2008 90 hp 2 stroke on a 16' Smokercaft Pro Mag 162

Joined
Oct 6, 2015
Messages
5
I just bought a boat, it is a 2008 16' Smoker craft Pro Mag 162. Dry weight is 1,020 lbs. It is rated for a 90 horse power motor maximum and has a 2008 Yamaha two stroke 90 motor. I took it out and it is amazingly sluggish out of the hole. Motor runs great but seems to spin up slowly. It also has some trouble making it over onto plane. Rides a long time with the bow way up in the air. If I move weight (my wife) on the bow it comes to plane much more quickly. top speed was about 35 mph fully loaded and trimmed out at about 5000 RPM. I expected a totally different experience. It came with two props a black one that is installed with these numbers stamped on it: 101U34 and Y13X19 and a white one not installed with these numbers: 13 1/4 X 17K and 17Y, Y-3, 6E5 stamped in other places. I have installed a small hydrofoil which came with the boat but was not installed, but have not tested it again. I would appreciate any thoughts or advice.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
I run a 13-1/2 X 17 prop on my Yamaha 2 stroke C90 on my 18 ft. Ft. boat and it'll snap up on plane in 4 or 5 seconds regardless of load....so I'd say you may have a problem with the motor height, set-up or trim....or could be your power is down from low compression or dirty carbs or other issues with motor....
 
Joined
Oct 6, 2015
Messages
5
I wondered about problems with the motor too, I should have put that in the original post. I bought from a guy who hadn't run it in two years. And took it to the local marina for a tune up and got a clean bill of health along with new plugs. I'll check motor height today and post that data. Thanks Robert.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
You really should be seeing about 5500 RPM wide open throttle trimmed up.....if motor, prop and set up is correct....maybe pop that 13 1/4 X 17 on there and see how it does...might make a big difference!....Your boat/motor should be pretty darn peppy....
 
Joined
Oct 6, 2015
Messages
5
Thanks Robert, I was wondering about that as well. I if I understand correctly the lower pitch prop should give me higher top speed and a little higher RPM. But I also thought it would be worse getting onto plane, I would hate to make that worse. I'm planning to test it with the current prop on with the hydrofoil tomorrow night, then switch the prop and try it like that on Friday. I looked at the height of the motor last night, and it looks to me like the lower planeing surface is about 1/2 inch above the bottom of the boat. I have attached a couple of pictures.
motor height.jpg motor height1.jpg
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
It may be that prop...wonder why previous owner had 2 different props anyway?....I believe that 13 1/4 X 17 is the one you want....it must be something because the 90HP Yamahas are not known to be "sluggish"....
 
Joined
Oct 6, 2015
Messages
5
I took it back to the marina this morning for a river test, we will see what they say, but the more I think about this the more I think you might be right, I just can't imagine why the previous owner switched out the prop. We will test and see what we can do. Thanks for all your help, it's good to have someone to talk through these issues with.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Water or wet foam in rear/bilge area of the boat could also cause sluggish planing/performance....check for water in rear of boat...
 
Joined
Oct 6, 2015
Messages
5
I looked everywhere for water everything seemed dry, but I haven't checked for wet foam. Boat has always been stored in doors, but I'll see if I can find a way to check that too.
 

mdunn

Petty Officer 2nd Class
Joined
Oct 7, 2007
Messages
186
Hey There Scott from WA.
As others have said try that 17 pitch prop.
Then go out in flat water and see where you're RPM's are at WOT.
What I say now is based on my knowledge of my FOUR STROKE Yammy 115 so
I don't know what ideal top RPM is on that 90 2-stroke.
In my case once I had the height correct in relation to the keel I was able to run WOT and confirm I had 5800 to 6000 RPM which is what is recommended.
I bet with that 17 pitch prop you'll be spinning up closer to that RPM but you need to verify what your engine WOT RPM should be.

THEN I would recommend ditching the hydrofoil you have screwed on and buy a set of Smart Tabs from these guys.
http://www.nauticusinc.com/smart_tabsSX_automatic_trim_tabs.htm
I have them on my 17.2 Smoker Craft and it's been night day in terms of making the boat handle so much better and pop up on plane so much faster.
Before I had them too many times I stood that light weight/max powered boat on it's stern and it was kind of scary sometimes.
I do 43 mph at WOT per my GPS on nice flat water.
You play here in Puget Sound?
You'll love the way those Smart Tabs handle going through the typical chop we get.
Good Luck!
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
7,985
Hello my dad has had a 1985 90 yamaha since new. Here is what we have found the low end power of these is not great they have a much better midrange and top end. Years ago bass and walleye boats did a 90 hp shootout that motor on a dyno put out 81 hp at 5500 rpm and 91 at 6000 rpm. Keep it propped to be at 5500 rpm with a full load and watch overreving on a light load. What you get from this motor is a great running incredibly reliable outboard that will last forever and run better than most engines out there. Another thing we noticed is it does not have as much negative trim as say evinrude or mercury which does not help holeshot.
 
Last edited:
Top