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1993 force 70hp

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darrinfj1200

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"Purchased a 1993 501zp stingray boat late last fall with a 70hp force. at the time previous owner said motor ran fine with no problems, after dropping the boat in the water this summer i soon realized the motor wasn't running as smooth as it should and there was excessive smoke. after bringing the boat home i pulled the head to find the #2 piston looks like it melted a bit right at the edge of the piston and scoured the cylinder wall. i was going to buy a total rebuild kit and oversize all cylinders and rebuild complete i think i could get away with oversizing 20 over and was going to bring the block into see if 20 would clean it up. how much more could i safely oversize? (if they think i need to go larger) i measured the cylinders and they are stock in relation to the 70hp force service manual all suggestion would be helpful. seems to be alot of people telling me to scrap it and buy a real outboard motor but i would like to save it i think i could rebuild it even cheaper then buying a good used thanks for listening."
 
"Darrin, there is "lots of

"Darrin, there is "lots of meat" in a Force powerhead.

Had one bored out 30 thou over last year for a guy and the machine shop told me they could easily go to 45 over (and could get Wiseco pistons and rings to fit as well right off the shelf).

The guys at the shop will know how much they need to take to fix things up.

I really would consider having all the cylinders cleaned up and do at least the rings on the other cylinders (again, the machinist should advise).

A total rebuild (bore, pistons, rings, bearings, gaskets/seals) for one of these, doing most of the work yourself, normally runs about 700-1000 bucks - but you end up with a "like new" powerhead.

Don't forget to correct the issue that probably toasted the cylinder in the first place - most likely the carb (clogged jet) - if I'm rememberin' correctly, you have an old Tillotson model 111- kinda bulky and leaky but do the job


Merc no longer stocks a complete repair kit (too many parts discontinued to make it viable), but some individual parts (jets) and all the gaskets are still on the market..."
 
"Thank's for the reply I f

"Thank's for the reply I found a company that sells a complete rebuild kit which it includes all pistons, rings, bearings and all gaskets at a very reasonable price. With shipping the kit is around $500 dollars, first I need to get my powerhead apart check with the machinist what would clean up the cylinders purchase the kit so the machinist can match everything accordingly and hope everything works out in the end so i can get some use out of the boat take care."
 
Re: 93 force 70hp

darrinfj1200, I am trying to rebuild a 94 90 hp & can't find a rebuild kit including pistons. where did you find a kit? thanks,jeff
 
Re: 93 force 70hp

Don't go any higher than 10 if you don't have to.Past that and then your into re-jetting the carbs.
Most parts can be found on e-bay.This site or boats.net. J
 
Re: 93 force 70hp

jerry, I'm at a loss. I've cked everysite I know of & nobody has the pistons I need. wiseco is out of stock,boats.net,marineengine,mercury,iboats, & a couple of others i can't remember. they are piston kit # 834797a5,wiseco # is 3151p1. if you have anymore ideas I would greatly appreciate it. thanks alot, jeff
 
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