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Author Topic:   Honda 50HP 13.53MPG @ 4000rpm is possible?
TASH posted 08-17-2004 08:19 AM ET (US)   Profile for TASH   Send Email to TASH  
Hi everyone.
Has anyone measured fuel consumption on montauk with HONDA 50HP.My '73 TASHMOO {Evinrude 75HP Carb} gets 4-6mpg at 3500-4000rpm.
At the first link you can see that Honda gets 13.53MPG @ 4000rpm

The same Boat with a Yamaha F50 TLRZ gets 7.31MPG @ 40000rpm at the second link.

Carolina Skiff - DLX 1965

Engine: Yamaha F50 TLRZ
Propeller Size: 10¼ " X 14 "
Mounting Height : #3
Weight as Tested: 1645 lbs. RPM MPH GPH MPG DB
1000 2.6 0.4 6.50 64
2000 5.7 0.8 7.60 69
3000 8.8 1.8 4.89 78
4000 19 2.6 7.31 86
5000 27.8 4.5 6.18 88
5400 32.1 4.9 6.55 90
No. of People : 2
Seconds to plane : 3.64
Elevation : Sea Level ft.
Wind Velocity : 10/15 mph
Tested with full tank of fuel, one battery, safety gear and test equipment.
Data may vary due to changes in weather, elevation, load and boat bottom conditions.

Is Honda so fuel efficient or 285 lbs more burn double ??????

Peter posted 08-17-2004 08:31 AM ET (US)     Profile for Peter  Send Email to Peter     
At low flow rates, under approximately 1.5 to 2 GPH, off-the-shelf fuel flow meters are not very accurate. My own experience with a Navman 3100 F with a pair of Evinrude 225 Fichts is that the fuel flow readings and MPG at low engine speeds (under 1500 RPM which corresponds to vert low flow rates) are often inconsistent.

If they used a fuel flow meter to make the determination and it was an off-the-shelf system, I wouldn't put much faith in the numbers at the lower engine speeds.

TASH posted 08-17-2004 09:12 AM ET (US)     Profile for TASH  Send Email to TASH     
Thanks Peter
I am looking for a fuel efficient outboard to replace my old Evinrude 75.Do you have any suggestions.I always use my whaler for fishing so i don't need a high power outboard.
Peter posted 08-17-2004 09:39 AM ET (US)     Profile for Peter  Send Email to Peter     
Tash, unless you need a green engine (low emissions), I would repower with a conventional 2-stroke while you still can. The difference in fuel economy between a conventional 2-stroke and a 4-stroke or a direct injected 2-stroke at the 70 HP range is not that much (maybe a gallon per hour at all speeds). Strictly from a cost recovery point of view, it would take MANY years to recover the extra cost of the green engines in fuel savings. In other words, the extra cost of the green engine buys an awful lot of fuel and oil. However, the green engine will extend your range by say 20 percent with the same fuel capacity.

Some like the quiet and lack of smoke. I would rather give that up for transom weight savings and simplicity.

There are a lot of good choices on the market right now.

Moe posted 08-17-2004 11:12 AM ET (US)     Profile for Moe  Send Email to Moe     
We rented an older Guardian Montauk with a brand new Honda BF50 on it. It was propped to reach 6,000 rpm, although the tach was reading half that since they'd forgotten to switch it from two-stroke to four.

The beauty of this motor is the ultra-light weight. In the range between hull displacement speed and planing, there was little bow rise or plowing with the two of us and a small cooler aboard. It just smoothly increased in speed and just eased into planing, rather than plowing until rolling over on plane. Topped out at what I'd guess was about 30 mph.

It wasn't perfect, though. The carburetors aren't going to be quite as fuel efficient as EFI, although I'd guess it got maybe 7+ mpg while we were out. It also wasn't nearly as smooth at idle as our Merc EFI, and it stumbled sometimes accelerating off idle. Unlike an EFI system, the carbs have to be drained for winterizing. With a carb for each of the cylinders, the passageways in the jets, especially the slow jets, are TINY, and easily obstructed by any gum left by evaporating gasoline. But this was a brand new (3 hours) motor we were using.

The Suzuki DF50 is an EFI 4-stroke. Its published weight is 242 lbs, compared to the 205 of the Honda, and the 264 of the Merc BigFoot 40-60HP models. It is a screamer, though, with an operating rpm range of 5900-6500! Despite that, the gearing is only 2.27:1 compared to the Merc's 2.33:1.

Personally, I'm real happy with the Merc, and think the 60HP would be nice on a classic Montauk. It's the largest displacement of these three motors.

BTW, the Yamaha web site shows the small foot 50-60HP motors are now EFI Merc powerheads. The High Thrust ones still show the 50 HP as a smaller displacement motor, and the 60HP as a carbureted Merc powerhead, but both should change to EFI Merc powerheads pretty soon. That puts the Yamaha/Merc and Merc motors at the largest displacement in this power range. I'd opt for 60HP on either to get full benefit from the additional weight.


BQUICK posted 08-17-2004 11:41 AM ET (US)     Profile for BQUICK  Send Email to BQUICK     
I wouldn't call 205 lbs of the Honda 50 "ultra lightweight".
My 50 Merc is 155 lbs.
Moe posted 08-17-2004 12:13 PM ET (US)     Profile for Moe  Send Email to Moe     
I don't know about yours, but the near-obsolete, carbureted two-smoke Mercury 50 Classic weighs in at 204 lbs according to the Merc web site:


TASH posted 08-17-2004 01:11 PM ET (US)     Profile for TASH  Send Email to TASH     
Thank you doth.Your advices was very heplful.You know Peter for me 20% fuel saving is something good, 50% fuel saving is amazing.I am from Greece and i think that gasoline here is very expensive ~1.85€/litre = 8.63USD/Gallon.How mutch is in USA?
If it is only 20% saving you have right it would take about 5 years for me to recover the extra cost but if it 40-50% i am willing to pay 1000-1500€ more for a low emissions green engine.Moe fuel consumption was ~7+ MPH averange,full throttle or cruising?
Thanks again.

Moe posted 08-17-2004 01:28 PM ET (US)     Profile for Moe  Send Email to Moe     
A mix of about 50% at idle to 2,000 rpm, and 50% at 4,500-6,000 rpm. I'll also note the boat didn't fully plane until over 4,500 rpm or so the way it was propped.


TASH posted 08-17-2004 01:40 PM ET (US)     Profile for TASH  Send Email to TASH     
Thanks Moe.
You believe that this is a faulty measured fuel consumption
of HONDA 13.53MPG 18MPH 4000rpm.
TASH posted 08-17-2004 01:58 PM ET (US)     Profile for TASH  Send Email to TASH
elaelap posted 08-17-2004 02:30 PM ET (US)     Profile for elaelap  Send Email to elaelap     
I was pleasantly shocked at the great 'mileage' I got from my Yamaha 50 hp High Thrust four stroke on my smirkless 16'7" Katama. At a comfortable cruising speed (15-18 mph/3600-4000 turns, if I remember correctly), my old girl burnt a miserly 1.25-1.5 gallons per hour, just about the same mileage I get from my Dodge V8 pickup truck in the city! Loolee 3's new owner, CW member Steve/Bodega 17 can verify these amazing-to-me numbers.


BQUICK posted 08-18-2004 10:09 AM ET (US)     Profile for BQUICK  Send Email to BQUICK     
Moe, I was talking about the TRUE classic 4 cylinder 70s and 80 vintage motors. How they can call that 3 cyl a "classic" beats me.......


Peter posted 08-18-2004 11:11 AM ET (US)     Profile for Peter  Send Email to Peter     
Maybe they really meant to call it a "Legend"...;)
TASH posted 08-19-2004 02:08 PM ET (US)     Profile for TASH  Send Email to TASH     

Thank you all. !!
Moe posted 08-19-2004 05:39 PM ET (US)     Profile for Moe  Send Email to Moe     
The "vintage" 50HP motors were probably closer to 40HP at the prop shaft where todays motors are rated.


Bigshot posted 08-20-2004 10:31 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I have a 70hp EFI Suzuki 4 stroke that gets over 10mpg at cruise which is about 26mph @ 38-3900rpm. She burns about 2.5gph. She will also top out at about 39+mph which is fater than your 75hp. I absolutely love this engine and so does everyone else whop runs this combination. SERIOUSLY loook at the Johnson/Suzuki for your rig. Price is not much more than the 50 Honda.

Είμαι επίσης ελληνικά και η οικογένειά μου είναι από Chios. Πρέπει να είστε ένα τρελοκομείο στην Αθήνα αυτό το μήνα αλλά μεγάλη εργασία στους Ολυμπιακούς Αγώνες μέχρι τώρα. Θα επισκεφτώ μια ημέρα... νοτ σίγουρη όταν εν τούτοις. Απολαύστε! Εγκοπή

elaelap posted 08-20-2004 03:59 PM ET (US)     Profile for elaelap  Send Email to elaelap     
I'd probably agree with everything Bigs wrote in the second paragraph of his post right above this, but frankly it's all Greek to me...

Happy Olympics, B.S. and others. I know that one of the events is pole there another one called pile busting?


TASH posted 09-02-2004 04:27 AM ET (US)     Profile for TASH  Send Email to TASH     

Thanks Bigshot.Sorry about my late reply, i was on vacation the past ten days in Naxos.I think that Suzuki 70hp four stroke is ideal for all 16-17ft whaler.
If you come to Greece you can contact me
Athens was a madhouse the past two years but now all constraction works have finish.Chios it's a beauty, i 've be living there 13 months (military reasons).Have you ever visit Greece??
Bigshot posted 09-02-2004 10:20 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Never been to Greece but the rest of family day I will. They did a great job with the Olympics, glad it was not a disaster/embarrassment.
half shell posted 09-08-2004 07:19 PM ET (US)     Profile for half shell  Send Email to half shell     
Tash look at the Honda 50. It is light and the boat sits correctly. heavy motors make the boat sit to stearn heavy for me.However I would also look at the 60 merc I think it weighs the same as the 50 Honda.
I had the Honda on my 1982 Montauk and loved it.I still can not understand why I sold that boat,and I will get another Montauk soon.
Regards Bob
17 bodega posted 09-13-2004 05:12 PM ET (US)     Profile for 17 bodega  Send Email to 17 bodega     
Tony is right about the Yamaha engine on the smirkless hull. The Yamaha 50 high thrust gets incredible mileage and seems to work perfectly on a smirkless hull. It may be the smirkless hull that makes the difference in mileage since there is less of a vee in the hull and I think that has a large effect.

This motor does everything a person can need for saltwater fishing. A perfect match in my opinion.


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