Originally Posted by ISTFlyer

If you need to pick-up your bags at IST, yes, you would need an e-visa as a Canadian citizen.
If you manage to transfer your bags to your final destination, you would not need a visa if you don't leave the transfer and departures area of the airport.

However, it would depend on the check-in agent to transfer your bags to your final destination. Be prepared for a "no" at Kathmandu and allow extra time for your connection at IST, don't risk a connection shorter than 3 hours if you have checked baggage.