Oil mixed with fuel in my 2001 Honda 50HP BF50A

I pulled out the oil bayonette and oil came out mixed with fuel. What could be the possible causes for this and how can I fix them?

First thing you need to consider is whether or not the engine is operating with the cooling system too cold. Incomplete combustion from a cold engine or extended periods of idling (as in lots of trolling) allows raw fuel to enter crankcase. When was the last time the thermostat was serviced/replaced?
This is actually a fairly common complaint with carbureted outboards.

I also see that there is a serviceable "o" ring on the fuel pump plunger ( item # 19 on the page linked below) and that could be a factor but I'm not sure. http://www.boats.net/parts/search/H...0001 TO BAZS-3219999/CYLINDER HEAD/parts.html
While these pumps certainly can leak fuel into the valve cover and dilute the oil, I've never actually seen one do it. But it is something to check if your thermostat is working correctly and you detect gas still diluting the oil after an oil change.

Thank you, jgmo. I will change the thermostat and the "o" ring. I have not serviced either for over 2 years. One last question: what would you consider a "carburetor kit" to service the 3 carburetors?

First, let me say that I am not the expert on the 50 and it's multiple carburetors. My experience is mostly with the single carbed twins of 20hp and 8hp. However, a carb is a carb and yours are fairly similar to the ones I clean/rebuild routinely.

On the parts page below, I would start with a minimum of 3 sets of item #2 "gasket set" and 6 each of item #22 "gasket, carburetor". The hard parts on these carbs are pretty reliable and a good and thorough cleaning of the passages is usually all that is necessary to bring them back to life.

http://www.boats.net/parts/search/H...3210001 TO BAZS-3219999/CARBURETOR/parts.html

That is with the notable exception of item #19 "jet set". Sometimes, I find this little tube, that is ABSOLUTELY critical to the proper operation of the these carbs, to be almost impossible to get clean. I have gotten in the habit of just replacing them too since my time to screw with them is more than they cost.

They just have the tiniest passage inside and they get a "coating" that makes that passageway even smaller. Maybe an ultrasonic cleaner would get them clean but I don't have one and they have another aggravating problem...they crack and split. So, it's your call if you want to mess with them or just replace them. I'm not kidding when I say they are critical.

The other consideration for messing with your carburetors is the synchronization of the three after you're back together. That takes a special tool with vacuum gauges and a procedure I'm not currently familiar with. So you need to be ready for that. If you don't get the carbs synced, she just won't start and run right.

A Helm Inc. service manual would be a good investment if you're doing the work yourself. It's the most expensive one but it is worth it as all the others (Seloc-Clymer-Haynes) are bogus in my opinion.

Good luck and have a Happy Boating New Year!