New outboard ??

[lkothe]

I have a early 70's 20HP 2-stroke Mercury outboard engine on my 15' flat bottom boat. It's given me some fits (carb)over the past couple of years.
I am looking at buying a new 4-stroke.
My question is.....Will a 4-stroke 15HP give the same performance as my old 2-stroke 20hp....or do I need to replace with a 20hp?
An off hand guess is the new 4-strokes weigh approximately 35-50 lbs more also.

DNO

 

[kd5rjz]

I would imagine you would need a 25 or 30hp to equal an old 20hp 2-stroke.

 

[two-click]

Be sure to check the rating of H.P. on your boat .I went with a 2 stroke because of the weight , I would have had to drop in H.P. on the 4 stroke due to the extra weight .

 

[dennishoddy]

I would imagine you would need a 25 or 30hp to equal an old 20hp 2-stroke.

Exactly. Extra HP to over come the weight difference.
Ikothe, have you tried running sea foam through the fuel system? You can run almost 50% to really clean out those carbs. Sounds like there is a port plugged.

 

[lkothe]

Carb was pulled completely apart the other day, cleaned up and reinstalled. Fired up but kept flooding, believe float/needle wasn't working. Went ahead and disassembled again but haven't put it back on yet.
Next dry day I'll work on it some more.

 

[dennishoddy]

Sounds like you have the same model I have. Mid 70's 20 HP.

 

[kd5rjz]

With my older OMC engines, I try to rebuild the carbs and change out the water pump impellers every year. I've also gotten to where I carry a spare fuel pump with me.

 

[lkothe]

Believe it is a '72 or '73 model 200.
Never had any problems with fuel pump..... yet.
At times it won't accelerate but typically cleans up and runs decent.

 

[dennishoddy]

Running too rich if its loaded up at idle and cleans out at high rpm. Change the needle and seat? Float still floating? I've worked on one with a leak in the float.