Engine weight

Testy49 · Nov 19, 2022

I have a 98 Nitro 640 lx with a 75hp Tracker that is not worth fixing. Looking to by a new Mercury 90hp. Seems like the weight difference is 150lbs. That seems like a lot to me but would really like to have a 90hp. Have a new SeaStar hydraulic steering that is for a Mercury so that is why the Mercury engine. The old engine plate says it’s weight is 209 and the new Mercury is 359. Any help would be appreciated.

Chobeemauga · Nov 19, 2022

I have struggled with this decision too. I am assuming the 90 is a four-stroke and the 75 is a two stroke. A four stroke is heavier engine. I am probably going to stay with a two stroke to save the weight. You might consider a newer 90 two stroke.

Fishin1.0 · Nov 19, 2022

The weight difference between the Merc 75-90Hp 2 stroke and the new 4 strokes of the same hp is only 60lbs.

Testy49 · Nov 20, 2022

What weight does it say the 2 stroke is? I come up with 150 difference.

Fishin1.0 · Nov 20, 2022

Here are the sites I used,
http://boatspecs.iboats.com/Nitro_by_Tracker_Marine__640_LX_SC__1998/bp/66b118846 https://www.jdpower.com/boats/1998/mercury/outboard-motors https://www.mercurymarine.com/en/us/engines/outboard/fourstroke/75-150hp/From what I can see the 1998 Merc 75 is 305 lbs and the current 75 is 359 lbs. Your boat is rated for a 90 HP. You can shop around a look for a good used motor. I had a 2000 Merc 90 that was on a Bayliner 1802. I owned for 15 years with no issues.
Are you sure your motor is a 75, not a 50 which weighs in at 204, clean and check the engine plate again. Both engines are 3 cyl.