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Honda BF90A Upgrade?

J

JakeM

New member
Hey!

I have a Honda BF90A 2000 outboard engine and pushing my big 18 super wide deep lund it can struggle with a few extra people in the boat. Without getting to into it, can this simply be improved by upping jet sizes on the carburetor or installing 115 carburetors? Were the engines the same? Looking for help on this
 
The 115 and 130 motors are way heavier than the 75/90's, so presumably way different motors. Count me in on the votes for a different prop or buying a bigger motor....
 
Maximum HP rating is a 150. Never weighed the boat by itself but it’s nothing crazy. Just a 2000 1700 fisherman wide deep lund.
 
Going to try the prop. Right now my biggest tackle is figuring out why it doesn’t want to idle nicely at 600rpm. Engine has no issues like shutting off or anything else you hear people going through. Just cranks more than it should even when hot and doesn’t like going down to that slow troll idle range. Thinking it might be time to do plugs considering there still the factory ones
 
My 1986 Whaler is rated for max 150hp, dry weight 1250, outboard 478ish, fuel capacity 63 gallons, probably weighs 2-2,500 lbs when loaded, top speed about 35mph on gps. I wouldn’t want any less hp. , it’s FI, 130hp 1999.

What rpm do you hit at max speed with a light load, flat calm? You should hit 6,000 or so. If so, your prop is ok, if a lot less rpm, you have some other issue.
 
NSDON said:
My 1986 Whaler is rated for max 150hp, dry weight 1250, outboard 478ish, fuel capacity 63 gallons, probably weighs 2-2,500 lbs when loaded, top speed about 35mph on gps. I wouldn’t want any less hp. , it’s FI, 130hp 1999.

What rpm do you hit at max speed with a light load, flat calm? You should hit 6,000 or so. If so, your prop is ok, if a lot less rpm, you have some other issue.
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Boat dry on calm water gets up to around 35mph on full plane with a full tank. Tank is only around 90-100L on my boat. Hits around 5500-6000 rpm I’d say
 
JakeM said:
Boat dry on calm water gets up to around 35mph on full plane with a full tank. Tank is only around 90-100L on my boat. Hits around 5500-6000 rpm I’d say
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Although I never checked GPS. That speed is off the boats sped. Them normally higher or lower than your real speed? I’m away from my boat for the weekend I can try GPS when I get back
 
Boat and gps usually don’t vary a lot, 35 sounds reasonable for your boat with a single person aboard and 5500-6000 likely means you are propped not bad. Look up your year and model of Lund and check the dry weight, JD Power have that info now, as well as the weight for your Honda. You can also find out the minimum hp for your hull, I’m guessing 90hp in on the low end if you rated for 150hp max.

Hard to compare the whaler and Lund hulls without direct experience. Getting on plane with a full load is a lot tougher and load distribution effects it a lot. You can prop your boat for a quicker getting on plane with a big load but that would likely reduce your top speed.

I am no expert in these matters , hopefully someone with more knowledge will chime in.
 
JakeM said:
Going to try the prop. Right now my biggest tackle is figuring out why it doesn’t want to idle nicely at 600rpm. Engine has no issues like shutting off or anything else you hear people going through. Just cranks more than it should even when hot and doesn’t like going down to that slow troll idle range. Thinking it might be time to do plugs considering there still the factory ones
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Getting it to idle nicely at 600 rpm will require a nearly perfect running engine I think....

Talking perfectly set idle air screws, freshly checked/adjusted carb sync (all carbs pulling exactly the same amount of air on idle), and fresh, or reasonably fresh plugs.

Unless you need that 600 for trolling or something, it's not worth the trouble for my purposes. I'll settle for anything below about 900....
 
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