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Discussion Starter · #1 ·
So I've just got a yamaha yzf r125 and the speedo doesn't work and I can't find were it has one it's a 2014 yzf r125 it's has not got abs or it's not on the front wheel I was told it a gen 2 can anyone help me
 

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2008 YZF-R125 (180cc)
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post a couple of pics, including the front fork/area..should be easy enough to tell which one it is.

I think the gen2 speedo reading comes from the abs sensor so you wouldn't have a searate speed sensor like the gen1. I don't know whether that reading comes form the front or back wheel (or both) tho.
 

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Discussion Starter · #3 ·
Just found out that the sellers did a engine swap for a older engine the wire harness is a 2014 the speedo goes to the crank case and the engine he put in the speedo runs off the wheels but he didn't have the wheels just the engine so I need to get an external speedo drive thanks for the help
 

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ok so as it happens I'm in the process of doing the opposite.. so putting gen2 wheels + forks onto a gen1 bike, and the speedo has been an area of trickyness.

The problem is that there is nowhere to fit the gen1 speed sensor on the gen2 forks sinc eit's part of the axle assembly and the gen2 is totally different, so just finding a speed sensor won't actually solve the problem.

Even if you were to put gen1 forks on which would allow you to fit the speed sensor, that won't work with a gen 2 wiring loom/speedo since they seem to use different types fo hall sensor which are fundamentally incompatible. gen1 uses 3-wire hall sensor for the speedo which switches voltage, gen2 abs hall sensors are 2 wire which switch current. Literally no way to fudge it that I know of.

Idk enough about how the gen2 measures speed to comment beyond that, i've only done stuff with the gen2 wheels and forks and presumed it must measure the speed from the abs sensor since why wouldn't you.. it's right there. I've not had a complete/working gen2 to play with.

If you need a speedo for your mot or whatever then maybe an aftermarket one? but basically the previous owner has got you in a bit of a daft situation and there's prob not much you can do about it without quite a lot of effort or replacing a very anonoying amount of stuff.
 

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Discussion Starter · #5 ·
I know I'm probably going to just get a GPS Speedo for it now when I got the bike he told me it's just a connection problem on the speedo sensor it has not been my week I've gone from the aprilia rs 125 that is so easy to work on and easy to mod it to a yamaha yzf r125 as it is better on petrol I'm just glad that I kept my aprilia
 

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check with your mot man since that's who will really decide what it needs to have. my dirt bike doesn't have a speedo at all and that seemed to be ok with my mot guy. Others insist you have to have a speedo fitted but it doesn't necesaarily have to be working..etc. it seems to vary from test centre to test centre. My mot man wouldn't accept a gps speedo but was ok with no speedo at all. Make sense? nope, me either but here we are xD

Ooh nice on the aprilia..I rather like those!
 
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