120hp Force Questions

[blackhawkdc]

I'm trying to find a motor for my bass boat. I've found a 1991 Force 120hp outboard that has two scored cylinders. Is this motor worth repairing? Now I'm assuming that it has a cast iron block since I can't find sleeves for it. The guy is asking $350 for it, I'm betting I can wave some green cash in his face and he'll come down quite a bit. Thoughts anyone? I'm guessing lackof oil cause the scored cylinders, so chucking the oil injection set up would be in order and just mixing the oil. as far as rebuilding the power head, nothing I'm afraid of there. I'm an auto mechanic and have build several engines in my life.

thanks!

Seth Petro

 

[Frank Acampora]

Re: 120hp Force Questions

Offer him 200 and then it will be worth repairing.--Assuming the crank is not scored and the rods are OK.

The block is cast aluminum with cast iron cylinder liners cast in. They can either be rebored up to .030 over or if scored deeper than that, they can be replaced at about 200 a pop. With engines this small, it is not necessary to bore all cylinders, only the ones affected. Wiseco makes sleeves, but you need to find a really good shop to bore the cylinders and replace them. And, if you need to replace the sleeves, then the rebuild is getting expensive and maybe not worth it unless you intend to keep the engine for a few years.

Wiseco pistons will cost 125 each complete with rings, wrist pin, and small end bearings. You can get them up to .040 over but the factory does not recommend more than .030. Gasket set will go around 50 bucks.

These engines do not have oil injection and gas/oil mix is 50 to 1.

Typically, scored cylinders are the result of either broken rings or detonation due to lean running which will also melt the piston.

The rebuild is easy compared to other outboards and auto engines but buy a manual--either factory or Clymers. They explain how to set carbs, synchronize timing, and most important--how to align big ends of rods. Mostly hand tools are necessary but a good flywheel puller helps.

 

[Mwp909]

Re: 120hp Force Questions

If you buy it and you cant fix it you can always sell the lower unit on ebay . I see 120 lower units on there for $450 to $500 all the time. Just a thought.

 

[JoeCrow]

Re: 120hp Force Questions

I second that,
Force parts are in demand
you probably have $500 to $700 easily in parts
lower unit
carbs/reeds
CDI
You can easily recoup your $350 even it can't be repaired