# 1969 Johnson 4hp outboard seems slow



## V Dog (Apr 6, 2014)

I've been piecing together a little fishing outfit off Craigslist. I now have a Lowe 1232 and a 4hp 1969 Johnson 2 stroke outboard. I've seen plenty of YouTube videos with this combo that has the boat up on plane and running about 15mph with a similar load in the boat. I'm a pretty big guy and have a trolling motor and battery up front which puts my load load at about 300lbs, but I thought I would at least be able to hit 10mph and get it on plane.

The best I could manage today was 6mph. I tried all 4 positions on the manual trim as well as moving the battery forward and backward to play with the weight distribution. 

So when it was running today, it seemed to run fine but had no power. It didn't seem like it revved very high at full throttle like my 2 stroke dirt bike did. But it did seem like it was a linear progression in response to the throttle.

When I got it home, I pulled the engine cover. Everything looks fine and in good condition. I pulled the spark plugs and they looked brownish-gray with no carbon buildup.

The engine is model # 4W69B. I also bought a new 3 gal tank and new fuel line, both from WalMart (3/8" line with bulb). When I bought it, the guy had it in a tank and demonstrated it. It smoked a bit because he had some SeaFoam in his fuel. It seemed to run fine. It's a clean looking engine and the guy fixes them up as a hobby.

I had a canoe with a 50 ft lb thrust trolling motor that would hit 5 mph. So something seems wrong! What should I look at first?


----------



## JMichael (Apr 6, 2014)

I had a 12' Sears Gamefisher semi v with a 3.9hp Merc on it. I got about the same results that you're having. 6.2 to 6.4 mph was the max speed regardless of what the load was. And I mean it when I say regardless of load. Whether it was just me and fuel in the boat or 2 people, 2 batteries, TM and all our fishing gear, it would still hit that approx 6 mph max speed. And my little 30 lb thrust TM would almost go as fast. I never found anything to make it go faster except a larger motor.


----------



## V Dog (Apr 6, 2014)

I just see so many YouTube videos with a 1232 Jon up on plane with a 4hp. :?:


----------



## JMichael (Apr 7, 2014)

[url=https://www.tinboats.net/forum/viewtopic.php?p=347725#p347725 said:


> V Dog » Today, 21:09[/url]"]I just see so many YouTube videos with a 1232 Jon up on plane with a 4hp. :?:


Yea, I saw the same thing, but I've never seen a 4hp put a boat on plane in person so I don't know how they did it unless they had a 100lb driver.


----------



## V Dog (Apr 7, 2014)

Would a 5 hp four stroke give me enough of a boost to get up on plane? That's the highest the boat is rated for.


----------



## earl60446 (Apr 7, 2014)

I don't see a 4hp outboard getting a boat on plane and I don't think the 5hp outboard will do much better at all. You might have a chance going downhill, like over a waterfall or thru some class 5 rapids. :LOL2: That whole get there fast stuff is way over rated anyway. Plus you can make fun of the $30K bass boats when you outfish them this way.
Tim


----------



## V Dog (Apr 7, 2014)

Well, I need the speed to get up river. Some of the spots narrow down and flow about 5-6 mph. Looking at an old 7.5 on Wed.


----------



## JMichael (Apr 7, 2014)

The smallest motor to get a boat on plane that I've personally witnessed was an 8 hp on a flat bottom 12' or 14' jon. I'd estimate the driver to be around 160-175 lbs with a small amount of fishing gear on board and no passenger. And to be honest, I was impressed with how fast it got on plane and how fast it ran.


----------



## Kier (Apr 7, 2014)

I have a 1974 4hp weedless and I get about the same. I wonder if the 4hp and 6hp motors are the same except carb kit?


----------



## ccm (Apr 7, 2014)

I have a 2011 Tohatsu 4hp 4stroke. It will plain off my 14ft v hull SeaKing by Arkansas Traveler with 2 deep cycle batteries ( size 24 & 27 ), gear, bow mounted trolling motor, & me at 250 +. But it would only do this if I sat on the second bench. I just got a stingray jr hydrofoil so I will see if that helps. The motor that you have just might not have the power that it used to have. I've seen a 9.5 ( heavy use ) start first pull every time but it only had the power of a 5 or 6. This might very well be the case with your motor. It's probably to much weight at the rear. Try moving forward while underway on a slick calm day. If it plains off then you have to much weight at the stern and your not getting the leverage you need to plain.


----------



## JMichael (Apr 7, 2014)

A modern 4hp 4 stroke has the HP measured at the prop where the older 2 cycle measured the hp at the crankshaft. That plus the age of the older motor is like apples and oranges to compare one to the other.


----------



## Kier (Apr 7, 2014)

How do you tell or check if it is running at full power. Whay can you do to fix it?


----------



## JMichael (Apr 7, 2014)

If it's not starting and running properly, the first thing I would do is give it a good tuneup. After that, I'd get a tach and see if you're running at optimum RPM for your motor.


----------



## ccm (Apr 7, 2014)

[url=https://www.tinboats.net/forum/viewtopic.php?p=347842#p347842 said:


> JMichael » 07 Apr 2014, 17:25[/url]"]A modern 4hp 4 stroke has the HP measured at the prop where the older 2 cycle measured the hp at the crankshaft. That plus the age of the older motor is like apples and oranges to compare one to the other.



Your right; but it still might be a matter of too much weight and not enough leverage, for such small motors to plain a boat it really has to have very little weight to make this possible.


----------



## JMichael (Apr 7, 2014)

[url=https://www.tinboats.net/forum/viewtopic.php?p=347858#p347858 said:


> ccm » 25 minutes ago[/url]"]
> 
> 
> [url=https://www.tinboats.net/forum/viewtopic.php?p=347842#p347842 said:
> ...



I agree, weight vs hp is probably the single biggest factor with hull shape/size following close behind.


----------



## V Dog (Apr 9, 2014)

Thanks for all the replies. I'm looking for a 7.5 hp and I'll report back if/when I find one.

Hopefully Da Fuzz don't pull me over and ticket me for a 7.5 hp on a max rated 5 hp boat. But I can't imagine anyone would care, much less take the time to pull me over and check. Now if I was blazing at 35mph in a 12' Jon... Different story.


----------



## Kier (Apr 9, 2014)

Would a 6hp plane out a 12 foot v?


----------



## lswoody (Apr 11, 2014)

I have a 2006 5hp 4 stroke Nissan on my 14' Jon boat and I get a top speed of 12 mph going up river. You would probably get up to 15 mph with my motor on your boat.


----------



## V Dog (Apr 13, 2014)

I bought a 1954 Johnson Seahorse 10 hp. I tried it last night and got up to 17-18mph on my phone GPS. The boat seems to need at least 12 mph to stay on plane. 

I'd love to have a lighter motor but I don't think I could downsize hp at all. But this will do for the next 3 months, until I deploy to Korea. Once I get back, I can spend money on a better combo. Maybe a Grizzly 1448 with 25 hp outboard.  

Thanks for all the replies!


----------



## Kier (Apr 13, 2014)

My 12foot v bottom is rated for 7.5hp. Is 10hp to much for that boat?


----------

