Exhaust leak from upper casing on 70hp?

[Mr. Ed]

This is a fairly new to me motor and, other than low rpm roughness (just put a kit in the carbs) runs great. The motor is a '92 70hp.

I have noticed that at the top rear of the upper casing, there are two square holes that sit side by side. On my engine, the area around this blackens very quickly. Is this 'normal' ... I'm not thinking so. I suspect that I have a gasket or seal in or around the muffler, manifold area leaking. Any thoughts? Is there any one seal gasket in this area that is more prevelant to cause this type of issue? Any method to get at these gaskets with out pulling the power head and working your way down??

Thanks,
Ed

[boats.net]

Those are the exhaust relief holes and if black then engine may be running too rich. Check carb adjustments and fuel pumps.

[Ken]

Ed,
It is normal to have a little exhaust come out the relief holes. Also, when the pressure control valve opens up, cooling water will dump out these holes.
The area around the holes will turn dark due to the carbon in the exhaust. You may be running a little too rich on the carbs - adjust the pilot screws (low speed mixture adjustment) per the Yamaha shop manual.
Good luck [img]smile.gif[/img] ,
Ken K

[Mr. Ed]

Thanks for the info. Have not had it in the water since the carb rebuild last week. So, I'll just wait and see what happens after I get it back in water ... I may have just taken care of the problem.

Thanks,
Ed