30HP 2 stroke Johnson prop ?

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1648grizz

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Was there a standard prop that came with this engine new ? Would a 10x15 work ok on 1648 with light load ?

Thanks Bill
 
Probably work fine if it's just one guy. I have a 16' and run a 10x13 which revs right out if I'm alone which is seldom and will still get on plane with 3 guys and gear.

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Weldorthemagnificent said:
Probably work fine if it's just one guy. I have a 16' and run a 10x13 which revs right out if I'm alone which is seldom and will still get on plane with 3 guys and gear.

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I have a 2005 25HP 2 stroke Johnson ,ordered a 30HP carb and 10x15 prop. I clocked my top speed at 29-30 mph with just me with 10x13 prop, hoping to gain more top end with 30HP carb and 10x15 prop.
 
15" on a 30hp will be at the top limit of what the motor can handle.. if it's a light load you should be ok..
For reference I'm running a 10x11" on a 16ft v bottom with floors, livewell, bow mount and 2 batteries.. with my dog and I, I'm turning 5700rpm and 45km/h

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Pappy said:
Rather see a 13 on it than a 15. Will be a better all around prop for you with varying loads.

Yes will still have the 13 for heavy loads but when alone I want top speed . I met a friend out on the water last week. He just bought a new 1648 with 40HP 4 stroke Merc . His boat was about 2 or 3 mph Quicker then mine, I can't allow that lol
 
Well got new 30HP carb on my 25HP 2005 Johnson part #0439377 big difference in throttle response but did not notice any more top end speed between OEM 10x13 prop that came with the engine and the new Solas 10x15 I just bought. could that be because it's a Solas prop ?
Topped out at 25mph with two people with both props .
 
Im looking into putting a 35hp carb on my 25 evinrude and Im finding there is more to it than just the carb.

For my motor I need to add the correct reed box/intake and possibly the tuner inside the leg.

Your RPMs are limited (6200?/6500?)so once you get it tuned to where you are hitting the limiter you then need to go up one size (2") pitch on the prop.

Do you have a way to monitor RPM?

How deep is your motor sitting?

And last, where did you find the carb?
 
RaisedByWolves said:
Im looking into putting a 35hp carb on my 25 evinrude and Im finding there is more to it than just the carb.

For my motor I need to add the correct reed box/intake and possibly the tuner inside the leg.

Your RPMs are limited (6200?/6500?)so once you get it tuned to where you are hitting the limiter you then need to go up one size (2") pitch on the prop.

Do you have a way to monitor RPM?

How deep is your motor sitting?

And last, where did you find the carb?
[/quote
I have a tach on order , I believe the RPM max for my 2005 25HP is 5500 , My engine plate sits flush with bottom of boat .Bought the carb from Dusky Marine online down in FL $275 ,they had 8 on the shelf. I cross referenced my 25HP to the 30HP same intake and reeds.
 
RaisedByWolves said:
Im looking into putting a 35hp carb on my 25 evinrude and Im finding there is more to it than just the carb.

For my motor I need to add the correct reed box/intake and possibly the tuner inside the leg.

Your RPMs are limited (6200?/6500?)so once you get it tuned to where you are hitting the limiter you then need to go up one size (2") pitch on the prop.

Do you have a way to monitor RPM?

How deep is your motor sitting?

And last, where did you find the carb?
1648grizz said:
I have a tach on order , I believe the RPM max for my 2005 25HP is 5500 , My engine plate sits flush with bottom of boat .Bought the carb from Dusky Marine online down in FL $275 ,they had 8 on the shelf. I cross referenced my 25HP to the 30HP same intake and reeds.

8 on the shelf is good, $275 each? Ooof! :shock:

Is that a 30hp carb or a 35hp?

Ill have to look it up again, but on another forum there is talk about two different ignition power packs, one limiting rpm to 6200 and the other having no limit.

Is there a number on the side of yours?

The 6200 should have that number on the outside of it somewhere so maybe the 5500 does also.

RPM is going to be the key to going faster.
 
RaisedByWolves said:
RaisedByWolves said:
Im looking into putting a 35hp carb on my 25 evinrude and Im finding there is more to it than just the carb.

For my motor I need to add the correct reed box/intake and possibly the tuner inside the leg.

Your RPMs are limited (6200?/6500?)so once you get it tuned to where you are hitting the limiter you then need to go up one size (2") pitch on the prop.

Do you have a way to monitor RPM?

How deep is your motor sitting?

And last, where did you find the carb?
1648grizz said:
I have a tach on order , I believe the RPM max for my 2005 25HP is 5500 , My engine plate sits flush with bottom of boat .Bought the carb from Dusky Marine online down in FL $275 ,they had 8 on the shelf. I cross referenced my 25HP to the 30HP same intake and reeds.

8 on the shelf is good, $275 each? Ooof! :shock:

Is that a 30hp carb or a 35hp?

Ill have to look it up again, but on another forum there is talk about two different ignition power packs, one limiting rpm to 6200 and the other having no limit.

Is there a number on the side of yours?

The 6200 should have that number on the outside of it somewhere so maybe the 5500 does also.

RPM is going to be the key to going faster.
My 25HP is a 2005, the last year for the 25HP 2 stroke Johnson I believe. I definitely got a better hole shot, the bay was choppy so top end could have been better. I'll be out tomorrow in the creek to get a better top speed test with both props. As far as max RPM I'll know tomorrow as I have a tach now.

I read that the RPM range for my engine is between 4500 and 5500 and exceeding 5500 could damage the engine . I also read here on the forum that a 35HP from the 80s is a 30HP of today. I read a post here from (skids) he has a 2001 25HP, put the 30HP carb on only and gained about 5 mph on top end .
If I can get that I'll be pushing 35mph.... will post results tomorrow.... Part # 0439377 is a 30HP carb . I just checked the part # for my power pack, same # as 2005 30HP. Did have a (6100) # next to it, maybe the RPM limit ?
 
Yeah, I was just tinkering on mine and came across that same number, which should indicate that 6100 is the limit on that powerpack.

If you go over to Boatracingfacts.com and look in the tech page you will find the thread Im following regarding mods. You are looking for the 31.8 engine thread as that is how they refer to them due to them being 31.8ci displacement.

Those guys are running 6500-6800rpm at 45mph+ with their racing hulls and without any immediate negative effects.

Following the oem recommendations will certainly give you a longer life for your motor, but what fun is that? :wink:


There is a whole slew of things you can do for a higher top end speed, some of which seem counter intuitive like jacking up the engine (Airing out the prop) and trimming it to get you to those higher numbers.

Between the thread here by Johnny25 and the 31.8 thread at BRF just about everything motor/prop wise is covered.
 
It takes roughly twice the horsepower to go half again as fast so don't expect huge gains. I went from a 25 to a 35 (1983 so powerhead HP) and top speed with a 13 pitch prop is very close. What it does do is come out of the hole like jack the bear and will even get up on plane with 3 big boys and all the camping gear we can pile on. If you want to pick up more jam, look for a Nissan/Tohatsu m40c or a Yamaha/mariner 2cyl 40. Both are light weight for a 40 and good reliable motors.

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I have a 2005 1648 Grizzly with the 15" transom ,max HP rated at 30 for the boat. Can you buy a new 40HP engine with the 15" shaft ?
 
Weldorthemagnificent said:
It takes roughly twice the horsepower to go half again as fast so don't expect huge gains. I went from a 25 to a 35 (1983 so powerhead HP) and top speed with a 13 pitch prop is very close. What it does do is come out of the hole like jack the bear and will even get up on plane with 3 big boys and all the camping gear we can pile on. If you want to pick up more jam, look for a Nissan/Tohatsu m40c or a Yamaha/mariner 2cyl 40. Both are light weight for a 40 and good reliable motors.

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Huge gains aside, you didnt follow through with your swap is you didnt find the right prop for your combo.

A 10.5 x 13 prop turning 5800rpm will give you the same top speed whether is is backed by a 20hp motor or a 70hp motor. Actually the 70hp will be slower due to the added weight. #-o

Prop pitch vs RPM.
 
I felt a 15 pitch wouldn't be ideal for my boat as I am never alone in it. Usually at least one big boy and often two plus gear. When loaded it runs as it should. Now if the coin were flipped and I fished alone often, it would wear a 15

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27mph with the 10x13 and the 10x15. My RPM was 5335 wot with just me in the boat.
When the boat and motor was new in 2005 my little yellow Garmin GPS read 29 to 30 mph.
Maybe the Garmin lied or the engine lost some compression over the years .
But definitely gets up on plane much better with the 30HP carb.
 
Raised the motor up 1" gained 2 mph . 29mph , guess that's all I'm gonna get with a 30hp on a 1648 Grizzly.
 
I have the same setup as you; a 30 HP carb on a 25 HP motor on my 16' Sylvan Sport Troller. I can get 30-31 with a good stainless 13p prop but 28-29 mph with various aluminum ones. I have a 30 HP intake that I need to install and also swap out the throttle cam off of a 35 that we use for parts to see if that makes any difference and then I might be able to pull a 14p or 15p prop.

Right now I'm running into a lean spot at about 3000 RPM which is annoying and I'm hoping one of those two items solves it.

I don't know what the difference is between the 25 and 30/35 cam. I'm assuming the profile might be slightly different, which I'm hoping to find out as soon as I get a spare minute to go over and pull it from the junker.

I also might try a set of CCMS reeds, but I don't want to start modding until I get the motor running correctly stock.
 
Matt193 said:
I have the same setup as you; a 30 HP carb on a 25 HP motor on my 16' Sylvan Sport Troller. I can get 30-31 with a good stainless 13p prop but 28-29 mph with various aluminum ones. I have a 30 HP intake that I need to install and also swap out the throttle cam off of a 35 that we use for parts to see if that makes any difference and then I might be able to pull a 14p or 15p prop.

Right now I'm running into a lean spot at about 3000 RPM which is annoying and I'm hoping one of those two items solves it.

I don't know what the difference is between the 25 and 30/35 cam. I'm assuming the profile might be slightly different, which I'm hoping to find out as soon as I get a spare minute to go over and pull it from the junker.

I also might try a set of CCMS reeds, but I don't want to start modding until I get the motor running correctly stock.
How much top end did you gain with the carb swap ? I didn't check top end before the swap but when boat was new I hit 29 to 30 mph
 

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