40 Merc

[LaAngler]

also, power trim adds a few mph

[Opinions_Vary]

What is a reed? Can you do all the same things to Yamaha motors, I have a 50 on a 16 ft that doesn't push the boat much over 30mph.

[Ray]

Reed is like an intake valve on a 4 stroke.
It lets air/fuel mixture into the engine but doesn't let it flow back into the carb.
It is used an a carb'ed engine for sure, but not sure about the newer fuel inj. engines.

[Opinions_Vary]

Where do you find performance mods for boat motors?

[Dink]

You can get the carbon fiber reeds for almost any motor.......2strokes aren't all that efficient. .......they're supposed to help.....

[lapipeliner79]

want to trade a 07 camo 1648 vflat with a tunnel for a narrower boat

[LPfishnTIM]

my boss had a 1442 jon with a 40 merc with tilt trim, jackplate, 2 people 53mph! boat rated for 25 had reinforced transom thats crazy for a small boat,
If I had a 40 wanted more speed, I'd get a prop with a progressive rake and some cup on it, some disadvantages is can't haul as much weight which doesn't matter if your bass fishing with a few rods and a few pounds of tackle,

[Dink]

Yo!

[lapipeliner79]

what up dink

[joshdomingue]

Originally Posted by 2ndamendment

Those 3 cylinder 25 Suzuki's are darn near bullet proof.

my uncle has one on 15 ft alweld and it runs about 35!!!!

[Raymond]

Originally Posted by Natural Light Kid

I know I'm about to open a huge can of worms. I bought one of the good old Mercury 40's that everyone claims runs anywhere form 40-99 MPH. I put it on a Southfork 16x46 flat bottom with a jackplate. Same set up with my old 25 Suzuki would run 30 +/-. With the 40 it's running 35+/-. According to everything I hear, it's hard to get those motors to run under 40 MPH on anything. I have
my jackplate set up so that I'm on the verge of blowing out so I don't think I can come up any higher. It is a stock motor with stock carbs. I had the carbs cleaned a couple of months ago when I bought the motor but could it be possible they are not in sync, adjusted right, etc.? I have a tach and I'm only turning up about 5200 RPM. The prop is stamped 14 pitch and does not appear to be altered.

NLK, I reread your post and I think you are trying to run to high on jack plate. Try lowering jack plate 1/2" and GPS, mark location with a sharpie. Make notes of speed at each new mark, when you are done you should have a pretty good idea of where the motor will preform best on the boat.
40 mph should be an easy number on that setup to achieve without mods.

[Ray]

Originally Posted by joshdomingue

my uncle has one on 15 ft alweld and it runs about 35!!!!

Them engines run great, but the tiller handle and motor mounting brackets break too easy.

[RickyH]

I have a stock 06 4stroke 40merc on a 20x36 tunnel hull that runs 36mph on gps. That is with just me in it and I have no jack plate. Not sure what pitch prop is on it.

[southern151]

I pull 30-32 mph with my 40 Merc with two men onboard. No jackplate and my boat is a 17.5'X48" tank. I'd like to get more but, it gets me where I need to go and I think my boat would be unsafe if it went much faster!

[rambler]

I had all the bolt on upgrades on my 3 cylinder 40 Merc...ie, 60 carbs, boysen reeds and I had a jackplate that i spent many hours setting up so the motor would run as efficiently as possible. It was on a 17'x48" Weldcraft.

Loaded to fish it would run 5800 rpms and 37mph (on GPS)...if I took everything out just to go run around, I could get 40 - once I got 41 with a favorable wind and light chop.

After I heard my buddy go on and on about how his would do 45 loaded to fish I boarded with my handheld GPS and broke his heart...he was doing 36.5...he swore that I needed to get my GPS fixed!

I guess my point is that 36/37 mph loaded to fish is pretty fast for a comfortable jon boat. I mean, a tin can with one of these super hopped up 40s will get you a few mph faster, but a couple of mph versus a reliable, biggger and more comfortable ride just wasn't worth it to me.