clyinder boar dia.

[tech@1]

well I have one of these famos dead force engines 1986 50hp,cylinders are scored bad so I need to boar them, looking on iboat parts they show the standard piston size as 3.312 but messuring my cylinders before boaring shows 3.189 any clue on what the factory spec is?

 

[javsam]

Re: clyinder boar dia.

For a 1986 Force 50 hp the standard bore is 3.189 and the service limit is 3.191. The standard Bore of 3.313 is for a 1989 to 1992 FORCE 50 HP .

 

[Frank Acampora]

Re: clyinder boar dia.

Standard cylinder bore is 3.187. So, due to wear, the bore on your engine is .002 over which in itself is right at the factory tolerance for wear, out of round, or taper. Be certain that the machine shop uses 3.187 as the spec with an overbore of .010, .020, or .030. Whichever is needed. That is, bore and finish hone to 3.197, 3.207, or 3.217. Pistons are sized for correct clearance at these bore diameters.

My Wiseco catalog does NOT show an .010 over piston however other manufacturers may make them. If your engine only needs .010 overbore to clean it up, CHECK FIRST to see if pistons are available, otherwise use .020 or .030.

 

[roscoe]

Re: clyinder boar dia.

If iboats doesn't have the correct size, you can get them here:
http://www.pistons-online.com/marine.asp?make=Force


20, 30, and 40 over are available.

 

[tech@1]

Re: clyinder boar dia.

thanks all