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1984 merc 90hp upgrades

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max23

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"I tried posting this before b

"I tried posting this before but it doesnt seem like it worked. Anyway im sure this has been covered before but I cant find it in search. Im looking for 5 or so more mph out of this engine for barefooting on a 15 foot ski boat. How can I get there, rejet, exhaust, gearing???? I know its been asked about making it a 115 and i guess thats what im looking for. Can it be done?"
 
"Hi Max,
You can re carby and

"Hi Max,
You can re carby and re jet,shave the head 100/thou,maybe lighten the flywheel and open up the exhaust,then go for a mild port job ,since it is an 84 motor ,it will probably need a freshen up,rings,pistons, bearings at a minimium ,now you may just get 5mph top end you may loose little off the bottom.However you now have a motor that will probably need another freshen up say rings at 50 hrs ,and depending how you treat it a rebuild at 100 hrs maximium.assuming your rods,crank etc etc hold on .After all this expense a 2 litre 135hp with a stainless prop would be a lot better for your intended use ."
 
"It was not exactly 90 at the

"It was not exactly 90 at the wheel in those years. (Flywheel rated). Better off not dumping money into it at the age, than. Look for a 4 cylinder 115 or 125. Bang for bucks. It will go right on to your rigging."
 
Unfortunately I guess that is

Unfortunately I guess that is the information I needed. It doesnt sound easy or cheap. I might just have to try and swap boats or look for a deal on a newer merc. Thanks for the information guys Im gonna be posting another question on here unfortunately its a 2001 Johnson ocean pro 150. Which I would also love to swap.
 
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