Running engine with hatch closed

[Ken]

Every year I never solve this problem to my satisfaction. I have
9.9 four stroke Yamaha; it seems to get starved for air when running
with the engine hatched closed (it then drops RPM and sounds like it is gonna stall). It becomes more pronounced when the temperature is high or at low RPM. I have two air scopes on the engine hatch that I have adjusted to point toward the bow.

I had a four stroke Honda and I experienced a similiar problem.

Anyone have a similiar problem that they solved?

Ken



Kmerson@avaloninternet.net

[Dave]

I have heard of this problem also. I have a 7.5 hp mercury on my CD, but I have never had any problems. The last owner upped the size of the vents to a four and a half inches outside diameter. The other thing you should do is turn 0ne vent so it is facing the stern, that way the air will flow better. Hope this is helpful.

Dave
R&R 25' CD

Every year I never solve this problem to my satisfaction. I have
9.9 four stroke Yamaha; it seems to get starved for air when running
with the engine hatched closed (it then drops RPM and sounds like it is gonna stall). It becomes more pronounced when the temperature is high or at low RPM. I have two air scopes on the engine hatch that I have adjusted to point toward the bow.

I had a four stroke Honda and I experienced a similiar problem.

Anyone have a similiar problem that they solved?

Ken

[Kurt]

I solved the problem by installing a 1.5" plastic pipe elbow in the top cover of the engine and then attaching a piece of flexible hose to it. The other end of the hose (about 24" long) is run up and wired into place inside one of the air vents in the engine hatch. I also modified the exhaust relief port by attaching a hose to it and running the hose out the bottom aft end of the motor well. I could send photos if you're interested.



kjlgpw@aol.com

[Rich]

Every year I never solve this problem to my satisfaction. I have
9.9 four stroke Yamaha; it seems to get starved for air when running
with the engine hatched closed (it then drops RPM and sounds like it is gonna stall). It becomes more pronounced when the temperature is high or at low RPM. I have two air scopes on the engine hatch that I have adjusted to point toward the bow.

I had a four stroke Honda and I experienced a similiar problem.

Anyone have a similiar problem that they solved?

Ken

Dumb question I suppose, but are you running with the drop boards in or out? I can run my unmodified Yamaha 9.9 with the hatch closed if I leave the boards out.



rpassmore42@hotmail.com