Nissan 3.5 bogs down at half throttle...

Hello. I'm a new member and the new owner of an old '99 Nissan 3.5 hp 2 stroke outboard (NS3.5A2). I run it on a '73 Starcraft Seafarer 14' aluminum boat. It will start with a pull or two, idle up fine, and run great for a while. I normally stop and fish and the motor starts great. Then while running it seems to bog down and wants to run at about half choke, half power if that.

I also have fuel pooling in the carberator cover, where I believe an air filter should be, how about it?

I don't know if the bogging down is caused by the carburator flooding or not but that is my assumption.
Also, do I really need to clean the carb each and every single time I use this little motor, or is there a better way? I'm just learning so I'd appreciate any recommendations anyone might have. Thanks!

Sounds like you have a carburetor issue. I would suspect your float is not set correctly and it is overfilling the carb pooling the fuel. to adjust the float remove the carb, attach a clean hose to the fuel in port on the carb and blow through it with the carb upright. To test if it is closing do the same with it turned upside down. If you can still blow through it the float is not closing. Half power also may be an indication of it running on one cylinder assuming it is a two cylinder motor. You may do a spark test on each cylinder.

The 3.5A is a gravity-fuel-feed, 1-cylinder, slide-carburetor 2-stroke. If you start and warm-up well, but are having a too-rich problem when warm, you are likely just too rich, probably because of a float/needle issue. All 2-strokes will spit some fuel at the carb, but pooling is a sign that you have too much fuel. You can also adjust the overall mixture by changing position of the retainer clip of the slide rod, although that is seldom needed. You may want to install a carb kit to be sure that you have a supple needle/seat that closes accurately. OTOH, if you must add choke to keep running, you may be having a too-lean condition, caused either by a restriction at the fuel strainer (inside the tank on the fuel cock) or a similar needls/seat problem. Review the Factory service manual for information.

No, these motors do not have air cleaners.

If you religiously turn off the fuel cock and allow the carb to run out at the end of every day, carb cleaning should be infrequent.