Force 120hp model 1201A90B, rebuilding

[djkinvest]

Hi, I resently was given a Maxum 21' boat with a 1990 Force 120hp outboard. The motor has a bad piston and needs to be replaced. I have it all torn down and in the machine shop being rebored. I was wondering which brand of piston to use. I would like to use the best so I can get it running and keep it running for some time. I also would like to know what bearings and other parts to use. Any input would be helpful.<br /><br />Thanks<br /><br />Dave

 

[dave in toledo]

Re: Force 120hp model 1201A90B, rebuilding

i rebuilt my 150 force, try powerheadkit.com

 

[ajp888]

Re: Force 120hp model 1201A90B, rebuilding

hi there I too have just got a 120hp. I wonder if you know what the B stands for on your model number I know the 1201 is the size (120) and the 90 is the year but the book says that the B is important for the prop parts any ideas. I have icq if you fancy a chat, 211652169 I also need help in the prop. is yours a vent version or not. good luck with building your engine I can't get any parts AT ALL in fact i phoned a shop today for a exhaust snout and they laughed down the phone when I said I had a FORCE

 

[djkinvest]

Re: Force 120hp model 1201A90B, rebuilding

Originally posted by AJP 888:<br /> hi there I too have just got a 120hp. I wonder if you know what the B stands for on your model number I know the 1201 is the size (120) and the 90 is the year but the book says that the B is important for the prop parts any ideas. I have icq if you fancy a chat, 211652169 I also need help in the prop. is yours a vent version or not. good luck with building your engine I can't get any parts AT ALL in fact i phoned a shop today for a exhaust snout and they laughed down the phone when I said I had a FORCE

 

[djkinvest]

Re: Force 120hp model 1201A90B, rebuilding

I believe the B stands for the second run or something like that. I know the Mercury purchased force in the late 90's and I believe they built these motors or their parent company did. I purchased a service manual and found it very helpful. I would like to know if the brand of piston makes a differents. As for parts their are a lot of places I found online that have replacement parts. I would look there. My local boat shops told me that it is not worth fitting and if they fitted it they would only get it running for 4 or 5 season and cost me more then it's worth. I decided to do it myself.

 

[eurolarva]

Re: Force 120hp model 1201A90B, rebuilding

Here is a link to force 120 HP. This is for a non L Drive motor. Merc parts

 

[outboard tech]

Re: Force 120hp model 1201A90B, rebuilding

The short answer to your question is wiseco pistons. If you use OEM , you're going to have to heat the pistons to get the rods back on--a dangerous procedure if you're not very careful. Your motor-if 1990--is not Mercury built (about '95 and up)and getting the powerhead off and on is very annoying, but doable. The "B" in the model usually refers to one of the 3 gearcase designs they used. Check the poppet relief valve in the exhaust cover assembly--if it's frozen or corroded, you'll overheat a cyl. right after your rebuild, and the overheat buzzer won't go off. Good luck, they're real strong motors when they're right.