mcdougy Posted June 13, 2013 Report Share Posted June 13, 2013 Is consistently running a 2 stroke outboard at Wide open Throttle a very bad thing? With not much boat experience, i can't decide if this is a pure sign that I need to go for more h.p. Its a 15 yamaha on 14'6" with factory floor starcraft. The boat is rated at 25hp max, I have beeen looking at some 25's, but I am a little gun shy due to the fact that I'm not looking for more speed necessarily. It is the fact to keep he boat up on the best plane I need to keep the 15hp gunnned. The other thing I'm not wanting is an overpowered boat that sticks the nose 6' in the air when you get on the throttle. Thanks for your input/experience Matt Link to comment Share on other sites More sharing options...
Pigeontroller Posted June 13, 2013 Report Share Posted June 13, 2013 2 Stroke love high rpms. Link to comment Share on other sites More sharing options...
Woodsman Posted June 13, 2013 Report Share Posted June 13, 2013 As long as your rpm's are within the spec limits when WOT than your fine running it at WOT. If the rpm's are higher or lower than the spec range you need to change your prop pitch or diameter to get it in to the spec range. Link to comment Share on other sites More sharing options...
mcdougy Posted June 13, 2013 Author Report Share Posted June 13, 2013 What apparatus do i need to find the rpm's Link to comment Share on other sites More sharing options...
Woodsman Posted June 13, 2013 Report Share Posted June 13, 2013 A tachometer. Link to comment Share on other sites More sharing options...
fishindevil Posted June 13, 2013 Report Share Posted June 13, 2013 If the boat is rated for a 25hp maximum and you have a 15hp it sounds just a little bit underpowered ??? Especially for a 15 hp Link to comment Share on other sites More sharing options...
BLOO KANOO Posted June 13, 2013 Report Share Posted June 13, 2013 Are you fishing by yourself, or with someone in the front of the boat? If you are alone most of the time you might want to put some ballast in the front to help plane it out better. Link to comment Share on other sites More sharing options...
MrSimon Posted June 13, 2013 Report Share Posted June 13, 2013 Running a properly tuned motor at WOT isn't going to hurt a thing. There are tons of motors out there that have been running that way for thirty years without a problem. With that said though, I like to back off a bit to save on gas .... it seems just slowing down a few MPH from top speed makes a noticeable difference in gas consumption. But, it does sound like your boat is a bit under-powered. A nice running 25 would put a big smile on your face for sure! Link to comment Share on other sites More sharing options...
Raf Posted June 13, 2013 Report Share Posted June 13, 2013 it's better to run a 25 at 60% then the 15 at 100% Link to comment Share on other sites More sharing options...
porkpie Posted June 13, 2013 Report Share Posted June 13, 2013 (edited) I run a 14 footer deep v utility rated for a 30hp with a 15hp outboard. I can run 19mp, and the boat will still plane with 2 guys and all gear even if I lay off the throttle a bit. I don't have floors, but have seats, trolling motor battery, gear, cooler, I weigh 230 and don't have a buddy that is less than 200lbs. Unless your hull is extremely heavy, or has a lot of interior finish like heavy floors etc, I don't think it'll be an issue. By the way, I run my Jonson at wot all the time, and frankly even when I had my lund and larger motor, I pinned it all the time. I have never had an issue, and it's never caused motor damage or failure. My old boat is still running great and a buddy owns it! I use premium amsoil synthetic, and all my 2 stroke and 4 stroke power equipment purrs like a kitten! Edit to add, I also have a starcraft. Figure out what your floors weigh, and take it into consideration! Edited June 13, 2013 by porkpie Link to comment Share on other sites More sharing options...
Roe Bag Posted June 13, 2013 Report Share Posted June 13, 2013 (edited) Is consistently running a 2 stroke outboard at Wide open Throttle a very bad thing? With not much boat experience, i can't decide if this is a pure sign that I need to go for more h.p. Its a 15 yamaha on 14'6" with factory floor starcraft. The boat is rated at 25hp max, I have beeen looking at some 25's, but I am a little gun shy due to the fact that I'm not looking for more speed necessarily. It is the fact to keep he boat up on the best plane I need to keep the 15hp gunnned. The other thing I'm not wanting is an overpowered boat that sticks the nose 6' in the air when you get on the throttle. Thanks for your input/experience Matt You can't harm an outboard running it within the WOT perameters. Standard props (supplied with the engine) are designed to keep you in that range. All outboards are designed to be run between 5000 and 6000 rpm. Exceeding 6000 will result in over reving and a blown powerhead. Below 5000, your engine is struggling. This can result in premature bearing wear, ring wear, or burned valves. If the boat suits your needs, then there it is no need to repower with a 25. A 25 at 3/4 throttle will probably burn more fuel than your 15 at full throttle. A 25 hp will not make your boat stand on end on takeoff. It will increase your top speed slightly. It will definitely increase your load carrying capabilities. Your 15 two stroke probably weighs under 100 lbs. A 25 two stroke weighs 114lbs. A 20 four stroke weighs 114 lbs. The 25 four stroke weighs 181 lbs. Extremely heavy. If you go with a 25 four stroke you should definitely have a 20 " transom. Been running two strokes wide open for over 50 years and never had a problem. Long before the advent of synthetic oils! Hope this helps. Edited June 13, 2013 by kwikfish Link to comment Share on other sites More sharing options...
jimmer Posted June 13, 2013 Report Share Posted June 13, 2013 You would love a 25hp on that boat. Link to comment Share on other sites More sharing options...
Sinker Posted June 13, 2013 Report Share Posted June 13, 2013 2 strokes run best at high rpms. Bogging them down at low rps will cause more harm. S. Link to comment Share on other sites More sharing options...
krixxer Posted June 13, 2013 Report Share Posted June 13, 2013 (edited) oops Edited June 13, 2013 by krixxer Link to comment Share on other sites More sharing options...
mcdougy Posted June 14, 2013 Author Report Share Posted June 14, 2013 The boat only weighs 400lbs. WOT she runs about 18-19 mph according to the hbird. Link to comment Share on other sites More sharing options...
mcdougy Posted June 14, 2013 Author Report Share Posted June 14, 2013 2 strokes run best at high rpms. Bogging them down at low rps will cause more harm. S. There is some bog/lag when you give her the smack of throttle to achieve plane. Once it starts to grab it gathers rpms and away she climbs. The 15hp is running perfctly imo also, thiking it is the weight thing. I guesstimate boat ,motor, gear, gas, and me at 800lbs at least. Link to comment Share on other sites More sharing options...
porkpie Posted June 14, 2013 Report Share Posted June 14, 2013 The boat only weighs 400lbs. WOT she runs about 18-19 mph according to the hbird. Sounds about right, I wouldn't change a thing unless you have a need to go faster! Link to comment Share on other sites More sharing options...
Roe Bag Posted June 14, 2013 Report Share Posted June 14, 2013 The boat only weighs 400lbs. WOT she runs about 18-19 mph according to the hbird. My previous boat was basically the same weight. Solo with all my gear it ran 23 mph with a 25 two stroke yamaha. Two guys and our gear and it fell of to about 20 mph. Three guys and our gear it was in the 17-18 mph range. An inexpensive tool in monitoring your rpm is the tiny tach. Cost about $60 and can be a big help in selecting the correct prop for your specific application. It is also an hour meter and can be useful in keeping track of 4 stroke oil change intervals. When the engine is running it indicates rpm. When the engine is stopped it shows the engine hours. A handy gadget! http://tinytach.com/tinytach.php Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now