Which motor should I keep?

[Gary Busey]

This is a bit late notice to get a good number of replies, but....

I'm about to swap an outboard over unless anyone advises not to.

My new 4.5m half cab came with a 1997 Yamaha 75hp 2 stroke. I'm thinking of swapping it for the 2003 Yamaha 50hp 4 stroke.

Took the new boat for a test yesterday. Max speed 53kmh. Planes at around 20kmh. (This is with the 75 2stroke that it came with, which has a hydrofoil).

The old boat (also 4.5m half cab) did 51kmh max, plane at 20kmh. (with the 50hp 4 stroke, no hydrofoil).

Acceleration isn't noticeably different between boats either.

I haven't swapped big motors before, but I've got a huge frame that spans the boat, and a block and tackle. Since they're both Yamaha I thought it would be an easy swap.

Is there anything I'm forgetting to consider? Or would anyone stick to the slightly older 2 stroke for any reason?

Thanks.

Murray.

[rayke1938]

My personal preference would be for the 4 stroke particularly if you do any low speed trolling.

I would not go back to a 2 stroke after owning a 4 stroke motor.

Are the 2 hulls the same weight as it seems to be a bit of overkill having a hydrofoil on the 75hp?

You may have to play around with the prop to get optimum performance from the motor.

Cheers

Ray

[Gary Busey]

My personal preference would be for the 4 stroke particularly if you do any low speed trolling.

I would not go back to a 2 stroke after owning a 4 stroke motor.

Are the 2 hulls the same weight as it seems to be a bit of overkill having a hydrofoil on the 75hp?

You may have to play around with the prop to get optimum performance from the motor.

Cheers

Ray

Thanks for the reply Ray.

That's how I'm feeling too after having a 4 stroke for a while.

I Don't think there's much difference in boat weight. They both feel about the same for my car to pull, but that's all I'm basing it on.

When you say "play around with the prop", to you mean I may need to try different props or do you mean the little angled fin behind the prop?

Cheers.

[rayke1938]

Try different prop sizes. If you are happy with the existing prop IE it gets up on plane ok and has good top speed and motor runs at correct rev range no need to alter.

If the motor overrevs at full throttle or wont rev out then you need to try different sizes. Solas propellers are very helpful.

Cheers

Ray

[haines490slc]

Keep the two stroke

[Gary Busey]

Keep the two stroke

What's the reason you'd keep the 2 stroke on if it doesn't seem to have more power?

Is it that you prefer the simplicity of the 2 strokes and consider them more reliable? Cheaper to service I guess too.

Thanks.

[Gary Busey]

Try different prop sizes. If you are happy with the existing prop IE it gets up on plane ok and has good top speed and motor runs at correct rev range no need to alter.

If the motor overrevs at full throttle or wont rev out then you need to try different sizes. Solas propellers are very helpful.

Cheers

Ray

Do they let you exchange props until you find the right one?

[rayke1938]

Yes

Cheers

Ray

[crazywalrus]

I would definitely keep the 4 stroke on face value. Two stroke will be a lot more expensive to run than the 4 stroke and much nosier.

[Keen-as-fisho]

Another reason would be that 2 stroke outboards are being phased out in QLD dams.

[Gary Busey]

That's 3 to 1 in favour of the smaller 4 stroke. I'm just finishing the swap now. Next test drive on Wed.

Didn't know about the phasing out in dams either.

Thanks guys.

Murray.

[rayke1938]

Another reason would be that 2 stroke outboards are being phased out in QLD dams.

Urban myth.

Cheers

Ray

[haines490slc]

I just like two strokes better, they have more punch and go harder.

[Scope]

Have you factored in that you're dropping a massive 1 third of your power? If you're used to cruising with a 75 it might be a bit of a disappointment losing that grunt...

[haines490slc]

Have you factored in that you're dropping a massive 1 third of your power? If you're used to cruising with a 75 it might be a bit of a disappointment losing that grunt...

not to mention the hole shot you will also lose.

[crazywalrus]

Another reason would be that 2 stroke outboards are being phased out in QLD dams.

Urban myth.

Cheers

Ray

I thought the older 2 stroke models where? ie Lenthals

[rayke1938]

Another reason would be that 2 stroke outboards are being phased out in QLD dams.

Urban myth.

Cheers

Ray

I thought the older 2 stroke models where? ie Lenthals

Lenthalls is only one may change when SEQ water finishes review or recreational use of its dams.

Cheers

Ray

[Gary Busey]

Have you factored in that you're dropping a massive 1 third of your power? If you're used to cruising with a 75 it might be a bit of a disappointment losing that grunt...

I've only taken the new boat with the 75 out once, so I'm not used to it yet. I was surprised that it didn't feel much more powerful than the old boat did with 50 (both boats 4.5m half cabs). Decided I might as well try the 50 on the new one while I've got both.

[Keen-as-fisho]

Another reason would be that 2 stroke outboards are being phased out in QLD dams.

Urban myth.

Cheers

Ray

I thought the older 2 stroke models where? ie Lenthals

Lenthalls is only one may change when SEQ water finishes review or recreational use of its dams.

Cheers

Ray

I'm not sure Ray, just going off several things I've red and herd However it would be good if they don't, I can't afford to get a 4