Honda 40-hp powerhead compatiable with a 50-hp Powerhead?

[mitchbuck]

I have a 2003 50-hp, 4-stroke, carburated Honda Outboard that needs the powerhead replaced. I have been weighing my options including rebuilding existing powerhead, buying a rebuilt one, or canabilizing the powerhead from another Honda 50-hp. My research indicates that a 40-hp Honda powerhead of that vintage will also work as a replacement powerhead for the 50-hp, but I am wondering if that means I will now have a 40-hp engine? It's confusing because the powerhead part numbers appear to be the same between these two engines....

 

[MattFL]

I have the 50hp and my brother in law has the 40hp. I haven't studied them, but at a glance they appear to be the same, so I wouldn't be surprised if they are the same. I'm not positive where the extra 10hp comes from on the 50, but it's common for the difference to be in the carburetors when engines with different ratings share the same blocks.

 

[Sea Rider]

Could be a simple carburator thing, a carb cam restricted thing, a timing advance/carb sync thing, who knows. Put the 40 aside of the 50 and check if timing advance is same, has a different carb cam ?

Happy Boating