Going from 25 hp to 35 hp

jitterbug127

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Feb 6, 2023
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601
My camera skills arn’t good. Not sure why my audio is like this. All the videos I took are like this.
 

jimmbo

Supreme Mariner
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May 24, 2004
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13,446
Can the Spark jump a 3/8" Gap on both Cylinder?
Have you ever disconnect one of the Plugs and see how the engine runs under Load, then tried it with the other unhooked?
Is there any signs of Oil-Fuel running down from the top of the Block?
Is the Carb opening Fully?
How long have you owned this motor?
What Pitch is the Prop you have on it currently?

you have a 96 25hp. there is very little difference between it and a 35hp, if the 35 is a twin(though I'm pretty sure there was no 35 in 96, just the 30, of course there might be the Problem Child 3cylinder 35 of that era), as they would both have the same displacement and to get the higher HP, the Torque Curve was moved higher up the Rpm range, and HP is actually lower at lower Rpm. We used to have the 25 and 35 on 2 of the same hulls and very little difference
 

jitterbug127

Chief Petty Officer
Joined
Feb 6, 2023
Messages
601
Can the Spark jump a 3/8" Gap on both Cylinder?
Have you ever disconnect one of the Plugs and see how the engine runs under Load, then tried it with the other unhooked?
Is there any signs of Oil-Fuel running down from the top of the Block?
Is the Carb opening Fully?
How long have you owned this motor?
What Pitch is the Prop you have on it currently?

you have a 96 25hp. there is very little difference between it and a 35hp, if the 35 is a twin(though I'm pretty sure there was no 35 in 96, just the 30, of course there might be the Problem Child 3cylinder 35 of that era), as they would both have the same displacement and to get the higher HP, the Torque Curve was moved higher up the Rpm range, and HP is actually lower at lower Rpm. We used to have the 25 and 35 on 2 of the same hulls and very little difference
Spark jumps a good gap. 3/8” yes. Both cylinders
I’ve not disconnected 1 plug like that before.
No signs of oil/fuel
I’ve owned motor 6 months I’d say
Carb opens fully.
I can check prop in daylight
 

saltchuckmatt

Commander
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Jul 19, 2019
Messages
2,639
Whoa, sorry didn't know.

Giving away stuff for free is not allowed? Just so we are clear about this.

Matt
 

jitterbug127

Chief Petty Officer
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Feb 6, 2023
Messages
601
Thanks for informing me of the policy too! I’d never have thought of that as an issue.
 

film495

Petty Officer 1st Class
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Apr 8, 2009
Messages
285
I don't know if it is advisable, but in that situation I've always wondered it trying a small kicker 3-4 hp, would be enough to get up on plane, and then the kicker can just be killed and pulled up. It might be a way to see if a 5hp jump in size will do what you're thinking before buying/selling. course you'd have to find a little motor to try.

I have a 25 hp on a 15 foot skiff, and with 2 or 3 people it will go faster than I would want to go in it, add a 4th person, and it laughs at the idea of planing out completely, motor wont rev up, should mess with different props, but never have.
 

airshot

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Jul 22, 2008
Messages
5,080
I don't know if it is advisable, but in that situation I've always wondered it trying a small kicker 3-4 hp, would be enough to get up on plane, and then the kicker can just be killed and pulled up. It might be a way to see if a 5hp jump in size will do what you're thinking before buying/selling. course you'd have to find a little motor
 

airshot

Vice Admiral
Joined
Jul 22, 2008
Messages
5,080
Adding a small motor won't work, not at all. In fact it would be dangerous trying to tilt it up out of the way. The bigger motor's thrust will overpower the smaller and create a drag. HP increases must be done thru thrust at the prop.
 

film495

Petty Officer 1st Class
Joined
Apr 8, 2009
Messages
285
Adding a small motor won't work, not at all. In fact it would be dangerous trying to tilt it up out of the way. The bigger motor's thrust will overpower the smaller and create a drag. HP increases must be done thru thrust at the prop.
I'll add that to the list of ideas I've had that aren't any good. Lots of ideas, but some of them are stinkers. Curiousity killed the cat kind of thing.
 
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