Wondering about this, if 225/250 hp motors are materially more expensive to maintain and repair than 150/175s?  
 

By maintenance I mean periodic annual activities, minor repairs and by repairs I mean more major items such as fuel pumps, sensors, gauges, lower unit repairs, etc.

The maintenance needed annually would be spark plugs, water pump replacement and fuel filters forc 2 cycle engine. 4 cycle gets expensive fast working on power heads. The engine should have a warranty for major repairs.

More hp equals more stress so maintenance costs could be more exspensive.

Tom

I ran a 225 Mercury Optimax for 14 years with 0 repairs.  It had over 800 hours on it when I traded it.  Semi annual lower unit lube, annual water separating fuel filter and plugs every 100 hours was normal maintenance.

Maintenance costs should be identical except for the additional spark plugs on any newer engine.