1990 force 120 need help please.

victordzhur · Jul 24, 2013

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Hi I have recently bought a boat from my brother in law. It has a force motor. Last time he used was two years ago and then it sat on his yard. So, he moved to Canada and I got a boat. I have tried to crank it up, put mugs on, got battery in, and nothing. I checked spark its there, but when I checked compression it was 120 top 105 second about 20 third and last had virtually no compression. That raised concerns, I read a little and decided to pull head. It came off fairly easy, head bolts weren't super tight like you would expect. ALL cylinders wiggle a little bit but the bottom one looks and wiggles the worst, additionally upon closer inspection there are some minor scratches like when aluminum piston rubs against a sleeve. Ill try to post some pictures. Does any one have any suggestion on what to do next. I wanted to do all work myself. Please help.the motor is 1208F90B

foodfisher · Jul 24, 2013

Re: 1990 force 120 need help please.

From my limited experience and the damaged in your photos, you're looking at a complete rebuild or another engine.

victordzhur · Jul 24, 2013

Re: 1990 force 120 need help please.

Thanks. Anyone have an idea what could have happened to bottom piston, it looks as it was beaten with hammer. Same way looks the head.

procraftguy · Jul 24, 2013

Re: 1990 force 120 need help please.

The piston rings caused the scratches best guess was overheated next lean gas compleat rebuild those 15dollar impellers cause more blown engines then nessasary should be replaced every year with your yearly gear lube change id have the block checked for cracks and boared honed if can be but that looks bad

jerryjerry05 · Jul 25, 2013

Re: 1990 force 120 need help please.

Fortunatly all the parts and pieces can be found.
It's a time consuming job but not that hard.
Looks like a few pistons and a gasket set and a couple of holes bored out.
powerhead kit . com remove the spaces.They're in Tampa.
Where are you? Profile,location? You might be close to someone who can help?

victordzhur · Jul 25, 2013

Re: 1990 force 120 need help please.

Thank you very much everyone. I will pull the block either tonight or tomorrow and start fixing it. Any suggestion on which website I can get parts from as there are few.

jerryjerry05 · Jul 25, 2013

Re: 1990 force 120 need help please.

Gave you one.
Also on e-bay you can get some good deals.
I bought a gasket set $65 complete with a head gasket and a few extras that were doubles.

victordzhur · Jul 25, 2013

Re: 1990 force 120 need help please.

Does anyone know how much of a use I can expect out of properly rebuild motor.

pnwboat · Jul 25, 2013

Re: 1990 force 120 need help please.

The key is proper maintenance after the properly re-built motor is broken in correctly..... and put into service. I've seen some 2-stoke outboards that are over 20 years old without a rebuild. Then again I've seen some that are less than a couple of years old and are completely trashed.

Jiggz · Jul 25, 2013

Re: 1990 force 120 need help please.

PNW is right on the money. A properly maintained 2 cycle will last you almost a half a lifetime. If you actually do all the rebuild you will be surprised that it doesn't actually cost that much and the most important thing is acquiring the knowledge and learning along the way.With Wiseco pistons that engine will rock after a complete rebuild.

victordzhur · Jul 26, 2013

Re: 1990 force 120 need help please.

Thanks guys. Come to think of it, I have no clue how to brake it in. I have no manual, maybe someone have a brief idea how its done. I appreciate everyone of you.

foodfisher · Jul 26, 2013

Re: 1990 force 120 need help please.

You're getting up close and personal with youe engine so an OEM service manual should be high on the parts purchase list. Will more than pay for itself in time and frustration savings.

victordzhur · Jul 26, 2013

Re: 1990 force 120 need help please.

Pulled the block out today, will start tearing it apart tomorrow, Monday goes the engine shop and depending on results hopefully parts order. Thanks everyone who pitched in.

victordzhur · Jul 27, 2013

Re: 1990 force 120 need help please.

Took it apart today. I had ALL pistons missing rings. #4 missing both rings, #3missing one and both 1 and 2 had cracked rings. This is odd cause crankshaft look brand new. I'm gonna hone it Monday and order stuff, hopefully this time next week we go try it out.

victordzhur · Jul 27, 2013

Re: 1990 force 120 need help please.

Should I go for forged pistons at this point or regular. What's the difference between the 2 ? Any educated input is well appreciated. Thank you.

pnwboat · Jul 27, 2013

Re: 1990 force 120 need help please.

Forged or cast pistons is more or less a personal preference. Forged are more durable but cost a little more. They also usually have "floating" wrist pins which may require different wrist pin bearings than the cast pistons. The floating wrist pins do not require a hydraulic press to change pistons like the cast pistons. The cast pistons have "pressed" wrist pins. Most of the folks that I've talked to use the forged pistons. Just remember to use twice the amount of oil in the fuel mixture during the break in period. Also when you install the piston assy. into the cylinders, use generous amounts of 2-stroke oil to coat the pistons, rings and cylinders.

victordzhur · Jul 27, 2013

Re: 1990 force 120 need help please.

Thanks pnw this is very useful.

1990 force 120 need help please.

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