My oil sight glass keeps popping out when I ride my at. It's a 125. Why is that? Can someone help please?

 

If you absolutely can't fix it, you could try drilling and tapping it for a NPT pipe plug. That will cure the leak, but you won't be able to see oil level. Put grease on the drill bit and tap, then use a shop vac to get any metal shavings out.

 

We had to replace oil sight glasses at the shop. There are plenty out there for Chinese and Japanese atvs and cycles.https://taotaopartsdirect.myshopify....el-sight-glass Just google your machine and it may lead right to one you need. Plus videos on installing new ones on youtube.