Thinking of replacing 85hp Force with 70 hp Yamaha

[Mark42]

How do you think a late model 2 stroke Yamaha 70 hp outboard would perform on my 16' Bayliner cuddy/hard top in place of the 1985 85 hp Force that is on it now?

Thinking of getting a newer motor, and knowing that the hp ratings were different between the 1985 year Force and newer model motors, I'm wondering if the new 70 hp motor would be equal to my aging Force. The Force has 110 psi on all cylinders (iirc). A little low, but even.

I like the 3 cylinder Yamaha motor because it weighs less than many similar size motors by Johnson/Evinrude (like the 90 hp models).

I don't really care if I loose 5-7 mph top speed as my intent is to get a newer motor that will be more reliable, parts are easier to get, has power tilt/trim, and is not smokey at no wake speeds.

Suggestions for light weight 70-90 hp late model o/b's, say 1990-2007, that you think would make a good replacement are appreciated.

Thanks!

 

[coolguy147]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

evinrude johnson 3 cyliner looper? 70-75hp right?

thought they had the best in power to weight ratio.

 

[tx1961whaler]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

evinrude johnson 3 cyliner looper? 70-75hp right?

thought they had the best in power to weight ratio.

1985, 85 HP Force = 249 lbs.
1995, Evinrude E70TLEO (w/tilt and trim) = 237 lbs
1995, Yamaha 70TLRT (w/tilt and trim) = 223 lbs

 

[Mark42]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

evinrude johnson 3 cyliner looper? 70-75hp right?

thought they had the best in power to weight ratio.

I was looking for the specs for the Johnson 70-75 hp to see how much it weighs, but couldn't find a weight. The 85 hp Force weighs about 275 lbs, so I'm hoping the Johnson/Evinrude will come in less.

Got a spec on the jonnyrude?

EDIT: OOPs! Tx1961Whaler, you beat me to the post! Thanks for the weights!

 

[tx1961whaler]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

The weights and stuff can be found here if you want to compare other motors:
http://www.nadaguides.com/default.a...50636&l=1&w=24&p=38&f=5693&gc=mr&gtc=ob&any=0

 

[ezmobee]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

Mark, didn't Yammie make a sweet 3 cyl 90HP? I would think this would be ideal

 

[cougar1985]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

if your thinking new as in brand new dont rule out the f70 yammie (4stroke) the weight is fantastic compared to the compatitions fat slugs.its about 100 plus pounds lighter than most.it weights 260lbs.lighter than all manufactures 4 or 2 strokes of similar hp (new).seriously thinking of that one for my boat .

 

[Mark42]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

if your thinking new as in brand new dont rule out the f70 yammie (4stroke) the weight is fantastic compared to the compatitions fat slugs.its about 100 plus pounds lighter than most.it weights 260lbs.lighter than all manufactures 4 or 2 strokes of similar hp (new).seriously thinking of that one for my boat .

From the specs I see, in 2004 (typical) the 2 cycle yamaha 90 (3 cyl) weighs 260 lbs, the 4 cycle (4 cyl) weighs 370 lbs. The same year Johnson 2 cycle (4 cyl) weighs 335 lbs and the 4 cycle (4 cyl) weighs 421 lbs.

So, the 90 hp 2 cycle yamaha has a weight savings of 110 lbs over the johnson 2 cycle 90 hp, and a 90 lbs weight savings over the 4 cycle johnson.

Yep, those numbers are impressive. The 85 Force weighs in at about 250lbs or so, depending on what spec you reference. So the Yamaha would be the best weight match. Its probably also about 15 hp more than the old Force, due to the difference in HP ratings between 1985 and 2004, plus add another 5 to 10 hp for compression loss, and the 90 hp Yamaha would be a real kick.

Plus the coast guard sticker in the boat lists the max motor hp rating at 90, so the Yamaha just squeaks in.

 

[jasonbailey]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

I did somewhat the same as you last year. I replaced my 75 HP Chrysler with a 90HP Mercury. I too was sick of the smoke at low speed/idle, manual tilt, and afraid of dwindling parts availability.

My boat is a 18' tri-hull with a just over 6' beam. The 90 will push it at WOT 38 MPH with 2 adults and 2 kids, and 24 gallons of fuel. I would suspect your boat with a 70 would be right around 30-35MPH with a 70.

The Yammy's are nice, you see them everywhere. I don't think you can go wrong with one.

 

[trendsetter240]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

Suggestions for light weight 70-90 hp late model o/b's, say 1990-2007, that you think would make a good replacement are appreciated.

Thanks!

Johnson/Evinrude 70HP, 3-cyl are an excellent motor. They are very popular and parts are very easy to obtain.

93-95 are the best of the old-style 3-cylinder loopers from J/E. 96 and later are basically the same design but come with newer electronics and include the system check in the controls.

The 3-cyl carbureted 70hp's are all very light 230-250 lbs. Once you get into the year 2000+ models with direct injection they get heavier.

My 95 Evinrude 70hp pushes a fully loaded, 2000lbs (including people and gear) 17ft runabout at 33mph WOT.

 

[Mark42]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

Great info guys.

The aging 85hp pushes the Bayliner to 35 mph (by Feria petot speedo) with two adults, two kids and 17 gallons of fuel and gear w/hard top. Best speed was 38-40 mph with me, 6 gallons fuel, and the hard top was not on.

If a "fresh" 70 hp Jonnyrude will give about 35 mph with a moderate load that would be great. I can find the 70 hp easily.

A 90 Yamaha would be great too, but they are harder to find used and in good condition. People just don't seem to want to sell them.

Motors are harder to find now than ever. Nothing to speak of on ebay (and I don't think I would buy from ebay anyway), and even the pickings on craigslist are not so good. Take a look at iboats outboard motor list, and its rather absent of used motors. Most all of them are brand new. Last season they had 5 o 6 used motors in each hp group.

So I'm keeping my eye out. Even called 1outboard.com and they didn't have a yammy, but he did have a 70 johnson complete rebuild that I might call back about.

 

[ezmobee]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

Since your Force is running well, I'd hold out till I found a Yammie 90.

 

[Mark42]

Re: Thinking of replacing 85hp Force with 70 hp Yamaha

Since your Force is running well, I'd hold out till I found a Yammie 90.

Running well, yes. But overall condition is not the best. Last night I finally got the thermostat cover off (the thermostat was hanging up in the closed position making the motor overheat). "Only" broke one screw. The other three finally were persuaded to come out in one piece. So now I have 3/8 of threaded screw sticking out of the head I just can't budge even when applying heat. And the impeller is on its way out, the tell tale dropped off quite a bit in its stream this season compared to last season. And the throttle linkage broke, and I'm not sure I can find the right size roll pins (aka tension pins) to fix it. Picked up 3/16" pins last night, and they might be too big. Could be 1/8", but I have to drive the remains of the old pins out first to be sure.

So the motor runs well, its the supporting systems that are messing up. Probably can get through the rest of the season with new impeller, new thermostat and fixing the linkage. 2 and 1/2 weeks to go before I'm on vacation again, so I am working hard to get this motor running.

I would prefer the 90 Yamaha, but a fresh rebuilt 70 Johnson might get the job done too, just not as fast to plane and lower top speed.