Re: 150HP XP2 Motor any good?
Without knowing the year I can't say but is it a 2.5 liter? If so the engine part is nearly bulletproof. The XR2 and XR6 engines were very good with a great service history. My XRi is one of the best engines Merc ever built in many people's opinion. The Merc V6s are great engines.
The XR2 150 is a 2.0l, vertical reed, carb'd V6, originally oil injected, though some people have pulled the oil injection off.
It's a rock solid, spunky engine. In good tune it'll put out near the top of the 150 HP market band, or around 160 hp. Your's may or may not have a 4" prop LU on it. That, if anything, was the weakest part of the engine. Well maintained, they do well, but they have little tolerance for poor mechanics or maintenance, and usually complain by putting the pinion right out the side. Any 2.0, 2.4, or 2.5 Mercury LU will fit as long as the shaft length is the same, so a lot of XR2's and XR4's have 4.5" LU's on them now.
Some think the oil injection is a weak link. It is driven by a plastic gear with very little force on it. They are extremely reliable unless you grossly overheat the engine, melting the gear. Of course the whole burn down is usually blamed on the oiler. The Oil system module has diagnostics built in. If you don't hear the diagnostic beeps when you turn on the ignition, you don't know if the oil system is working or not. That brings up the other reason the oil system gets blamed for engine failure. It's actually a failure of the operator to pay attention to alerts or the lack thereof and take action.
The most frequent cause of engine trouble is fuel. It's a high performance 2 cycle with about 2 million BTU/hour burn going on inside. It takes seconds with cooling failure, or fuel shortage causing a lean burn and overheat to wreck the engine. They are set up well cooled and fat in mixture so in normal operations that would never be any trouble. Let maintenance lag, however, and all bets are off.
If it isn't running right, don't keep running it.
In the XR series, XR2 is 2.0L, XR4 is 2.4L, XR6 and XRi are 2.5 L. They are so close in design that even major parts like crankshaft will somewhat interchange.
IMHO, the 2 cycle V6 mercury engine is one of the best ever made.
hope it helps
John