Changing front sprocket on yamaha yzf-r125

This is me trying to do a walkthrough of changing the front/drive sprocket on a Yamaha YZF-R125 without a rear wheel stand/paddock stand.

Please note: this is not an ideal “how to” video‚Ķmore of just a walkthrough to show what you can expect when doing this yourself. It’s almost certainly not the best way to do this job, but it’s one way, and it uses minimal tools.

If there’s something I’m doing wrong I’m sure it’ll get mentioned on the comments. If it’s something majorly wrong or something I’ve missed I’ll update the video.

Assuming no stuck bolts (there will be some the first time) it should take around 30 mins including removing/replacing fairings. Most likely bolts to be stuck are the rear axle adjuster bolts so it might be good to put a little squirt of wd40 on them the night before.

Normally you would be wanting to use a rear-wheel/paddock stand which can make some bits easier, especially if you run into problems with aligning things, as I did here. However, a stand isn’t actually needed so if you don’t have one you can potentially still get this done.

This bike was running a 13 tooth front sprocket which I’m quite happy with and is super fun but it reaches its top speed without an issue, and I want to do some testing of airbox mods (to see whether they work at all) and tinkering with the exhaust/baffles so I sorta need the bike to be struggling to top out, hence going back up to 14t sprocket.

Since changing to the stunt bars it struggles to max out on the 14t – 79mph rather than previous 82mph (more drag), and that time at WOT is where I think the airbox mods might help, if at all so we’re on the 14t for a bit while testing.

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