Re: Compatibility of 1980 Johnson 200hp and 1982 150hp Motor?......Should I purchase?
The engines have the same rotating assemblies. The blocks are pretty much the same (flatbacks), except the 200 is ported higher and will make more hp, more rpm's at wot. The 200 uses the high compression 235 heads which came out in the 79 timeframe. Excellent heads! I'd absolutely use them instead of the 150 heads. The carbs are interchangeable, but the ones on the 200 have larger throats ( 1 5/16")and will flow more air/fuel. The 200 has rubber intake filler blocks in the intake manifold, good for 5-8 hp. The engines will swap with each other on their midsections. Ignition systems are nearly identical. The value in the 150 is in the power packs (if they are original, they are unlimited packs), ignition components, the lower unit, crank, rods, starter and the trim system. The rubber fuel components are not ethanol-rated so need to be replaced with newer hoses. The trim systems changed between these two model years. The 200 hp engine has a 3-wire trim system with a remote trim electrical box which mounts under the rear splashwell of the boat. The 150 trim system is a 2-wire system. They are not compatible with each other, but could be completely swapped out.
