The Engine

It's a Yamaha Personal Watercraft engine that was common to many models when this boat was built back in 1992-93.

The early model 1992-93 Boston Whaler 13'6" Rage models came equipped with a reliable and durable Yamaha drive-train under the center console. Steering, electronics, engine, all the way down through the 6r8 pump system on these Whaler's comes directly from Yamaha's personal watercraft parts bin. With the mass of parts available for mid 90's Super jets, Waverunners, and Wavejammers make these boats a snap to find parts for not to mention upgrades.

The stock 650cc (actually a 636cc) 50HP engine is a good solid running 2-stroke twin. I would estimate this boat to produce approximately 35HP at the pump. Although this will allow 2 medium sized people plus about 120lbs in gear to plane about 25-27mph. I felt lucky to get that after reading about other owners with over-weight water logged hulls.

The stock engine in my boat was in very good mechanical shape even after 20 years and who knows how many hours of use. It had good compression (140lbs in both) after a testing with my cheap compression tester.:( - I'd recommend a good quality compression tester if you own 2-strokes and test it because I've seen them vary quite a bit. All is good except I don't really trust crankshaft, intake seals that are this old because engines with older deteriorated crank seals or brittle intake gaskets can allow outside air to leak into the lower end during operation. This "air leak" can make the fuel mixture lean enough, at high rpm to cause a piston seizure. Air leaks, not engine modifications, are by far the number one cause of piston seizures on the Yamaha twin motors. These Yamaha jet powered Whalers you run pretty much wide open or nothing. So making sure you have proper air and fuel ratio will allow these engines to keep cool and last under tough conditions.

Like everyone I wouldn't mind a bit more power though...This is why after a little research I'm electing to swap in a 701cc (61x) engine that virtually bolts right in.