Evinrude 112 Special

[nwolfe77]

My motor will run at a max 3500 RPM with the cowling on.

My motor will run up to 4500 RPM with cowling off.

My boat will come out of the hole like a 25ft. boat with a 20hp on it with the cowling on. (NOT GOOD in other words)

My boat acts like a jet ski with the cowling off. (AWESOMELY FAST)

Can anyone suggest to me what's up with this?

[tashasdaddy]

base gasket leaking exhaust under the cowl, or grommet of water pump allowing exhaust fumes up.

[Fl_Richard]

And..... If it only spins up to 4500RPM it's overpropped and possibly lugging.

[emdsapmgr]

The older crossflows had air intakes in the front lower cowl-under the bottom carb as well as in the upper cowl where the grab handle is at the back of the cowling. Later crossflow lower cowls, like yours, has had the air intake removed from the lower cowl. As such, the only air for the engine comes through the grab handle area at the top, back of the cowl. Make sure that the area is open and that some mouse did not plug the hole up over the winter. The 115 engines that year had extra air vents in the side of the cowling for improved breathing.