Yamaha, 4 stroke motors

[Jazzmanic]

Yep, I'm definitely in C-Weed's and Sea Wolf's camp. We got a CD-22 this year and love it. However, we were both brand new to boating and depended on the advice of our salesman regarding powering the engine. He told us that 70 hp was sufficient, that all the CD's used to be rigged with 70's. So they convinced us that a Suzuki 70hp was the way to go due to the fact that it was fuel injected. It wasn't until after our boat was rigged that we started reconsidering the 90 hp as opposed to the 70 hp that was installed. Looking back, we should have switched out to the 90 right then and there while it was still at the factory. All season, it's felt like the boat has been underpowered. We know our prop is not right because we haven't ever been able to reach the RPM range at WOT. So at this point, I will change the prop to a 13" pitch to tell whether or not it's the engine or the prop. So far, we like the Suzuki, we haven't had any problems with it. It's quiet, starts right up and trolls smoothly at a very low speed but I guess we'll have to see if we're having a problem with it after switching out the prop. In either case, it's been extremely frustrating not being able to have that extra power when we need it. We usually run with full gas tanks, full water tank, lots of gear and need the extra power a 90 hp would provide.

So, if we were to do it all over again, we would have definitely ordered the 90 hp over the 70 for the $900 or so difference in price. Now, if we wanted power up, with approximately 80 hours on the engine, it will cost at least $2500 (new motor less trade-in + labor). I'm pretty sure we'll be moving up before next season but we'll hold off for now seeing as how Joe mentioned that Honda might be coming out with EFI.

Good luck in your decision-making. Hope this helps.

Peter
C-Dancer

[Sneaks]

I still have difficulty seeing how 90 hp will have any perceptable difference over a 75 in actual use if both are properly mounted/propped. Certainly not enough to call 75 hp "underpowered."

My Yamaha EFI 75F will put the C-22 over 30 mph consistently in flat water and it always planes in less than 7 seconds. Because our boating is almost always So Cal salt water, rarely do conditions allow a comfortable ride in excess of 15-17 mph, and our usual very comfortable cruise setting is about 13 mph. At no time do we feel underpowered, nor do we have trim tabs. It does list to starboard when I'm single handling it, but that's a function of my fat arse, not the boat itself. It's also true (at least for the Yamaha) that the 90 loses some of the 75's low end torque in favor of high RPM horsepower.

I would expect almost exactly the same performance out of the equivalent Honda, Suzuki, or Mercury.

So given those conditions, how would the added 15 HP benefit me, Chris and Joe? Peter, I think you really need to look into both the prop and possibly the engine mounting height itself.

Oh, and as an aside to the Dodge proponents, my 11 mpg figure was based on towing our 8,000 lb. 5th wheel, not the Jenny B. I have no mileage figures for that rig since so far the longest tow was about 120 miles, but all bragging and teasing aside, there ain't much difference between the stock common rail diesel offerings anymore.

[Redƒox]

Hey ya gize... I went F-115 mostly cuz it's built like a brick you-know-what internally made more stout (that's why it's so much heavier than the F-100 or 90 ) no, don't really need the extra horses of the 115 (though windin-her-out on flat water is exhilarating) it's the heavy-duty part I like most, should last longer!
The F-115 is in a class of it's own, and only Yamaha would go to lengths to make it so. Me thinks anyway
Get anal.... looks at the 'specs when makin a choice...
I better get outahere now....

[Jazzmanic]

Sneaks,

Believe me, I would not wish anything more than to know that I'm getting optimum performance out of my Suzuki DF-70. Being inexperienced and all, I'm hoping that the prop situation takes care of my power problems. All I know is that the RPM range is 5200-5800. Our RPM at WOT is 4400 at best. We've only been averaging 12-14 knots and reaching only 18-20 knots at WOT in flat water. I have been reading posts regarding the proper prop size and pitch and hopefully the 13" pitch does the trick. If that takes care of the problem and we start getting the same perfomance as you do, I'll be happy as a clam and hopefully won't feel the need to add an additional 20 horses.

Thanks for the tip on the engine mounting height. That will be the next thing to look at.

Peter
C-Dancer

[Sea Wolf]

Peter / C-Dancer-

That Suzi DF70 is built on the same block as their DF60. They both have 79.2 cu. in, or 1298 cc. Two valves per cylinder, SOHC. Nice and light at 335 lbs.

The Yamaha 75 and 90 are built on a block with 97 cu. in or 1596 cc. Four valves per cylinder, DOHC. 369 lbs.

The Honda 75 and 90 are built on a block with 97 cu in., or 1590 cc. Three valves per cylinder, SOHC. 384 lbs.

The Honda and Yamaha 75 and 90 are 23% larger in displacement than the Suzi 70.

The Suzi 90 and 115 are built on a block with 118.9 cu. in, or 1950 cc. 416 lbs (!) The Yamaha 115 has 1741 cc, the Honda 115 2254 cc.

The Suzi 90 has 150% of your displacement, the Yamaha 115 134%, and the Honda 115 174%. Think they all have a lot more torque than a Suzi 70? If displacement relates to low end torque and final horsepower, you may find much of your answer right here. Bigger motors are bigger motors.

Averaging the three 90's together, we get Honda 1590 cc, Yamaha 1596, and Suzi 2254, for a total of 5440 ccs, and an average of 1813 cc, some 40% more displacement for the average 90 than the Suzi 70.

So it would appear that there's quite a bit of difference between your Suzi 70 and the 75 and 90 Hondas and Yamahas and certainly the Suzi 90, which is probably quite a brute since it can put out 115 horses in "tuned up" form.

The organization that regulates motor manufacture, the National Marine Manufactures Association (if I remember correctly) also allows a + or - 10% variation between the advertised horsepower and the actual dyno numbers.

I bought the 90 just to be sure I wouldn't be short, period. Hasn't disappointed. The extra 15 horses just make up for the rough bottom paint, but oh well, I'm still doing 30 flat out and loaded up! Joe.

[Jazzmanic]

Thanks Joe for the clear analysis and great info. It's all beginning to make sense to me now!

Peter

[Sea Wolf]

Peter-

Another way of simply stating it is that the Suzi 70 is just a small motor. If they could have stretched 75 hp (or there abouts) out of it, they would have to compete with the rest of the 75's. Joe.

[westward]

Greetings. I've been agonizing over my own 22' cruiser's repower for a few years now. Here's my two cents: 1. I want 90 rather than 70, not for speed but rather for power when heavily loaded. But forget about speed advantages because you won't normally run either motor at top speed. 2. Lighter in the stern is better. There is no serious debate on this issue. 3. Honda makes the best, most reliable motors,(and cars, and lawnmowers, and ATV's....) but doesn't offer fuel injection in our HP range. Too their 90 is moderately heavy. 4. In your weight calculations, you must consider your kicker, which makes twins relatively more attractive. 5. Twins with completely separate fuel/ignition sources are optimal, but cost around $3,500.00 more than singles. If you already own a serviceable kicker this is a lot of extra dough. 6. I'm liking everything I'm hearing about the E-tec. My conclusion: Unless I can confirm that Honda will add EFI to their 90, I've pretty much settled on the E-tec 90 to repower our 1991 cruiser. If I was specifying for a brand new vessel I think I'd choose twin Honda 50's. Good luck whatever you decide! Mike on Westward

[Mr. Fisherman]

I repowered from a 75 HP Suzuki 2 stroke to a 90HP 4 stroke. I went through all the same data you are. What it came down to for me was that the Suzuki 90 was the only one that would spin a 20 pitch prop. Lots of low end. I have had 4 adults, my tween son (tween = between kid and teenager ) my commercial half tote, a 150 and 80 quart cooler all loaded with ice and lots and lots of Tuna gear. The boat handeled the load awsome. I typically run heavy and like the big block of the Suzuki. It dosen't work as hard as the lighter engines and it certainly pulls it's weight. I have seen 36 MPH with the 20 pitch prop with the wind behind me headed down stream on the Columbia. I have not felt like I needed more power yet...

I hope you are as happy with your decision as I have been with mine.
I could have bought the civic on a stick for a little less money but I got a 6 year warranty and the brute of the 90HP market... imho.

I hope this helps.

[New Hampshire Guy]

WELL SAID!

As to the Honda over Suzuki in the poll, the Honda was all that was offered on C-Dorys for years. The Suzukis, new to the "Factory installed" world, will do well over time.
The 90HP Suzuki is a great engine, EFI for years, and 3 yr warranty standard with a 6 yr option.
What's not to like?

Best of luck choosing.
Fair winds...

[flagold]

"Honda was all that was offered on C-Dorys for years." That's the real truth behind it. One engine you'll never find many of on C-Dory is Mercury. Why? Because Merc is now part of Brunswick that sells their own line of boats exclusively with Mercury. Practically every other mfg will simply choose another engine rather than support their competitor's bottom line by buying Mercury. Pepsi made the same mistake years ago in buying Taco Bell, Pizza Hut, KFC in an effort to distribute their product and in the process alienated practically every other restaurant and restaurant chain in the country as they ran to Coke . . .[/quote]