fuel usage on 225 yami 4 stroke - Striper Talk Striped Bass Fishing, Surfcasting, Boating

fishsmith · 07-17-2003, 08:31 AM

Months ago I asked for input on comparing yamaha 225hp 4stroke and the 250hp hpdi 2stoke for a 23 Parker Sport cabin deep V.
( http://www.striped-bass.com/vbulleti...r&pagenumber=1)
The response here and other sites was very good and appreciated.
My buddy got the boat july 2nd with the 225 4stroke. The boat rides like a dream and is nicely laid out.
I've got some numbers on fuel consumption for anyone interested:

Fully loaded the boat weighs 6,000 lbs (150gal fuel and 20 gal water + gear)

Motor Hours = 68
Gallons of fuel = 359
Average Gallons per hour = 5.28

per yamaha fuel flow management:

WOT - 6100rpm/23 gph/ 38kts gps
20kts = 10 - 11 gph (approx 4500rpm)
25kts = 13 - 15 gph

at idle, you can hardly hear the motor but at higher rpms its about the same as a 2stroke, just a different noise more like an inboard.

Thanks again

<EDIT:I had the gallons of fuel screwed up, 509 have been purchased and 150 are on the boat now, so 359/68=5.28>

BigBo · 07-17-2003, 11:16 PM

Those are some pretty respectable numbers for a boat of that size.

Mr. Sandman · 07-20-2003, 12:56 PM

Have you got the right prop? It looks slightly under pitched to me. 4500 seems too fast for 20 Knots. 6100rpm WOT also sounds high. I don't know the numbers for 4 strokes but most big 2-strokes are in the 4500--5500 WOT. I would *think* that 4 strokes are even lower...I could be wrong for these new 4stroke outboards but it seems odd to me that they would be higher then a 2 stroke. (Generally a 4 strokes peak performance is produced at a lower rpm (producing higher torque) ...when compared to two strokes....ie: motor cycle vs auto)

I would check this out with the dealer.

(A over-reving engine could cause bearings to over heat...burning oil....just a though.)

good luck

ps.

I just read thru my service manual for my 2 stroke and it says that there is software in the computer to prevent rpms > 6100 . It starts cutting out injectors to prevent exteneded running beyond this rpm.

fishsmith · 07-21-2003, 08:48 AM

thanks for the input sandman, I'll pass your info on.

Mr. Sandman · 07-21-2003, 09:25 AM

I would be interested to know what your user manual says is the recommeded RPM range for WOT...

fishsmith · 09-03-2003, 09:25 AM

Sorry about beating this dead horse some more, but what could cause a motor to run at a higher rpm. Yesterday I was on 23 grady with a new 225 yammi 4strk, and it maxed out at 54-5500 rpms.
Earlier in this thread I showed the stats for my buddies motor and it ran at 6100rpms, MrSandman mentioned that seemed real high, and I would think a 23 grady and a 23parker would be pretty close a for comparison.
The dealer has been notified, but said not to worry about it.

Any input would be appreciated

Thanks.

Fishpart · 09-03-2003, 09:34 AM

Might want more prop.......That will load the engine down an dkeep the revs a little lower.

Fly Rod · 09-03-2003, 12:44 PM

fishsmith
Should go to your owners manual That should tell you what your recmmended RPM range should be. It is crucial for todays motors to be running around the manafactures WOT.

On my new motor my wot range is 5600-- 5900rpms These new motors are made to run in the high rpm range My boat does top end 39kts. At 4000rpms my boat crusies at 24 kts. Your rpms will also very with how many people or how much weight is on board.

Go to www.theoutboardwizard.bizhosting.com Look to the left of screen and you will see HOW TO CHOOSE THE CORRECT PROPELLER.

Good luck.

Roger · 09-03-2003, 01:39 PM

Quote:

Originally posted by Mr. Sandman
I would be interested to know what your user manual says is the recommeded RPM range for WOT...

A couple prop selection websites list the 225 Yams at 4500 - 5500 rpms. Means fishsmith's buddy should go up about 4 inches in effective pitch to get down into the safe zone at WOT.

fishsmith · 09-03-2003, 02:24 PM

Thanks for the replies, this guys motor has 140+ hours since July 2, this year.
Here are his issues so far:
Twice he was told his lower gear lube looked burnt (he was told it was fine at the 100hr service)

His low oil alarm went off once and the motor was down 2 quarts. To yamahas credit the motor did go down to <2000rpms when the alarm went off.

Do these issues sound like symptoms of an underpropped motor, or a motor with more serious problems.

WannaBeInAParker · 09-03-2003, 03:51 PM

Thanks all,

I own the Parker that my buddy Fishsmith is inquiring about. I have looked at the Yamaha Web Site and found the following specs for the F225:

http://www.yamaha-motor.com/products...cat=High+Power

Notice the Range is 5000-6000RPM for the F225.

Also, the following URL is a performance overview of the F225 with a 2520 Parker, that is heavier than my 2320.

http://www.yamaha-motor.com/products..._019-PKR-A.pdf

I have occasionally seen the engine run in the 6000 to 6100 RPM range, but for the most part WOT is 5900. The dealer claims that it is normal and if there is an issue where the boat is over revved that some automatic option will kick in and bring the throttle down.

As for the prop being oversized/undersized, this concerns me as I have heard that this delaer has done something similar in the past. How do I tell if I have the proper prop for my engine?

Again, thanks for the responses.

-Jack-

Mr. Sandman · 09-03-2003, 04:24 PM

OK. If your engine turns within the rec Wide Open Throttle that it says in your manual you probably have the right prop pitch.

If your engine EXCEEDS the WOT range you need MORE PITCH.
If your engine is LOWER then the WOT you need LESS PITCH.

There are other lots of propeller options for different kinds of boats. And I hate to say this but it IS a trial and error approach. Some dealers will let you try out props (as long as you don ding it) until you find the optimum for your boat. BUT, the BOAT manufacure should have some data on this. They KNOW what it takes to push that boat. Contact them.

I have a very good book called the "propeller handbook, by Dave Gerr". (got it at amazon) it answers all your questions on props and powering. worth owning it for the serious boater. I look to it first before I dig into my Naval Arch, engineering books and tech papers. This is very easy to understand paperback. http://www.amazon.com/exec/obidos/tg...books&n=507846

Fly Rod · 09-03-2003, 04:43 PM

Go to www.iboats.com Click on FORUMS outboards and you will see one for Yamahas. Give year, HP,etc. and tell them your problem. There are some good qualified mechanics thatmight be able to help or lead you in the right direction.

WHAT HAPPENED TO THE 20--30hr check up That is when you get most of your filings in your gear oil ? ? ? ?