15 HP, 4-stroke

[Crestliner2007]

Hello gentlemen; this 2006 engine is running fine, but with the 15' boat, which I have it on now, I'm only pushing along at about 18 mph (GPS) with 2 of us on board. At WOT, the engine is turning about 5400 rpm's (which is high for this engine). What I'm looking for, is to - somehow - increase my top end speed on this rig.

I've already "tweaked" the rig, with respect to engine height and set-back (using a Mini-Jackplate w/4" set-back); the cavitation plate is even with the bottom of the boat, at this point. I've adjusted the trim - within the confines of the manual trim bar, to optimum position, with 2 fishermen & gear onboard.

I installed a "Doel Fin", but that slowed me way down ( to 14 mph!), so I removed it. Being retired, I can't afford another 3 - 4K for a new, higher HP engine, so I'm thinking of doing something with the carburetor, if that's possible? Is there any kind of add-on or modification, which can be cost effective in increased the HP on this engine? Thanks muchly folks.

 

[JB]

Re: 15 HP, 4-stroke

There are things you could do to the engine, Crestliner, but they would definitely not be cost effective.

I think you are getting about what your engine has to give without PT&T.

I would try raising the engine and inch or maybe a little more, so the Anti-ventilation plate is 1 to 1-1/2" above the keel and see what happens.

Just keep in mind that anything you do to a non-PT&T engine to increase WOT speed is likely to interfere with acceleration. . .that includes messing with engine height, static trim, prop pitch and load distribution.

Good luck.

 

[Expidia]

Re: 15 HP, 4-stroke

The 15's a popular motor for trolling with as a kicker. So it would sell fast this time of the year.

I'd sell it on Craigslist and get a 25 if your max outboard plate allows for it.

I had the same problem with my last rig and opted to just buy another boat because the weight of the 25 would have put the egde of the transom to close to the water and the boat had no splashwell.

If money's an issue just look for an older two stroke on Craigslist which some were pretty lightweight as compared to late model 4 strokes.

There might be a carb kit to increase HP's but for what it's going to cost you to keep tinkering around, selling yours and buying a 20-25 might not be that big an investment.

 

[Crestliner2007]

Re: 15 HP, 4-stroke

Thanks for the suggestions guys!