Ok i'll be the bad man & show how i'd press the gear on if i didn't have a press. End result worked out ok. Had a good fitting bearing supporting other end & on the vice plus another that sat over the small step on the small gear to drive onto. Rough but effective. Good reason not to follow me haha. Shed's a mess & so am i.
Does give you an idea of how tight they are!!.
Pics link here too. photos.app.goo.gl/uoRgEdALfhFN9Sf59

I see looking back at Dale's video on the previous page again that he points out there's a step in his shaft so the gear to gear clearance is pre-set.
So your bike could be the same if a 125 or 175, & i hope it is as would make it a lot easier.
The one i used as a demo is obviously different with no step.
Love Dale's videos.

After posting I did some digging through some of my parts and found a complete shaft that looks good so I will probably just install it. Still going to remove that gear and have a look just to satisfy my curiosity. I have a bearing splitter and some pullers that I think will work.

i normally use map torch to torch one side or propane one side and freeze the opposite side and work it out/in/off. it usually helps alot with temp.
gary

Might be just me but i worry about heating stuff super hot--like, does it affect the hardening --i don't know.