Moderated Discussion Areas
  ContinuousWave: Whaler Performance
  Suzuki DF70 vs. Yamaha 90 2s

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   Suzuki DF70 vs. Yamaha 90 2s
KDW posted 08-08-2003 10:43 PM ET (US)   Profile for KDW   Send Email to KDW  
Okay, Okay, Sorry, Sorry.

I know this thing has been beaten beyond death. However, I am about to make a very tough decision on whether to purchase a Suzuki DF70 4 stroke or a Yamaha 90 2 stroke for my 1971 Nauset. I'm retiring an old 1971 Johnson 125, god bless her soul. I've tried to look all over this site and started with about 6-8 different possible outboards/manufacturers.

I think I have about narrowed my search to 2 choices.
I'm leaning hard toward the Suzuki DF70 due to the following:
1. Fuel Efficiency
2. Reasonable Power / / 4 Cylinders
3. Reasonable Weight (350Lbs?)
4. Whisper Quiteness
5. No 2 stroke Oil needed (no mess and less $$)
6. Future resale of 4 stroke vs. 2 stroke
7. No environmental issues in future

On the other hand, the old tried and true Yami 90 design success can't be questioned:
1. About 100Lbs lighter than the Suzi 70
2. Simplicity, few parts to break
3. Proven dependability
4. Higher top end and better hole-shot than a Suzi 70
5. More abundant Yamaha dealer/repair shops in my area
6. Better torque at cruising speed - not sure?????

The costs of both motors in the box to my door is right at $5,000 so cost won't tip the scale. My only real concern about the Suzuki is power. I'm no featherweight at 275Lbs and my wife and two kids add another, say 325Lbs. Add 12 gallons of gas, packed cooler, and deep cycle battery and
you've got pretty good ballast in the old girl.

Can anyone out there help me? I think I must need a 3 stroke that has DFI and weighs 300 Lbs. Let's call it a SukiYama 100.

Seriousely, any advice is certainly appreciated.


jstachowiak posted 08-09-2003 07:01 AM ET (US)     Profile for jstachowiak  Send Email to jstachowiak     
I'm running the Newport 1979 17' 70HP Evinrude 4 stroke (same as Suzuki) when with me 170 lbs. and my family an additional 300 for 470 plus 25 gallons of fuel, fishing gear, etc. we do 36MPH top end at 5700rpm. With just me 39mph. Swinging an OMC Stainless 17 pitch prop.

I love the engine for three reasons, 1. no smoke, 2. quiet, 3. starts first time every time, no choke or sputter.

For what its worth, my Newport has a rear casting deck/livewell, in which I place my very large tackle box and cooler and with 14 gallons of water it really lays the rear end low, but she still gets up on plane at 18MPH or about 2800rpm.

I believe, other than hole shot, you will not notice a difference.

The other difference is carbs vs. EFI. Right?

KDW posted 08-09-2003 12:17 PM ET (US)     Profile for KDW  Send Email to KDW     
Thanks so much jstachowiak.

It's very reassuring to know the DF70 can still push a load without losing too much speed.

Yep, you're right about the carbs vs. EFI. I wish Yamaha's 90 4s was EFI.......well maybe not because then it would be an even more difficult decision between the Yamaha 90 4s and Suzuki DF70! I'm sure Yamaha will catch-up soon, but the Suzuki deal looks like the best one right now and they've got the warranty to back up their products.

Thanks again for your repsonse and assistance.

I really can't say enough good things about this web site. I've told every Whaler owner I know about it and it is the most useful and informative site I've ever had the pleasure of visiting.


SuburbanBoy posted 08-09-2003 06:15 PM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
Is the Suzuki warranty a declining coverage type? Where it decreases in items and increases in deductable each year into the warranty?


Disco Stu posted 08-09-2003 08:08 PM ET (US)     Profile for Disco Stu  Send Email to Disco Stu     
Just repowered my 1968 newtauk with a df70. Fantastic engine, and as far as I can tell it is a perfect match for the boat. It certainly has plenty of power. (17" prop, 3 adults, 27 gallons, and lots of gear.)

Don't get too excited about that extended warrenty.

Sal DiMercurio posted 08-09-2003 09:09 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Personally I think your going to be very dissapointed in the 70 hp.
Your going from 125 ponies to 70, darn near 1/2 the horses.
If it were me, i'd certanly fine a boat just like youirs with a 70 on it, then run it & I think you might just lean towards the 90 or even a 115.
Your going to give up a ton of hole shot & top end......better think real hard on it.
David Jenkins posted 08-09-2003 09:36 PM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     
I believe that the two engines in question have the same displacement (same # of cubic centimeters).
jimh posted 08-09-2003 11:49 PM ET (US)     Profile for jimh  Send Email to jimh     
If you need an outboard in the 70-HP range, the Suzuki is hard to ignore. It has a lot going for it mechanically:

--fuel injection
--tuned intake manifold
--reasonable weight and size

It also has a lot going for it in the marketplace:

--competitive pricing
--long warranty

The general belief is that Suzuki is trying to increase its market share by buying its way into the market with a good product at a terrific price. Take advantage of it while you can.

When in coastal North Caroline we saw many Suzuki engines on local boats. There were two large dealers in the area.

captbone posted 08-10-2003 04:48 AM ET (US)     Profile for captbone  Send Email to captbone     
I agree with sal, I would take a look at the 115 Evinrude Ficht. Even with a very tired 125hp, you still are looking at 90-100hp at the wheel and a v4 torque. The 70 suzuki is a great engine but if you are spending that much money, it would be a crime to have you wanting more power.
KDW posted 08-10-2003 11:31 AM ET (US)     Profile for KDW  Send Email to KDW     
Thanks to all for the comments and advice.

I should have clarified in my previous post the my 125HP Johnson has been running on 1 scored cylinder for at least 20 years, but still ran okay except for starting and idle.
The power pack has been the biggest problem, and other than age, its the main reason I'm upgrading (I just don't trust it anymore) Also, this old motor's HP was rated at the head, so I suppose the same motor would be rated closer to 100HP at the prop today. Add the low cylinder and maybe I really only had 80 - 85 HP....just a guess.

Anyhow, top end speed would be nice, but easy starting, dependability, quietness, and fuel economy are very attractive to me and the boat will mainly be used for freshwater fishing and cruising. Also, this boat sits in my yard much more than the lake, so not ahving to worry as much about oil/gas sitting in the carbs is nice too. I've still got the little devil on one should poking me though, telling me to spend more money, forget about the added weight, and buy a hot 2s or larger 4s. I thought long and hard about the Yamaha 90 4s, but wory about buying old technology, carburator synchronization, and worse fuel economy.

As far as the warranty, the dealer told me it covered all but the normal wear and tear items for 6 years. However, with the questions and comments above, if someone has experience with the DF70 Suzuki 6 yr warranty that is different, please advise. Also, I may need to start a different thread, but can someone tell me what is the best hole position set-up and prop for the Suzuki DF90 on a 1971 Nauset? (I'm not planning on a jack plate right now).

Thanks again for the help.


KDW posted 08-10-2003 11:39 AM ET (US)     Profile for KDW  Send Email to KDW     

Just re-read my last questions and realized I said "DF90", when I meant hole position and prop selection for a DF70.

All the possible options are driving me crazy!!!


jimh posted 08-10-2003 12:55 PM ET (US)     Profile for jimh  Send Email to jimh     
Assuming the DF70 is a 20-inch shaft motor, I would start with it mounted one hole up on the Nauset transom.

The bottom mounting bolt situation on these older Boston Whaler boats is often a problem. Sometimes the lower mount was not through-bolted but just screwed into the transom. Look at that situation. I would be interested to learn how your old engine was mounted regarding the lower mounting holes and fastener used.

Do the mounting holes clear the bottom of the transom splash well?

Considering that your Boston Whaler boat is now over 30 years old, I would given some careful thought to how much weight and horsepower you mount on the transom.

The Unibond hull when new has excellent strength and very light weight, but this depends on the integrity of a continuous bond between the hull shell laminates and the dense interior foam. The transom gets much of its strength from wood embedded in the hull, which is subject to rot and decay if not well sealed.

I suggest you stay under the rated horsepower when re-power an older boat.

The Suzuki 70-HP 4-stroke has been reported by several users to be an excellent engine for the 16/17-foot Boston Whaler boat.

Given the fire sale pricing and warranty, it looks like a good choice.

However, as you mention, local dealer support is important. In my area (Great Lakes--SE Michigan) I don't believe there is a Suzuki dealer. I see few of them on the lakes and rivers. This might cause me to not heed my own advice regarding buying the Suzuki outboard.

KDW posted 08-10-2003 02:05 PM ET (US)     Profile for KDW  Send Email to KDW     
Great points jimh!

The transom appears to be in good condition, except on the starboard side near the eye bolt. A small delamination has occurred at the top edge due to what I believe was pulling a heavy load at some time.

All 4 of the bolts that hold my 125HP pass through the transom and are bolted with SS bolts and washers. The motor is all the way down on the transom and the lower slots on the motor backet is not used. The lower bolts come through just above the low point in the splash well and the washer OD is barely above the splashwell bottom. I don't know if the original installer drilled holes in the engine mount bracket to make it fit above the splash well or if Johnson/OMC provided the bolt holes in the bracket? There looks to be plenty of "meat" in the bracket for the current set-up.

I wonder now if the Suzuki will mount using the same bolt pattern, or if I will need a jack plate or lag bolt the lower bolt holes using the lower slots? Does the Suzuki have two independent lower holes located above the lower slots? Does anyone know if the Yamaha 90 2s Have these holes?

I suppose if weight/HP ratio is important, then that puts another feather in the Yamaha 90 2s cap.

Thanks for the help and important insight.


Bigshot posted 08-11-2003 12:06 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I replaced my 90hp Yamaha with the DF70. I would do it again and again and again.....

Yamaha did maybe 41-42 WOT and Zuki does about 39. Holeshot is faster with the 90 but only with light load. Put 4 people in each boat and holeshot is about even. Yamaha was good on gas, especially compared to your current engine but the 70 is unbelievable. I swear gnomes put gas in my tank at night because it sure does not burn any. I avg about 1-1.5gph per tank where my Yamaha did closer to 3. No smoke, quiet, efficient, and resale should be better. Plus the controls etc are cheaper than Yamaha and you can use your old prop if it is a 17".

Get the Suzuki or Johnson equiv. 70hp.

KDW posted 08-11-2003 03:06 PM ET (US)     Profile for KDW  Send Email to KDW     
Hello Bigshot.

Thanks for the information.

I've heard nothing but good stories from a variety of members about the Suzuki DF70. It sure helps to know from someone that has had a Yamaha 90 and how the two compare. Also, given my needs, sounds like the perfect engine for the next 32 years!

My only concern now is how to mount and prop selection. My old '71 Johnson 125 has two holes (I think maybe "blind holes")above the lower slots where the lower bolts are mounted,so the lower bolts do come through at the bottom of the slashwell. I wonder if the Suzuki has these same two holes? If not, I guess I can always install a jack plate.

Also, I've heard both the 18" and 19" props run well. If you don't mind me asking, which would you choose and why?

Thanks so much for your help!

Kenny Wyndham

Bigshot posted 08-11-2003 03:46 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
You should be able to tell if in blind holes by whether or not the nuts stick out the bottom of the engine. If you only see one set of nuts(on top) then you are in the blind holes. Mine was already mounted to the plate so not sure if it has the blind holes. $150 jackplate solves that problem with 10 minutes of drilling through the plate. I recommend the plate anyway, they like to mounted high. I think the 18" should be great but I will let you know, have not run it yet. The 17 would hit redline(5800) at light load. The 19(alum) would maybe do 5400+ and with 3 or 4 people could barely do 5k, not a good prop but I loved it with just me. Hard for me to give exacts because your boat is lighter and hull is somewhat different than mine but if getting a Zuki prop, go with the 18".
Disco Stu posted 08-11-2003 08:38 PM ET (US)     Profile for Disco Stu  Send Email to Disco Stu     
I have a 17" with my df70 on the same hull and it is perfect with a fairly heavy load, but I agree that the 18" would probably be ideal.

In fact, does anyone know where to find an 13 1/4 x 18" aluminum prop that is compatable with this engine? I know suzuki ony makes that size in ss, but I am less interested in that.

KDW posted 08-11-2003 09:36 PM ET (US)     Profile for KDW  Send Email to KDW     
Thanks guys for all the useful information.

Several come close, but based on all I've learned, sounds like the Suzuki DF70 is the overall best choice. Guess I'll have to get over passing on a new Yamaha 90 2s for $4,750.....but the DF70 isn't too much more and probably worth the extra $.

The bolt heads at the bottom are not inset and sit above the motor mount surface, so based on Bigshot's advice, sounds like they are the blind holes.

Can anyone out there tell me if the Suzuki motor mount frame has blind holes above the lower slotted holes or maybe a place on the web where I can find mechanical drawings of the Suzuki DF70 frame?

Thanks in advance for all the help. KDW

jstachowiak posted 08-12-2003 10:09 AM ET (US)     Profile for jstachowiak  Send Email to jstachowiak     
Bolt patterns are all standard now no mater the motor make.

Take a look at:

Some pics of my rig and close up of mount.

May help.

KDW posted 08-12-2003 11:31 AM ET (US)     Profile for KDW  Send Email to KDW     
Thanks again Jstachowiak!

From your photos, I see what appears to be a series of bolt holes in the bottom plate and no slot as in my old Johnson. I can only assume the bolt holes are located within the same dimension as my slot. Also, your motor mount does not appear to have the blind holes located just above and a little outboard of the lower holes as on my old motor.

Do your lower bolts clear the bottom of the splash well, or are they lag bolted into the transom? I am trying to avoid lag bolting. I'm trying to figure out if the new Suzi DF70 will just bolt right in place on my '71 Nauset without use of a jack plate, but its looking more like it won't (unless the lower bolts will clear the inside splash well).

Thanks in advance for your advice and help.


Bigshot posted 08-12-2003 01:56 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Honestly you won't know until you try and mount it. You will like the jack plate if worse case scenerio.
jstachowiak posted 08-13-2003 08:52 AM ET (US)     Profile for jstachowiak  Send Email to jstachowiak     
No lag bolts. It bolts thru to the splashwell.

Did a google search and found:

There has been numerous discussion on this board about mounting newer outboards to older Whalers. You can search for some of these topics here:

jimh posted 08-14-2003 12:21 AM ET (US)     Profile for jimh  Send Email to jimh     
Excellent URI reference on engine mounting!

Thanks for providing that.

I happened across a pix recently showing an engine mounted on a Whaler where the installed used the upper hole of the upper set of four and the lower hole of the upper set of four! Nothing attached to the lower holes at all. Very strange.

lhg posted 08-14-2003 12:56 AM ET (US)     Profile for lhg    
I recognize that document as a Mercury installation manual, evidently for a 4-stroke engine.
DaveH posted 08-14-2003 10:32 AM ET (US)     Profile for DaveH  Send Email to DaveH     

Can you get permission to place the Engine Mounting PDF document in the Reference Section?

jstachowiak posted 08-17-2003 09:43 PM ET (US)     Profile for jstachowiak  Send Email to jstachowiak     
If you remove the last part of that link you get to a page that has all merc motor's mounts.

JohnJ80 posted 08-17-2003 11:23 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
not to be controversial, but I would look heavily at the 115 Evinrude FICHT motor suggested by captbone.

I have the 2003 75Hp version, which I think is the same block as the 90 and the 115. The thing is incredibly stingy with both gas and oil. I have only used 1.3 gallon of oil all season, running around at least 3x per week (we live on a river) - a lot more than ocasional use.

In addition, when I went through my repower, I was very concerned about engine weight in the back end of my Dauntless 15 since Whalers can have a tendency to porpoise.

I researched this pretty heavily, and it looks like the dry weight of my motor is incorrectly listed at 369lbs. The 2002 ( i believe) shop manual shows a weight of 324lbs and its essentially the same motor. A honda 75 is supposed to weigh in at 370 but it is clearly much heavier than my motor. We didn't have a scale at the dealer (he sells both) but cleary the honda was heavier when we hefted them on the hoist. I think you old motor was like one we had on my dads boat (a 73 85HP) which I think weighed in at about 252 lbs, if memory serves.

I would be concerned about going from a 125HP motor to a 70 on your boat. I always think it is a good idea to be up near the top end of the HP range for a boat.

So, my advice would be to look at the lighter DFI motor in a higher horsepower. After having the DFI motor I would never go back to a 2 stroke (smoke, rougher idle etc...) I also would strongly advise going for a EFI motor. You just can't beat them for convenience and nice running.

KDW posted 08-18-2003 07:51 AM ET (US)     Profile for KDW  Send Email to KDW     
Thanks JStachowiak for the mercury documention info. It will come in handy. Also, I appreciate the comments of Johnj80 about the 115 FICHT.

Just this past week, I found a '98 Montauk with a Mercury 100HP two stroke for what seems to be a very low price ($12,900). I figured I would have a little over 1/2 this cost invested to repower and re-trailer my Nauset, so I might as well go ahead and bite the bullet. Also, this '98 looks new and used very little. I haven't tried it yet, but I bet that Mercury 100 is pretty fast.

Anyhow, I plan to run the new boat a few years and then transfer the 100 Mercury to the Nauset, then put a new 4 stroke on the '98. Maybe Yamaha or others will come out with a light-weight, higher HP outboard by then that rivals the Suzi?

The fallacy in this plan is that I can actually afford to keep two Whalers and/or my wife will let me keep both! I'm going to try though.

Man, the new Montauk has less room for stuff than my old Nauset. Looks like location of the fuel tanks had the largest impact.

Thanks again for all the help.

flawton posted 08-18-2003 04:35 PM ET (US)     Profile for flawton  Send Email to flawton     
In march I put a new yamaha 90 2s on my 81 newport. After 50 hours of operation I will say that I am very pleased with the setup. After reasearching I went with this engine for the following reasons:

1-Weight. At 263 lbs. I couldn't find a better power to wieght ratio. The boat has a very nice attitude in the water.

2-Dependability. Everyone I have talked to that has had these motors have loved them and reported very few problems with them.

3- Cost. The 90 2s was alot cheaper than ay the 100 4s yamaha. It would have taken many many hours to make it up in fuel savings.

4- I like a two stroke. call me strange but i like the smell of a two stroke, lets me know I am where i need to be. ON THE WATER.

Im not knocking the suzuki 70 4s, never been in a boat with one. I see alot of suzukis on the the water but not nearly as many as the yamahas.

One concern that I did have with the 4s EFI, though I have no data to back it up with, is repair costs. I just have a funny feeling that in several years when these computerized EFIs start acting up that they will be expensive to fix (just a hunch).

As far as mounting, this is the 3rd engine on this boat. 1st was a 90 merc stack six, second was a mariner stack 6 115. the holes on my rig are in the splashwell and we had no problems mounting it. THe engine lined up on the 3rd set of holes up and the bottom slide on the engine was all the way up so i couldnt have mounted it any lower. doing so put the cav plate 1.5 " above the keel which has proved to be about right.

Per bigshots' recomendation I put a 17' ss prop on it and turn right at 5,300-5,400 rpms at open throttle.

hope this helps

Perry posted 08-18-2003 05:15 PM ET (US)     Profile for Perry  Send Email to Perry     
flawton, how do you like the perfromance of the Yamaha 90 2 stroke? What is the top speed?
flawton posted 08-19-2003 01:34 AM ET (US)     Profile for flawton  Send Email to flawton     
I wish i could give you a WOT speed but I dont have a GPS. When I am by myself (200 lbs) the boat will really move. It has a sweet spot cruise at about 3900 rpms. I wish I could share some hard numbers on performance but without a GPS it is just pulling it out of the air.
Bigshot posted 08-19-2003 10:40 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
My 90 did 41-42 on the GPS wih a SS 13x17 prop. The 70 does about 39.
Jakemachete posted 07-11-2007 04:34 PM ET (US)     Profile for Jakemachete  Send Email to Jakemachete     
one of my friends has a 1995 montauk with a 1995 yammaha 90. this is one of the most diehard engines ever built no questions asked. he probably has close to 3000 hour yes 3000 hours on his engine with no problems whatso ever. absolutly none. not saying anything bad about suzuki but yamaha is not a bad choice,

he also can hit about 37 MPH with 12 gallons of fuel. but keep in consideration that his boat sits about 4 in. lower than my 1983 montauk.

he burns about 20 gallons going to bimini from ft. lauderdale at WOT

Pulls skiers without problems even with 3000 hours.

truely this is an amazing engine

djd35de posted 07-13-2007 06:21 PM ET (US)     Profile for djd35de  Send Email to djd35de     
Well i can speak from my own experience.
I had a Df70 on a 1984 striper. It was whisper quite and never had an issue whats so ever. I think my bait pump was almost as loud as the engine At idle .
Smooooth as silk and i still miss that little boat. i had around 300 hours on her. I once ran this baby about 40 miles off shore looking for Bluefin Tuna, Did'nt catch any , but what i did catch was SUZUKI FEVER. A great engine.
We left around 4:00 am and did'nt return until 8:30 PM and never shut her off. Could'nt run out of gas if i tried. I had two 13.5 gallon tanks .

Is all i can say is amazing little engine.
But if i did it again i opt for the DF 90.
It had ok power but 90 would be better iam sure.

Good luck however you decide.


Tohsgib posted 07-14-2007 01:22 PM ET (US)     Profile for Tohsgib  Send Email to Tohsgib     
I think he already decided being this thread is 4 years old.

Post New Topic  Post Reply
Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.