to measure:


The trailtech pickup is only one sensor with one magnet mounted, so only one pulse per wheel revolution.

I came to my senses and bought some super kick-butt shrink tube from

It shrinks like 4:1 ratio and ends up really thick. Should be able to cut off my stock cracked speedo wire shrink tube and replace it. I also finally found a deal on an extra front wheel for a WR, so it looks like I found the solution to both issues. Thanks for the input, i'll post some pics of the repair when I get around to doing it... (cold outside)

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