Nope, the 225 is a very similar motor to what you already have, just a little bore and stroke difference. One thing I forgot is the 225DR has a 24mm carb. so that is one option there, I don't know if the DX has a 22mm or 24mm carb though. I would think it has the 24mm also but the Clymer manual says 22mm (although there are other mistakes in the manual).
1984 Yamaha YT 60 Tri Zinger(current project)
1983 Yamaha YTM 200 (rear suspension kit)..... long term project
2004 BMW R1150R
1972 Honda CT 70
2007 Lifan 110