2004 Yamaha F75TLR Four Stroke VS a 1985 Yamaha 90 hp 2 Stroke

[Timmstng67]

Hello

I am having to replace my 1985 Yamaha 90 2 stroke as it has made its last trip on the river. I am looking at a 2004 Yamaha F75TLR Four Stroke. It will be mounted on my 1985 Skipper Craft 24SC with "Fiberglass Pontoons"
With the old 90hp I was getting about 23 mph at 5000 rpm. The boat weighs about 2000 lbs. I have been told the Yamaha F75TLR Four Stroke will perform better than the old engine, the dealer I am purchasing the engine from is going to help me with propping the boat correctly with a prop exchange until we get it set up right. I am just wondering if anybody has made a switch like this. any input or comments are welcomed. Also if any body has any Knowledge \ History on the Yamaha F75TLR Four Stroke that would be appreciated

Thanks in advance Tim

[robert graham]

that's a pretty big boat..maybe you should go with a bit more HP than the 90HP you're replacing, especially if you carry a lot of people/baggage and if speed is of any importance. did your old 90HP get sick or die or what? reason I ask is that I run a 1999 Yamaha 90C and it runs just like new, never any problems at all...better knock on wood! good luck!

[Timmstng67]

Thanks
The old 90 just locked up at high speed, it did start again and I made it back in. After tearing the engine down it has spun the crank and the cylinder walls are scared as well as the pistons. I guess the precision blend oiling system is at fault. I never got any alarms it just shut off and I knew it was bad!

A new power head is $2000+some other parts it needs. I can pick up the F75 TLR for $3300 just doesn't seem right to put over $2000 into a 24 year old engine.

I am not interested in speed so much as just having a reliable quite engine. I have been told that the four stroke has more lower end power as well as midrange power than the 2 strokes. and is a 15 hp loss going from the 90 to the F75 really going to be noticed I guess I will find out.

Thanks Tim

[Timmstng67]

Update

Well here is the update with the F75 on my boat. I am running a 13.5 x 14 K prop and turning 5400 rpm with current prop I am going to try another prop to try and get the rpm up but for now this is the data I have . With a full load, all safety gear 2 battery's 15 gallons of fuel and 2 adults and 2 kids and all the stuff you have to take with you when the wife and kids go I am getting 20 mph on the GPS. I lost 3 mph switching from the 90 two stroke to the f 75 four stroke. I made a run of about 30 miles and burned 11 Gallons of fuel so in all I am pretty happy with the F75 it will put the boat up on plane with no problem and it sure is a nice addition on the boat now we can talk and listen to the radio while running full speed .

Tim