18hp to 25hp

[82rude]

Re: 18hp to 25hp

i found a 69 brochure and they have as a optional prop for your motor 9x9p.the one you have was the standard prop.im not in the lest disagreeing with howard as for 3 big guys and gear a 8p might be correct but the only way to know for sure is to hook up a tiny tac and check rpm,s at wot with the gang along as he suggested.remember the more people and gear you stuff into a boat with a small motor the more they dont like it as their only small motors and it doesnt take much to upset them.

 

[870 Expressmag]

Re: 18hp to 25hp

Well we rarely have 3 people in the boat, only on no wake lakes where trolling is the only thing allowed. Most of the time there's only 2 adults. I got an actual weight on that ballast that was under front seat, it's 86lbs. I bet having that removed it will make a difference. Dad and I are gonna try and go get a tach reading before it gets to cold

 

[richardgreen]

Re: 18hp to 25hp

My $.02, I'd pass on this one. Wait to find a 25-35 hp model from '84 or later after the hp ratings method changed and had the thru hub exhaust. I think you'd be much happier in the end. Good luck.

RG

 

[pootnic]

Re: 18hp to 25hp

86lbs is alot of weight to remove,on a small aluminum boat.
The guy probably had it up there because he boated along and helped the boat plane off?
Have fun boating and hope that helped.

 

[870 Expressmag]

Re: 18hp to 25hp

Yes he told me he put it up there to keep the nose down when by himself, I don't go by myself a lot so I removed it, hope it helps, will try to get a tach reading soon

 

[82rude]

Re: 18hp to 25hp

86lbs. ! wow, you basically had another 18 evinrude in the front.

 

[steelespike]

Re: 18hp to 25hp

The 18 is capable of 27 mph on a light reasonably fast boat. Years ago I made an indicated 25-26 routinely on a big 15 foot kit boat. Your prop looks a little beat up I think a new 9" pitch will
make a big improvement. The boat seems a good size and should handle weight well.
Move the gas tank forward; thats 35 or 40 lbs you don't need in the back.
The anti vent plate( just above the prop) should be about even with the bottom.Motor trim adjusted carefully .
Trimming in(prop closer to the boat) makes it easier to plane and will stay on plane easier though top speed may be
less. Trimming up(prop away from boat) may slow hole shot and fall off plane easier but could make more speed.
Too much up trim could create you're problems.

 

[cyclops2]

Re: 18hp to 25hp

Might help if you have someone in another boat or on a dock to watch you go by @ WOT. HE can see if the motor is truly vertical at wot .
You stop move the tilt pin. Couple of passes did it for me. I was wrong when I moved it around guessing. No GPS needed. Straight up is up.

You may want to do the same tests with the 2nd person on board. Mark the holes with 1 & 2.

 

[870 Expressmag]

Re: 18hp to 25hp

well the trim has been mentioned to me by a guy that used to work at a marina. i was going to try that as well, but didnt wanna change to many things all at once so i could narrow down the actual cause, of course maybe it's a bunch of little things causing the big problem. The 86lb weight has been removed. i wanna get out with current prop and tach the motor and see where i'm at, thats probably all i will get done this year as i'm in michigan and the fowl weather is closing in fast. As far as the trim the motor has 4 holes, i have it set in the 3rd from the boat which steelespike indicated could be part of my problem as well

 

[870 Expressmag]

Re: 18hp to 25hp

well dad and i made it out last night after work just enough to get a little info. I left the trim the same as before, and everything in the boat was as normal (anchors, fuel tank, oars, fishing gear etc.) the 86lb weight was removed from under front seat. i am 310lbs and i was in rear seat driving tiller steer, dad was in middle seat at 220lbs. the lake was smooth as glass. the nose ran noticeably higher, obviously. acceleration and speed werent to bad. and it ran on plane very well. dad even moved up to front seat and we maintained plane, also when he sat up in front from dead stop the boat came up on plane nice and easy. However at WOT we tached it at 4600 rpm. isnt this motor supposed to be propped for 5000-5500rpm? so now i am thinking with a 9 or 8 pitch prop and the removeal of the 86lb weight i should be good to go with this motor. Only other thing is pitch, i left it where it's always been, in the 3rd hole from the boat out of possible 4. however i did notice last night that the motor does not sit straight up when motor is on plane, it seems tucked under. i did take a short video of it running last night i will upload when i get home.

 

[82rude]

Re: 18hp to 25hp

where you have the pin sounds a little confusing.starting from the bottom pin where are you?try going 3rd hole up from the bottom .

 

[870 Expressmag]

Re: 18hp to 25hp

thats where the pin is at. Starting at the lower hole (closest to the boat) i am in the 3rd hole up out of a total of 4

 

[870 Expressmag]

Re: 18hp to 25hp

not sure this will help with anything, but i shot this last night with my iphone, not the best video but i was trying to drive too, shroud was removed because the wire to my tach was giving me erroneous readings, so i unplugged it, removed the shroud and held it up to coil wires and that gave us the 4600 rpm at WOT

 

[webrx]

Re: 18hp to 25hp

if Dad in the front made it plane better, it sounds like you may need to drop it down to hole 2 to me (second from the hull) and see if that makes it better with dad in the middle (if that is where he normally rides).

d

 

[pootnic]

Re: 18hp to 25hp

Doesn't seem to bad to me.../
Sounds okay,your tach could be off a bit,who knows.
It's an 18hp,on a 15' boat,with acouple good size fellas,plus gear.
You could play around a bit,different pin settings,shift some weight around maybe a new prop but I don't think your going to do much better then that looked.
Have fun and enjoy...maybe something alittle bigger(hp)will be in the cards at a later date.

 

[kfa4303]

Re: 18hp to 25hp

It looks and sounds good to me. Pretty much, just like my '66 20 hp, which essentially the same motor. I agree that fiddling with the tilt/trim and motor height may hep a bit too. I'd say anything +/- 20 mph is pretty good for these old 18-20 hp. 27 mph is awesome and probably the absolute max. for these old gems. I love my 20 hp, but I'm getting some 10 hp-itis as well

 

[steelespike]

Re: 18hp to 25hp

I noticed a little stutter as you opened the throttle.The idle mixture might be a little rich.
Lean it a little at idle in gear moving.Get it smooth and leave a tiny whisker toward rich,not enough to affect it.
With your 310 lbs in the stern seat i think your hole shot is pretty good.Wouldn't hurt to try to raise the motor some.
Just put a stick on top of the transom to hold the motor till you tighten the clamps.
just keep it so the clamps have a good grip.Be sure it pumps water.
by the way the original brochure indicates 18hp at 4500 rpm with a 4000-5000 rpm range.
I think your propped pretty good. And a new prop the same size should help.
If you go down in pitch you'll gain some rpm and a little hole shot may stay on plane easier at reduced throttle but may trade off some top speed.

 

[kfa4303]

Re: 18hp to 25hp

You can also try using a tiller extender that will allow you to move forward as need, which may help you get on plane a bit more quickly too.

 

[EddiePetty]

Re: 18hp to 25hp

Deleted......failed to read previous post.