How do I get more HP from my Merc 650

[Ricky S.]

I have heard that on some outboards you can use bigger carbs to increase hp.
So I thought if I put bigger carbs on my Merc 650 Keikhaufer I could increase the hp to 80 or 90 hp.
In my last post I was informed that a Merc 80 or even a 90 hp uses the same carbs as my 650.So is there any way to increase the hp on this motor with out boring out the motor? Thanks.

 

[usskydvr]

Re: How do I get more HP from my Merc 650

Short Answer is NO!

 

[asm_]

Re: How do I get more HP from my Merc 650

In the lower part of the each carb, there is a screw for adjusting HP output for each cylinder. It's usually set to low from factory. You can turn it up to get around 90 more HP.

B

 

[latin monkey]

Re: How do I get more HP from my Merc 650

In the lower part of the each carb, there is a screw for adjusting HP output for each cylinder. It's usually set to low from factory. You can turn it up to get around 90 more HP.

B

what screw would that be?

 

[latin monkey]

Re: How do I get more HP from my Merc 650

must be NOS huh?

 

[achris]

Re: How do I get more HP from my Merc 650

In the lower part of the each carb, there is a screw for adjusting HP output for each cylinder. It's usually set to low from factory. You can turn it up to get around 90 more HP.

B

Love it!!!

The easiest way to get 90hp is to sell the 65 and buy a 90....

 

[Wingedwheel]

Re: How do I get more HP from my Merc 650

Thats funny achris, you beat me to the punch line...

 

[Ricky S.]

Re: How do I get more HP from my Merc 650

Very funny!

 

[achris]

Re: How do I get more HP from my Merc 650

I wasn't being funny... I was dead serious.... The only way you're going to 90hp is to buy a 90hp engine.... Think about it... Your 65 is 4 cylinders, the 90 is 6, so do the numbers, add 50% more cylinders and 50% more hp and you get.... 97hp.... So I really don't see how you can expect 90hp from the small 4.... If you're thinking about the current range of 3 cylinder 90hp engines.... Completely different animals... Your 65 is a small displacement cross-flow engine, the 3 pot 90 is a large displacement looper....

Chris........

 

[chum1]

Re: How do I get more HP from my Merc 650

Its a little off subject but if you want high performance two strokes look to the snowmobile line of engines, 150hp on two cylinders and there every bit as light and very advanced, if someone could adapt one of these to the marine line outboards they would be lightyears ahead....I,m sure a huge engineering hurdle..somebody wake up Carl Keikhaefer!

 

[asm_]

Re: How do I get more HP from my Merc 650

what screw would that be?

It's the one that says "turn here for more HP"

 

[MassillonBuckeye]

Re: How do I get more HP from my Merc 650

It's the one that says "turn here for more HP"

Mines on 11.. Is there any way to get to 20?

 

[Sixmark]

Re: How do I get more HP from my Merc 650

And to think that all this time I was trying to fine tune the supercharger on my outboard trying to get the extra horsepower........what a waste of time. I guess it's a good thing we don't have to figure out how to get better traction huh?

 

[Faztbullet]

Re: How do I get more HP from my Merc 650

All joking aside its very hard to get a few extra horses for a inlne engine due to the restrictive intake and reed block design, they can only flow x amount of CFM's and that it. On my lil inline I spent hours with a dremel tool thinning and grinding them to get a little more flow along with exhaust porting mod's, scallop cutting pistons and intake transfer side of block,blending power ports along with tuner lenghts(cut and weld). Did it help ...yes, extra hp?? maybe 10hp, result it pulls harder on top end than it did.

 

[jerryjerry05]

Re: How do I get more HP from my Merc 650

Won't work.No such thing as an adjustment screw for more HP.
Changing carbs gets nothing just uses more gas(if you can make it run).
Not woryh trying.J

 

[Ricky S.]

Re: How do I get more HP from my Merc 650

Sorry Cris that comment was not aimed at you,I was saying very funny to the guys who where telling me to turn the horse power screw on the bottem of the carb.
I have heard of useing bigger carbs to increase hp such as on a 9.9 and a 15 horse the only difference is the carbs.
I have a friend that tells me he can get his 150 to give him 200 hp by changing the carbs so I figured why not,why would this not work on my 650.
Thanks Cris for being serieous about this issue and not trying to be a clown like some people do.
Thanks again...Rick...

 

[Faztbullet]

Re: How do I get more HP from my Merc 650

You friend is incorrect as there is not anything that can add 50 hp to a engine by a simple bolt on unless its a turbo or giggle gas. I guess he could build a 150 "franken" motor where you clean up engine and leave every thing stock add a spacer and stock carbs an make a ton of hp