G3 1448PF performance with 25 hp Yamaha 2-stroke

[Keystone]

Good Deal! 8)

 

[hwew]

Here it is. The engine has never been put in a lake. It was test ran when purchased and fogged by the dealer. Than the fuel was drained after that. Was always stored indoors. One thing I will do before firing it up is put in a new water pump impeller.

 

[hwew]

Going to raise the motor 3/8" this will keep the cavitation plate 1/4" below the bottom of the boat.

Just found out the motor weighs 105 lbs. I did not think that there was a 25 hp 2-stroke built that was lighter than 111 lbs.

 

[-coaltrain-]

Wow. That is one nice rig... and a helluva deal.

 

[hwew]

Thanks,
I am curious how fast it will go with the Yamaha.

 

[-coaltrain-]

If I had to guess I would say high 20s to low 30s.

 

[hwew]

That would be great!
One thing I will be installing is a hour meter/tach on it after break-in. This way I can see if it is propped right.

 

[DrNip]

I'm going to venture out and say 28 MPH with just you.

 

[hwew]

Here are the recorded speeds at two different trim settings. With my daughter and I.

30-31 MPH trim hole two.
Trim hole two makes the boat more stable.
Hole shot is good at full throttle.
No porpoising.


31-32 MPH trim hole three.
Trim hole three makes the boat less stable.
Porpoising in small chop.
Hole shot is not as good. Prop will cavitate on full throttle on start off. Need to feather the throttle until speed is over 19 MPH.

Will be putting a tachometer on next month.

Love the 2 stroke Yamaha.

Love everything about the rig.

 

[DrNip]

Very nice speeds! Guess I overlooked the 105 lb 2 stroke.

 

[hwew]

I was surprised my self. Broke the motor in for 3 hours before running full throttle for one minute. Oil ratio will be 25 to 1 for 10 hours. My daughter is pretty light. (80 lbs soaking wet)

 

[DrNip]

I am surprised as well. Congrats on that speed. You have gotten some heck of a deals.

 

[hwew]

Will have the tach this week so I will be able to get a good reading what the engine is turning with the 13" pitch prop.

 

[turbotodd]

At 31mph with the factory 9 7/8 x 11 1/4" prop, it should be right around 6500 RPM. That is not possible with the 25 2 stroke, as the CDI will only allow it to spin 6250 max before it cuts spark. Unless it's got a 12" prop on it, which would put it back down around ~6250, which is quite impressive. Most of them wouldn't pull a 12"

Unless you're running downstream. LOL. My 4 stroke runs 32.3 down river, 28.6 up.

You got a great little motor! Enjoy it. Ain't sold in the states anymore, and Yamaha is beginning to stop supporting them. I'm assuming part of that is due to EPA.

 

[hwew]

Thanks for the info turbotodd,
The number you came up with is close. The problem is there are some variations that plays an effect on the speed. The prop slippage is one. If the boat has less drag than there will be less slippage. Transom height is another. I been told that the prop I am running is progressive pitched. I took the boat out again and the GPS read 31 mph. I do not want this thread to turn into a debate about the theoretical speed that this boat is able to do. Every boat is different. Once I get the tach installed the boat will be taken to the lake and ran. I am pleased with the performance that the engine is able to do. I know the engine is over- revving. But I don't know how much. If it is only 6250 over in RPM's I will most likely leave the prop alone since I am not finished setting up the boat. I am not sure if this engine has a rev limiter. If it is pulling higher RPM's the prop will be changed. It would be nice if the engine is already running close to the max range.

This is what I will do:
1. Install tach.
2. Take picture of dia and pitch of prop.
3. Use the GPS to record speed.
4. Take video of actual operation.

Once everything is completed I will post the pictures and clip.
I think this is fair enough.

By the way I appreciate everyone's input. Am anxious to see the numbers myself.

 

[hwew]

The Tach will be delivered today. Hopefully I'll be able to get the results and post them Sunday.

 

[DrNip]

What tach did you get?

 

[hwew]

I purchased a SenDec tach/hour meter. It is manufactured by Global Digital Instruments. The company sells the same setup to Yamaha with Yamaha's name on it. Had one on the 15 hp yamaha two stroke a couple years back.

The tach is installed. Looks like tomorrow is the day.

 

[Stumpalump]

You might as well make it the ultimate boat and add this: https://www.bobsmachine.com/Combo-Tilt-Jack-Clamp-on-or-BIA-50HP-100-106016.htm

Did you say it had built in tabs? Got a pict of them?

 

[hwew]

Thanks but the transom is 16". No need for a jack plate.
Yes it has 2 small trim tabs welded on the very bottom. If I can remember, I will take a picture of them.