need piston clearance 87 force 125

[87force125]

lookin to bore out my 87 force 125 does any know the clearance also tips on connecting rod removal fun fun !

 

[pnwboat]

Re: need piston clearance 87 force 125

Well the manual doesn't say exactly what the piston clearance should be. It does say that the standard bore is 3.313 - 3.3148. The standard piston size measured 90 degrees to the wrist pin is 3.308 - 3.309. Looks like you're looking at about .005 clearance. Trick to removing the pressed in wrist pins....lots of pressure.

TIP: The Wiseco forged pistons use floating wrist pins with wire locks and different wrist pin bearings. Much easier set up to install and remove. Also much better quality than the standard cast pistons.

 

[87force125]

Re: need piston clearance 87 force 125

im actually useing vertex with the floating pins they told me .004 to .0045 the bore right now is 3.318 stock is 3.312 i guess its just wore .002

 

[Frank Acampora]

Re: need piston clearance 87 force 125

You bore to a specific oversize. The piston manufacturer sizes the piston for proper clearance. So for example: 3.3125 + .010 bore to 3.3225 and buy an .010 oversized piston.
Pistons coem .010, .020, .030, and .040 oversized, however, it is not recommended to bore .040 over.

How do you get .002 from 3.318? I get .006. factory tolerance is .002 so yes, you do need to overbore.