Merc 500 (50hp) vs Johnson 85

64osby

Admiral
Joined
Jul 28, 2009
Messages
6,799
I am looking at upgrading to the 1970's.

I have a 1967 Merc 500 50hp on a 1964 17' Crosby fish n ski. We use it for tubing and knee boarding. Boat and motor are in great condition and I have never had an issue with the motor (knock on wood). I know it is slow out of the hole. I am looking to get my kids skiing this summer and am considering a change. I have never skied behind this boat, I know it will pull my kids up ok, they are under 100lbs. I don't think it is up for the task of pulling an adult out of the water quickly. It's been 20 years since I've skied but I know my kids will want me to show them first.:eek: Where's the video cam.

The boat I'm looking at is a 1975 ish Aero Marine Javelin 16' to 17' with a 1975 Johnson 85hp. The boats in good condition, the guy says the motor runs great at high speed but "needs the carbs balanced" for it to idle good. The boat is also open bow which is appealing.

Money aside, I can sell my boat for more than the new purchase.
Aero Glass weighs less than the Crosby
Newer trailer is nicer than my gator
Aero Glass is in good shape great gel coat, new sump pump, new power trim, needs upholstery in the bow and i can do that, new impeller and housing on Johnson

My questions are

Will 35 more HP be a noticable difference when trying to ski, and get out of the hole?

Does the Johnson have a good history related to repairs, or lack of?

I,ve read the sticky on tuning the Johnson carbs and feel I can do it.

I love my Merc and would not want to make a change for the worse

Any input would be great, thanks in advance.

I posted this question on the Merc forum and did not get much response,
 

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jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,174
Re: Merc 500 (50hp) vs Johnson 85

When engines lose compression the first place it shows is at idle, they will not idle any more. Do a compression test on that engine before buying it, if its ok, all within 10 psi and 100psi+ then go ahead.
It should pull your arms off.:D

I bought johnson due to the quality of DIY help available here, get the factory service manual for sure.
www.outboardbooks.com
 

bonzoscott

Senior Chief Petty Officer
Joined
Jul 26, 2008
Messages
745
Re: Merc 500 (50hp) vs Johnson 85

I don't know about the engine problem it may have but I used to have a similar set up. 15ft Bow-rider with a '70 85hp. It would do 36 mph with a slalom skier and three people in the boat. Had to have a 17 pitch prop though.
 

64osby

Admiral
Joined
Jul 28, 2009
Messages
6,799
Re: Merc 500 (50hp) vs Johnson 85

Well I went an took a hard look at the boat. Needless to say it's not coming home, today or ever.

The transom is shot has a 1 1/2" bow in it and the glass is cracked were it turns to horizontal. Needs a lot of other little stuff. If I didn't have so many other projects at this time I might consider. 85 horse Johnson, Gator Galv trailer and the boat. The guy was willing to take $500.00 but it would be a lot of work to get it safe.

The transom moved so much it looked like the motor would fall off at any time.

I'll keep looking.
 
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