Replacement motor and options advice please

R

RMH

Member
I have a older model (early 80's but in good shape) 17.5 Double Eagle. It currently has a 70 horse Evinrude and a 6.0 horse Johnson, both 2-stroke, both running and gas guzzlers. I have 2 portable 5 Gal tanks that I must pre-mix and pack in and out of boat. With this set-up I have no range. Am considering replacing both motors with new 4-strokes. Likely Honda or Yamaha. Should I? If so what size is appropriate? Would it be possible to install built in tank? Is that an option?

Any ideas or suggestions would be appreciated. Thanks.
 
Hey RMH,

Also a DE owner 17ft we have 115 tammy but she's back heavy I'd recommend going with a 90. make sure you check the boats max HP size as they might be different. my DE was early 90's.
 
Had a 17.5 DE and had a 100 yamaha 4 stroke on the back of it. I always thought it did sit a bit low in the stern when in the water. The new 90hp is essentialy the same motor.
 
If you are going to go to a heavier 4 stroke you should open
P the floor and put in a built in tank up forward between the seats to balance the weight distribution so it doesn't end up squatting in the butt end. Not sure how much room there is between the sole and hull on your model. I would phone the factory for advice on that.
 
Don't go past 90hp in that hull in 17.5. I have the 16.5 DE they already sit stern heavy and 60 hp is plenty of power. The in floor tank is a good option.. A lot of DE have old ratings based on old two stroke outboards not four strokes...

In that boat if it was me I would run a 90 hp e-tec which is much lighter and a four stroke kicker. My 16.5DE has a 60 hp two stroke and a 8Hp Yamaha T8.... That's the max weight I can pretty much put on I found..
 
profisher said:
If you are going to go to a heavier 4 stroke you should open
P the floor and put in a built in tank up forward between the seats to balance the weight distribution so it doesn't end up squatting in the butt end. Not sure how much room there is between the sole and hull on your model. I would phone the factory for advice on that.
Click to expand...
The weight issue between 2s and 4s is less and less each year as they shave more weight out of 4 stroke motors. Presently the lightest of the "big 5" in 90 h.p. is the 2 stroke Etec evinrude at 326 lbs. Next is the 4 stroke Suzuki at 348, the Honda (all 4 strokes) at 359 and the yamaha at 372. The heaviest is the Merc (as usual) at 400 lbs. These are dry weights and do not include the weight of leg oil, engine oil in a 4s or a oil mix tank in a 2s. (these weights are almost a wash). Should you make your decision on 2s or 4s based on 40 lbs. of weight in the stern? not sure it would weigh my decision, but it may make a slight difference in trim when not on plane. It would make almost no difference in a 17.5 DE when up on plane.

The advice about a center tank is bang on. Lowering the COG (center of gravity) and moving all that weight forward and to the center of the boat will improve the handling and make trimming the motor much easier. If you can't utilize the hull below the floor, then a bow tank would also be a good option. It is also much easier when both your motors are on the same tank. You do run the risk of contaminated fuel stopping you dead. compared to two tanks from different fuel sources, but I consider this to be a really really small risk.
 
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Make sure the boat will fit your needs for several years, as you are looking at a rather expensive refit.
A new 90hp and and a kicker will likely set you back 15K + taxes.
camp returns could be an option that might save you some money.
check out SG Power and Bridgeview marine.
you will be happy with the fuel savings for sure.
 
Well I was looking at repowering.... I have a 90 two stroke Yamaha if I went with the same vintage and just replaced with a 115 add 100 pounds. If I wanted to go 90hp 4 stroke new add 100 pounds. Weight is a big issue. But the one thing I have figured out I'll never replace my Yamaha with another Yamaha. I wanted and ETec but leaning towards buying a Mercury. Just don't have the $16,000 to do the mods I want to add with the new motor.

If I was to pull the pin today I'd be doing a 18inch haul extension... Not a pod...and a brand new 115 Poptimax

The issue is weight when repowering these older boats.... Good Luck,
 
r.s craven said:
Make sure the boat will fit your needs for several years, as you are looking at a rather expensive refit.
A new 90hp and and a kicker will likely set you back 15K + taxes.
camp returns could be an option that might save you some money.
check out SG Power and Bridgeview marine.
you will be happy with the fuel savings for sure.
Click to expand...

One thing to keep in mind is that for a lot of manufacturers, a 90HP and 115HP four-stroke are basically the same motor, same powerhead; usually just the intake or exhaust is adjusted to lower horsepower on the 90HP. So if you find out your boat is safe weight-wise for a 90HP you can consider a 115HP - lot's of 17 footers have 115HPs, rigged many myself. But a 90 will work just fine too. This isn't always true for 2-strokes; Yamaha's 90 was a 3 cylinder and the 115 a 4.

Like Craven said, you are looking at an expensive re-fit. Consider your long-term plans and general needs on the water before switching - it's gonna take a lot of gas savings before the cost equals out! IMO, I'd probably just run them both until they die, unless the range issue is a big factor for you.
 
If you like the boat and it is real sound ........ Cut the motor well out ......glass the full height transom .... Pod it and put a 150 used motor on it. Ready to rock n roll
 
Rather then cutting into the floor and installing and plumbing a fuel tank, you could look into putting one in the bow of the boat. My cousin had a 100L aluminum tank welded installed and fully plumbed in the bow of his 17 foot hourston for under $500, and the bow still has lots of storage for life jackets, prawn puller, riggers etc.
 
I have a 1998 Double Eagle 176 with a build in 99L tank which is in the back floor the space between is seats is my fish locker. I also have dual batteries and a 8hp Johnson kicker plumbed to it's own 5L tank which seats in the back as well. My main is a 150Hp etec. I fish on the inside in good weather mostly and my engine well rarely has water in it even with 2 guys netting a fish it's mostly dry it's really a none issue.

Like I said mines a 1998 and I know they changed the design at some point but mines great.

boat.jpg
 
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I put a 32 gallon bow tank im my old 17.5 which really changed how it rode. All for the better except it made it realy hard to get off the trailer.
 
The new Yamaha F115b is lighter than previous model and has troll control allowing 50 rpm increments from 600 to 1000 rpm , nice motor and one throttle body instead of four , also has a bigger displacement over 1800 cc
 
jaymasta said:
Rather then cutting into the floor and installing and plumbing a fuel tank, you could look into putting one in the bow of the boat. My cousin had a 100L aluminum tank welded installed and fully plumbed in the bow of his 17 foot hourston for under $500, and the bow still has lots of storage for life jackets, prawn puller, riggers etc.
Click to expand...
Have a 16.5DE that i'd thought of doing this to as,yes,it's a tad heavy in the stearn. PM sent,jaymasta.
 
had an older de like yours with a 150 on it no problems with handling for 6 years steady fishing,you can buy a large portable tank that will fit between the seats at west marine
 
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