Thread: Yamaha four stroke

I just purchased a boat with a 2000 model Yamaha four stroke engine 50 hp, does any one know what the maximum rpm is and what would be the the most efficient rpm? Thanks

It should be propped to turn about 5500RPM, I believe.

Thanks Rock I have heard that from one other person also, fully loaded it is turning 5200 is that within standards or should I look at changing props to get 5500?

Originally Posted by CUZZIN

Thanks Rock I have heard that from one other person also, fully loaded it is turning 5200 is that within standards or should I look at changing props to get 5500?

You may be a little over propped, but motor height and weight distribution can also effect this. If you're happy with the performance, I wouldn't do anything much.

Thanks just want to make sure everything is in order with my (new to me) pride and joy.

I have an 05 60 Yamaha 4 stroke. If memory serves, the manual calls for 5000 to 5500. I have mine propped to turn 5400.

You can get the owners manual online from yamaha.com in pdf for free. It'd be a good idea to check what it says for your motor.

I think you're OK at 5,000, but I'd rather see at least 5300 or 5400 assuming the 5 to 5.5 range is correct according to the manual on your motor. You should have a nice hole shot if you're turning 5 even though.

Wannabe...

My bad, I thought you'd typed you were turning 5 even. I see now you said 5200. If the manual says 5500 max for your motor, I'd play around with weight and height to see if you can get the other 2 to 300 before I went through the expense of another prop. You could probably get those rpms pretty easily for free with a little experimenting.

Also, since this boat is new....it's easy to lose those rpms due to weight added as you add stuff to your new boat. You might have to allow for that.

Wannabe...

Ok guys two more questions, I finally got around to trying boat out (the previous owner stated 5200 rpm's wot) it will only turn 5000 with one person and 3/4 tank of gas. It has a 12x14 prop on now i also have a 12x12 prop will the 12 gain me rpm's or loose them? Also it is idling at 12 to 1400 rpm's is this a little much? Seems like it hits a little hard going into gear. Where is the idle adjustment on a 2000 model Yamaha four stroke? Thanks

That is too high. You should me running 700-800 RPM or 900-1000 RPM depending on your model.

You can look at the owner's manual online at Yamahaoutboards.com and it shows how to set the idle. Note that idle is set with the engine warmed up and usually a service tach is used to set idle as some consumer gauges can be inaccurate at the lower 10-15% of range. But, use what you have.

As far as the 12 goes, it will increase your RPM as it is a lighter load to push.

The 12 is the diameter of the prop and the second 12 (or 14) is the pitch. That is the distance forward it will travel through the water in inches in one turn (in theory that is, in reality, it will only travel like 80-90% of that distance due to all kinds of high tech reasons).

So, putting a 12 pitch vs a 14 pitch will make for a lighter load on the motor, but will slow your top speed down. There are several factors that will affect how fast your boat goes, not the least of which is how the motor is mounted and how the boat is loaded. You should look for 5500 RPM with a moderate load, unless you run a full load all the time. You're trying for best overall performance, not just under once circumstance.

Originally Posted by Fishtaco

That is too high. You should me running 700-800 RPM or 900-1000 RPM depending on your model.

You can look at the owner's manual online at Yamahaoutboards.com and it shows how to set the idle. Note that idle is set with the engine warmed up and usually a service tach is used to set idle as some consumer gauges can be inaccurate at the lower 10-15% of range. But, use what you have.

As far as the 12 goes, it will increase your RPM as it is a lighter load to push.

The 12 is the diameter of the prop and the second 12 (or 14) is the pitch. That is the distance forward it will travel through the water in inches in one turn (in theory that is, in reality, it will only travel like 80-90% of that distance due to all kinds of high tech reasons).

So, putting a 12 pitch vs a 14 pitch will make for a lighter load on the motor, but will slow your top speed down. There are several factors that will affect how fast your boat goes, not the least of which is how the motor is mounted and how the boat is loaded. You should look for 5500 RPM with a moderate load, unless you run a full load all the time. You're trying for best overall performance, not just under once circumstance.

Thanks Fish, I will check the idle, as far I know this motor was set up the way it is new, but now i'm really confused how or what can I do to get my rpm's up at wot, I dont want to loose any top end but the way it is set up know its got real good hole shot, do I need to put the 12 on? Thanks again