cowling
 

Can anybody tell me what in the world would make a motor idle higher when you take the cowling off and lower when you put it on???Also the motor boggs out when you push on the throttle to haul butt,just dies out.What could this be!:sly:

Yes it is a sticking Float as was in my case. Remove and clean your Carbs you see the issue vanish ..Also verify the air vent is not clog by a birds nest or something ..

With all of teh problems your having with this engine, sounds like you need to start checking teh parts diagrams and start from scratch and make sure that all the right parts are on it.

Burnt out exhaust baffles will do it.
Exhaust entering the cowl.

had a problem on a merc 150 where a spark plug wire was old and too close to the the metal cowl latch. losing spark and running poorly. found it when I got a tingle from one latch while removing the cowl with the motor running

I hate to mention it but an exhaust leak under the cowling could do that.

Doug