Any one know- Force motor A, B or C-- rings & pistons?

brianvolt7

Chief Petty Officer
Joined
Jun 7, 2008
Messages
423
1990 force 120

Does anybody know how to identify what motor I have. Model A, B or C. There is a sticker on the top left of the block that reads: 1201X90A
There is a stamp on the block in the lower left that reads: MG38488
The pistons are stamped with a 2

Model A is a different size rings than the B or C this is why I ask the question of A, B or C.

My other questions:
Does the 2 indicate original piston size or has this been gone through and bored out?
What is the size for stock piston rings or rings that will fit these number 2 piston.
What size ball hone do I buy for these calendars?
Is the MG number above the serial number or is there somewhere else I need to look?
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: Any one know- Force motor A, B or C-- rings & pistons?

Do not use a ball or bottle hone. These engines have a "closed" cylinder bottom end and a 3 stone hone is the correct tool to use.

Not sure about A, B, or C, but I believe the 1990 120 was 3.375 standard bore so if you measure at 3.395 you will find out if it is .020 over.
 

PaulO

Petty Officer 1st Class
Joined
Jan 25, 2010
Messages
225
Re: Any one know- Force motor A, B or C-- rings & pistons?

Clymers states 70 - 150 HP:

STD BORE -

1984-1990A = 3.3130-3.3148

1990B-1999 = 3.3750-3.3762

Prior to 1993 the model number identified the horsepower,features,original boat manufacturer, model year and model revision- (Clymers)

The 90A to me suggests you have the smaller diameter. Check with PWNboat
 

brianvolt7

Chief Petty Officer
Joined
Jun 7, 2008
Messages
423
Re: Any one know- Force motor A, B or C-- rings & pistons?

He recommended that I have the block looked at by a shop. Now if I can just break it loose from the bottom half of the motor I can take it in. I have pushed it, hit it and pryed on it with screw drivers.

I am about ready to take a crowbar to it and try to pry it off.

A remanufactured unit is looking pretty darn good right now. But my wife is saying thats not in the budget, $1900 + shipping:(
 
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