Parker 2520 performance with Yamaha F250

[Carborita70]

I have just completed break in on a new F250XA Yamaha. However, the performance seems to be off significantly. The previous engine was a 2003 F225 that topped out at 37mph at 5800 rpm. The new engine is hitting 38mph at 6000 rpm, and is slower than previous engine at lower RPM's. Propped with a 15 1/4" X 17" S.S. Honda Prop. Engine is set on lowest mounting hole which should be correct. The link below describes performance of a smaller Parker with same engine; big difference compared to where I am at. Parker has suggested performance may improve with further time on engine. Any thoughts?

http://www.yamahaoutboards.com/site..._pkr_2320slsportcabin_f250xca_3-31-10_oxp.pdf

 

[warthog5]

Engine is set on lowest mounting hole which should be correct.

Meaning it's as LOW as it will go.....or as High as it will go....I just want to be clear in what your saying.

Checking that website..... It says "Mounted in Hole #1". IE: the very top hole on the motor.....which has the motor mounted as LOW as it will go.

This is Totally Wrong! Raise the motor and the boat will come alive.

I had the 2 stroke raised to the 3rd hole.

And was fixing to move it to the 4th / Bottom hole. To raise it all the way up. We quit on it due to selling our other boats and a repower is going to be happening in a week. We will start all over with prop's but I can guarantee the motor will NOT be all the way Down.

You have get the motor UP.....to get the prop right. Raising the motor frees the boat and takes the leverage factor out of the boat some what from just digging a hole on take off and pointing the Bow toward the sky.

 

[Carborita70]

Yes, it is first hole and low as it can be; which is what Parker recommends. I belatedly noticed their is another section on this site related to props and such; good info. I did not see anything regarding height of motor mounts.

 

[BradH]

Are you using the same prop?

Where is it mounted compared to the old one?

Is there a difference in gear ratios?

 

[DaleH]

WHERE is the vent plate at crusing speed?

Fhugghedabout the dealer and read this ... viewtopic.php?f=19&t=11163

 

[warthog5]

Yes, it is first hole and low as it can be; which is what Parker recommends.

Listen to the above if you want the boat getting the max speed and fuel milage.

Please show me where it says or where you got the info above. Cause it's BS!

I've picked up .5MPG by raising the motor easily. In the scheme of things that is a LOT.

 

[Carborita70]

Thanks for the replies. I did not take note of where the previous engine (F225txrb) was hung, nor the prop size: the whole deal was stolen and now I am left to wonder. My fault for not paying closer attention, but I was generally happy with how it ran, but felt it was under powered. The Yamaha site is where I found the mounting hole position, though for the F250 4.2L and a Parker 2320. see below

http://www.yamahaoutboards.com/site..._pkr_2320slsportcabin_f250xca_3-31-10_oxp.pdf

It states, mounting hole position #1. The gear ratio for the 4.2L is 1.75 the 3.3L is 2.00 (30/15) which is the same as the stolen F225 which was ten years old. I suspect the motor needs to come up a notch, and may be pitch up to 19.

Bottom line: if you have neglected to take note of how your motor is mounted and the pitch, cup, diameter as I did...take care of it!

 

[DaleH]

For your prop pitch, you do NOT want to be more than ideally 200 RPMs off the maximum Mfg'r recommended WOT RPMs.

YOU can't decide what prop it will wear, only the motor can. I would test FIRST where mounted and see where the vent plate is, then raise as needed. As Bobby said, get that plate OUT of the water @ cruise speeds ...

 

[warthog5]

It states, mounting hole position #1.

Yea I saw that. My thought's were lazy people. It takes a bunch of time testing and bringing a boat to perform it's best.

It's all on the owner to do this and he's also the one to pay the fuel bill, so there is the incentive.

Lot's of people are not willing to do it and just say screw it. But $600 to do a fill up is not something I can afford all the time.

I have a buddy with a 31ft Yellowfin and twin 300 Suzzies. He's tested 7 pairs of props. He had one pair that gave him the best MPG. But in 2 to3ft seas they would loose and then gain about 200RPM. He opted to loose .1MPG with another pair of props and they only loose 50RPM's in the same conditions.

I'm looking to wring every bit of fuel mileage I can get out of my boat and have it cruise at 25MPH. The ultimate goal would be 3MPG, but I don't think I'll ever see it with any kind of loaded down fishing trip.

 

[BradH]

If you're going to raise the motor and jump to a 19" prop, get with somebody that will let you test a bunch of props. Some dealers do this, I've had great luck with Brett at BBlades and others recommend Ken at Prop Gods.

I totally agree that raising the motor 1 hole will help, but throwing any 19" wheel without knowing what you need or trying a few out could make the problem worse than before.

At 6k are you on the throttle stop and does it feel like the rev limiter is kicking in?

 

[Carborita70]

I used a straight edge to roughly determine where the cavitation plate is in relation to the bottom of the hull, the motor is mounted on a 30.5" Armstrong bracket (did not have mates to help on the water). From what I have read you raise the motor 1" for very foot of bracket, each hole/notch represents 5/8". So, I had the engine raised to the 3rd hole, the photo Warthog posted shows this position. The data is below regarding performance: HUGE difference especially at lower RPM's. However, the 14 1/2 X 19" did not accept hardly any trim, and would blow out a bit on aggressive turns. Should I keep this prop and lower 1 notch or try a 15 X 19?

Prop Size Motor Mounting Position RPM MPH
15 1/4 X 17 First Hole (Lowest) 4600 19
4800 23
5000 28
WOT6000 38

15 1/4 X 17 Third Hole (2nd Highest) 4400 19
4600 25
4800 28
5000 29.5
5200 30
5800 35
WOT 6000 38.6

14 1/2 X 19 3600 19
3800 23
4000 26
4200 28
4400 29
4600 30
WOT 5800 37

 

[warthog5]

From what I have read you raise the motor 1" for very foot of bracket, each hole/notch represents 5/8".

That is a "Off the cuff round figure" to start from. Each hole is 3/4in.

 

[DaleH]

However, the 14 1/2 X 19" did not accept hardly any trim, and would blow out a bit on aggressive turns.

On ANY well-tuned setup you MUST trim in the OB to avoid blow-out on any agressive turn ...

 

[Carborita70]

However, the 14 1/2 X 19" did not accept hardly any trim, and would blow out a bit on aggressive turns.

On ANY well-tuned setup you MUST trim in the OB to avoid blow-out on any agressive turn ...

To be clear no matter how low I trimmed the engine it would blow out a bit on aggressive turns, not a lot but enough to race RPM's 100-200 more. The 15 1/4 X 17 did not do this. I have not tested on open sea yet, but I wonder if this blow out will happen when in sloppy conditions making for slow headway? Normally, I would have another 500lbs of weight when I make a fishing trip. I am curious as to how this will affect performance. Time to make a dive trip and see how it performs and at what economy.

 

[BradH]

Do you have numbers from the 14.5x19 from 4600-5800? That would help a lot.

I would be interested to see how the 15X19 runs at the current (now raised) height. Part of me says it would work, part of me says no...the 46-5800 info will help a lot here.

Think the 14.5 cavitated because the prop lost bite with the water. Did not have enough blade area or cup to hold. Same for when you tried to trim it out. I think it started to cavitate at WOT too cause your slip numbers jumped from 20% with the 15.25x17 to 29% with the 14.5x19.

What are the props you're running? Make, model, # blades, etc?

Do you have a way to check fuel flow (gpm) or mpg? At each speed/rpm would be a huge help.

What are you looking for in the end? Good economy for cruise or WOT performance?

CP people...has anyone tried a 4 blade on a single with a big hull?

 

[DaleH]

CP people...has anyone tried a 4 blade on a single with a big hull?

Yes! I switched to big 4-bladed props by PowerTech years ago even when running a single dirty 2-stroke 225hp on the back of a big, heavy 25' Parker. Now I run a special edition (16" diameter) 4-blade prop made expressly for Suzuki motors, on my rig with a DF250hp on the stern.

The power and torque are incredible! I was able to raise my OBs at least 1-hole when switching to the 4-blades and they stay hooked up better in all sea conditions. I'll still need to trim down some on agressive turns, but that goes for many boats ...

 

[BradH]

I switched to big 4-bladed props by PowerTech years ago even when running a single dirty 2-stroke 225hp on the back of a big, heavy 25' Parker. Now I run a special edition (16" diameter) 4-blade prop made expressly for Suzuki motors, on my rig with a DF250hp on the stern.

The power and torque are incredible! I was able to raise my OBs at least 1-hole when switching to the 4-blades and they stay hooked up better in all sea conditions. I'll still need to trim down some on agressive turns, but that goes for many boats ...

I'm really surprised more people don't run 4 blades. Does Parker set up any boats from the factory with them?

Each engine manufacturer has them as OEM parts, so I don't think that's the problem.

 

[DaleH]

I'm really surprised more people don't run 4 blades. Does Parker set up any boats from the factory with them?

Each engine manufacturer has them as OEM parts, so I don't think that's the problem.

It's not Parker, it's the dealer and engine Mfg'r. And just because they make a 4-blade prop doesn't mean it's ideal for your rig. And personally I don't even trust ANY dealer to set my boat up the way I need it to perform best.

Less Merc props, which are argueably THE best props made for any boats anywhere (... too they don't make big diameter ones for Suzi motors), IMHO one can always improve on a OEM or stock prop by going to a premium brand. And for the record, again less Merc, the OB companies don't make their own labeled props anyway.

 

[warthog5]

Edit;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

I stand corrected.

The older motors and smaller HP ones have the holes 3/4in apart. The new High HP ones have them 5/8in apart and more holes. Saw this today on the new DF-300APX

 

[Carborita70]

Brad H - here are the numbers for both props with Slip calculated. Ken from prop gods was good enough to provide slip calcs for me, which I was ignorant of. He also suggested a 4 blade prop (Powertech OFS4R16 15 1/4 X 16) or adding cup to my existing 15 1/14 X 17 and he was not convinced the 19" prop I became so enamored with was the better choice. By the feel of how it blows out on turns, I can imagine the 19" blowing out frequently running in 3' sea. I can normally run no more than 25-30mph comfortably, I am looking for the best economy in this range, not top end speed. I will look more closely for the maker of the 19" prop, it is quite old a bit rusted and appears to have been worked on a bit. The 17" prop is made by Honda.

15 1/4 X 17
RPM MPH Slip%
4400 19 46
4600 25 32
4800 28 28
5000 29.5 27
5200 30 28
5800 35 25
6000 38.6 20 WOT

14 1/2 X 19
RPM MPH Slip%
3600 19 41
3800 23 33
4000 26 28
4200 28 26
4400 29 27
4600 30 28
5800 37 29 WOT