mako 171 repower questions

[circlehook17]

1988 171 special? I have a 1996 merc 90 on the boat now.I guess i'm concerned about weight of 4strokes.My merc is about 305 lbs,zukis 90 and 115 weight 427 lbs, yam 90 369 lbs, 115 402 lbs.What are your recomondations or experience with these 4 stroke weights on the 171

thanks guys[]

[Greene]

I guess it is really matters how close your scuppers at to the water line. I would take some heavy freeweights, try to borrow some 45 pounders from a buddy if you don't have any, a place them on the transom to see how it fairs. I would also go at test with at least 50-75 extra then the weight of 4 stroke. You want to do the test as if you have a full load.

[michigan dave]

Great idea Greene, sometimes the simple ideas are the best. And in my life I need things simple[;^)] dave.

[greg mako tmbc]

Circle,

I've water tested or sea trialed at least a couple dozen 171's with just about every power option available. F.E. When you get to the Merc 115 4 stroke which weighs 386 lbs.,trim tabs are a forced option if you were to buy a new boat.

Since the 171 is one of our shallowest running Makos w/ a 9" draft, time to plane with a conventional 4 stroke keeps your prop in the danger zone that much longer. Maybe consider a DFI 2 stroke, In my experience they provide your boat the best performance. The 115 optimax at 375 lbs. will give you the low end tourque the 4 strokes lack, while still giving you great fuel economy.

[100th meridian]

Experimenting with the free weights is a good idea to see how the waterline and scuppers will be affected. By going with a 4 stoke you are adding about 10% to the weight of your mako and it is all on the transom. That is quite a bit especially if you have a couple mates on board. If the battery is not under the CC you may want to think about moving it to help distribute weight. When I was shopping for new power I decided to go with a 2 stoke on my 20 mako because the the weight this was advice I got from the wrench who installed the motor.The smaller older boats like ours were not designed to carry todays new 4 stokes particularly near the upper end of the hp range. Made sense to me. The new 2 stokes are pretty fuel efficent, have good torque and are very clean compared with the older ones. With the 3 grand or more you'll save on the the 2 stroke you can use the difference to buy that 1000 + gallons of fuel. That abot 30 fill ups for your 171

[corpuscruiser]

The Suzuki 140 4 stroke weighs 415 lbs or about 40 more than the 115 optimax. The Suzi has a higher HP to weight ratio and is a great engine. I have it on my boat and the only time I notice a problem is when we're achored with 2 guys in the back. And the problem I have is that I get just a LITTLE bit of water in the scuppers, not even enough to get your feet wet three inches past the transom. Otherwise, no problems with the 415lb engine.

[mubikS]

I originally had a 1985 Suzuki 75 on my boat, and it pushed the boat to about 32 WFO, about 27 cruise. Boat age seems to affect where the scuppers are just as much as weight in the stern, because even with that 75, which only weighed 270lbs, the scuppers were underwater.

I sold the 75 this summer and dropped on this 1995 Suzuki 140, which weighs in at 370lbs. I now go 41 WFO (with just me on the boat, or 5 people... only time to plane is affected), and cruise easily at 30mph and 3500 rpm.

The boat actually seems to sit level on the painted waterline with the 140, as it used to appear to be light in the stern with the 75 on it.

Having the scuppers below the waterline is not necessarily the end of the world. Pain in the ass? Yes. I just popped on one of those ping-pong scuppers and make sure it stays clean of debris.

Go with a motor that will have the power you need. That 140 damn near pulls my arms off when I'm skiing. []

[circlehook17]

Thanks for the info,I dont think my scuppers would be of concern.Going from a 305 lbs 90 merc to a 369 lbs 90 yamaha.Im just trying to get some info so when the day does come i need to repower.Placard says boat max hp is 135. Even in 1988 an engine that size had to have some cosiderable weight. thanks again guys

[mubikS]

Holy cow that's one heavy 90! [:u] Did you say that's a 4-stroke? In 2004, the 4-stroke was 370 and the 2 was 261. That's a big diff!

Are you set on the 4-stroke or would you consider a larger 2-stroke?

[cgmiller]

I recently replaced the 1983 90 Evinrude with a 1991 115 Merc for my 1974 17CC. The Merc is about 40 pounds heavier than the Evinrude was. I moved the battery from the starboard fish box to under the consol to move some weight forward. I have installed new scuppers in the transom and need to put 3 5 gallon buckets on the bow to get her to drain. I had to do the same with the 90 and the battery in the back, so it is pretty close. Performance wise, the 115 runs about 5 mph faster than the 90 at the same rpms, but that is due to fact that it is spinning a 19 inch pitch prop instead of a 17". Cruise at 4000 rpms is 27/28 mph, 32 at 4500. WOT is about 36 mph at 5500 rpms. If you look at the perfromance bulletins for 17-18 foot CC's, there is not much difference between the 2-strokes and 4-strokes in fuel efficiency. Biggest difference is not having to use oil. But the cost of the 4 over a 2 pays for a lot of oil.

[stuartmark]

Anyone with a Suzuki/Johnson 140..., I'm looking at a 140 Suzuki to repower my '96 171, currently has 135 Merc. Problem is my boat nameplane has rating of 135HP. If yours was same did that present any problem with finding someone to mount it, insure it? Do you know if its legal at that rating? BTW, what do you get at WOT. I now get about 44, but burn at least my share of fuel doin it. Any advice is appreciated.

[mubikS]

stuartmark,

The 140 will work fine. I know of 150s (and up to 225s) going on these boats. There is nothing illegal about exceeding the HP rating on the plate; it's just a CG recommendation.

I mount all my own motors. Before I bought my cherry-picker (engine hoist) I just used a come-along and a chain hung from a tree. There's not really anything technical about it. As for insurance? I'm still working on getting mine insured, but they've only given me a hard time about the hull age, not the HP.

I top out at just over 41, with a 19" prop. I probably could go to a 21 or 22, but I prefer the hole shot.

[mako224]

Its not illegal but it does open the door to litigation should an unfortunat incident occur. It could also be an issue when you go to get an insurance policy.

[corpuscruiser]

I like my 140 and my CG plate does say 135. I've hit a GPS 42 at WOT (6100 rpm) before, but that was alone, flat water, a slight tailwind half a tank of gas, 20lbs of ice and three redfish ;-) I usually run in the low to mid 30s at 4200 - 5000 rpms cruise. I'm using the Suzuki 3 bladed stainless prop - 14 x 20.

[mubikS]

Corpus, what year is your 140? Is it a 4-stroke? 6100 seems awful high.