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piston size please help

jtnkids

New member
I have a 1995 90 force with a standard bore size of 3.375 I had it bored .20 over it is now 3.394 -3.396 between the 3 cyl. What should the piston size be on a standard and a .20 over
I can not fint this info anywhere.....
 
You would order 0.020" O/S pistons.-----------------Those pistons would typically measure 3.390 or so.----------------Now outboard pistons ( even new ) have quite a taper to them and must be measured at the bottom of the skirt !!!-----A standard piston would measure 3.370"
 
my new pistons are 3.386 this is 9000 over the .20 bored cyl, this seems like two much and the wrong pistons. What do you think?
 
Post a picture of EXACTLY where you measured this !!!! ----------------What if anything is stamped / etched on the piston crown ???--------What brand of piston is it ???------------------More than one person has been confused by piston measurement.--------------3.386 is 0.009 under the bore size, you have to be very , very clear in what you mean / are saying.----------Your decimal points are also all over the place ---------------BE CLEAR IN WHAT YOU MEAN -------------.20 bored cylinder means what ????
 
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Ok the pistons are at a machinist now with the block,they say on the box for 40 to 70 hp engines and the piston has a .5mm stampedon it. The machine shop measured from the bottom of the skirt and it was 3.386he then showed me that the bore was 3.396 showing a 0.009 overage. I will getyou the brand...
 
If the piston is measured correctly at the bottom of the skirt then the bore is a little o/s .---------------It means the motor will run , but perhaps with a little bit of piston " slap " , most folks would not be able to hear that !!
 
What is the ring gap now -------?????????????????---------What brand of piston do you have ?????????????--------------No exact information means -----No exact answer !!!!-----------------------Perhaps just throw those pistons away and order say the -------WISECO equivalent !!!!--------------You say you have a 90 HP motor and the boxes say 40 to 70 HP ---what gives here ????
 
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I dont no, the place I bought them from said there all the same pistons, and I will get all the info you seek In a bit have to call the shop who has the block they have the boxes
 
Not trying to be smart!!!
This is probably too late,sorry.Next time Contact Wiseco pistons.Tell them what you have and need to do.They will sell you what you need.Most rebores only need .010 the first time.
Then you take the new piston and block to the shop.
Doing it the way you did is doing it backwards.Good luck.J
 
Just an observation.............

"piston has a .5mm stampedon it."
comes out to 0.0196850393700787" (0.020")


"they say on the box for 40 to 70 hp engines"
Wiseco says same piston on the 90 too.
 
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