So today I got my NOS speedo drive from atc500x. Thanks for that Dom. Anyway I took the thing apart to grease it all up and had my 250es one apart also next to it. Now it's common misconception for people to think that these drive gears are geared differently to make up for the 22inch vs 25inch tyre size, either
in the pinion gear or the ring gear. This is a myth. Both speedo drive units share the exact same ring gear and pinion gear. Therefore making all the parts interchangable. The ES one is stamped HA0 and the 250sx HA6.
It is beyond me why Honda sold them as seperate items. Why not just have one part number for the lot of them. It would be great if someone had the means or want to take apart a 350x or 250r one and compare that to the ES and SX one. I know the outer housings are a different shape but I would bet the internals share the same ring and pinion also, maybe just in a backwards setup.
Anyhow, just thought this might be of interest to someone.
I have used the sx speedo drive gear on my 350x speedo setup and I bet it will read fairly accurate.
Cheers.
Matt