Motor runs great.. with cowling off??? Bogs down while on?

Hey all... finally was able to get to the lake and try out the motor again after the seafoam treatment... Seemed to be doing much better and I deep creep shocked it in the lake under load and it was screaming... very nice. I put the cowl back on the motor and it bogged down on full throttle again, took the cowling off and it was screaming. Obviously it is getting much more air with the cowling off, what is going on?

Can anyone pin point what the problem might be. Ran it with the cowling off the whole time and it was defintely running really good and going as fast as a little 4hp can run. As soon as I put the cowling on it would bog down on full throttle, definitely not getting enough air. Seemed like there is a tiny air vent on the top rear of the cowling, and it was not obstructed. Wonder what it is?

If anyone has any suggestions that would be great

I have seen this before, in the case I had it was a exhaust leak into the cowl. So when you put the cowl on it would hold the exhaust gas in and not open up.
Not sure what brand motor you have, but there is a side plate gasket on a Johnson and a base plate gasket that both seal exhaust my issue was the bottom plate on my Johnson 18. So I would start looking for a exhaust leak under the cowl area. Might try soap around the exhaust gasket areas and look for bubbles.

Good luck,

Flintcreek

Never would have thought of that. Figured it just wasn't getting enough air some how, lol.

flintcreek said:

I have seen this before, in the case I had it was a exhaust leak into the cowl. So when you put the cowl on it would hold the exhaust gas in and not open up.
Not sure what brand motor you have, but there is a side plate gasket on a Johnson and a base plate gasket that both seal exhaust my issue was the bottom plate on my Johnson 18. So I would start looking for a exhaust leak under the cowl area. Might try soap around the exhaust gasket areas and look for bubbles.

Good luck,

Flintcreek

Click to expand...

+1

You can also check your plug wires to make sure there is not one that is grounding out with the cover on.