2120 (1995) repowering

[GiorgioThai 0]

After several years of happy cruising, it seems that the time has come to replace the old Yamaha F200 2 stroke.

Given the high price of the new Yamaha engines, I focused towards the new Suzuki series, especially towards the 4strokes DF175 and DF200A.
The seller suggested I choose the DF175, more reliable especially given the low quality of fuel sold in the area.
The price difference between the two engines is minimal (around US$ 700).

My uncertainty is on the (small) difference in power. I do not pretend to have a missile, but not even a rowing boat.

Some of you have already installed similar engines on a Robalo 2120 ?

Considering that my fishing trips mainly take place at more than 20 miles from the coast, I also asked if it is not appropriate to change the transom to install 2 outboards (for example 2 x DF90A). Someone has already done this modify ?

Thank You.

Giorgio
Phuket - Thailand

[2-N-TOW 0]

No experience with the Suzuki's, but what is the difference between the 175 and 200 where fuel quality could be an issue? I would think as long as you are running at least a 10 micron fuel/water filter, what makes it past the filter should be fine. If both motors weigh the same, it is always nice to have the extra horsepower available when needed, especially on these heavy hulls.

[djr33324 0]

I installed a Suzuki 200 four stoke 1 year ago . The new online 4 cylinder because of the weight compared to a 6 cylinder . Top speed is around 39 fully loaded on flat waters , cruises good around 4600 rpm at 27 mph . Mpg at crushing is right at 3.0

 

Personally I think 175 is not enough for these boats . My Robalo is a 1997 2120 and they are heavy . Go with the 200 for the small difference in price

 

Best of luck . 75 hours so far with no issues at all .

[Rooboy 0]

Giorgio Thai, which motor did you go with? djr33324, what prop are you running?

[GiorgioThai 0]

Hi Rooboy,
for now i'm still using the old Yammi 200 2strokes.

Last year i had a problem offshore and half boat went underwater.
The 2-stroke started regularly (it was almost submerged) and I could save the boat.
If I had a 4-stroke, with all the electronics they have, I probably would have gone to the bottom

I don't know exactly the size of the propeller, but i'm thinking is the standard 3 blades inox.

Anyway, with 2-3 persons on board, the cruising speed is 24 knots at 3800 RPM.
Top speed 38 Knots at 5000 RPM.
Fuel consumption about 40 liters per hour.

Edited September 25, 2018 by GiorgioThai

[greauxpete 0]

Care to share what happened offshore?

It could be a good learning experience for everyone on the board who goes offshore.

[2-N-TOW 0]

Giorgio -

I missed your post back in September.  I think you can squeeze a little more performance out of that Yamaha.  At WOT, you should be able to see 5800-6000 rpms.  Anything less means the motor is straining a little.  

First thing to check is if it is sitting too low on the transom.  With it trimmed down neutral, the cavitation plate should be 1 to 1 1/2 inches above the bottom of the boat.  Any lower, you are dragging too much lower unit in the water and that is slowing you down.  If it is at the correct height and the compression on all cylinders is still good, time to start playing with props.  Every inch decrease in pitch should cause a 200 rpm increase.  If you have a dealer nearby that will let you test some different props, I would try two different sizes; one 2 inches less pitch and another 4 inches less pitch.  Compare speed vs rpms in 500 rpm increments to see which one gives you the best all-around performance.

I cannot tell from the picture, but if that is an OX66, those motors are darn near bullet proof.  Granted, going to a 4 stroke would be better fuel consumption and not as noisy, but that motor you currently have will run on just about any type of gasoline and are easily repaired if something does break.