The manual says OEM pistons have a wear of -.25mm on the piston and the cylinder bore has a limit of +.1mm. I'm trying to figure out if the same wear limits hold true for Wiseco pistons. I'm close to the limit on the bore and trying to decide if I can get by with a hone and new rings or if I'll have to bore it to the next size and get new pistons and rings.
Other Do Wiseco pistons and OEM pistons have the same wear limits?
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pm Tricky and ask him.
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What size is the bore at now?
How close to the bore is it? 81.5mm? 83mm? 85mm?
Cast OEM , Pro-X and Vertex pistons do run tighter clearances than the Wiseco forged pistons.
When you look at a Wiseco piston box or the ring package, the part # is the size of the bore the ring end gap is sized for, and this will correspond to being the right finished bore size for piston clearance for the piston clearance marked on the box.
Actually this picture on the Wiseco label doesen't list the piston clearance like the new boxes do.
This piston is 85.50mm.
You can see the part # for the rings is 3367KD
The numbers are the finished size of the bore, 3.367 in. for the rings to fit, if you were to measure the piston it would be whatever Wiseco lists it at, let's say it's .0045.
If the bore is sized to 3.367 in., the piston would measure @ 3.3625 in.
This info off the box helps to size bores before buying the piston kit to see where your @ with your cylinder bore.
But always remember when using Wiseco and/or OEM Cast pistons in a modified engine, (not TOTALLY stock) you need to add at least a minimum of (.001) one more thousandths for piston clearance.
Here's another picture of a Wiseco piston box.
http://cgi.ebay.com/ebaymotors/Wise...rcycles_Parts_Accessories&hash=item4cf2dbbf50
http://cgi.ebay.com/ebaymotors/WISE...rcycles_Parts_Accessories&hash=item5640ad235f
How close to the bore is it? 81.5mm? 83mm? 85mm?
Cast OEM , Pro-X and Vertex pistons do run tighter clearances than the Wiseco forged pistons.
When you look at a Wiseco piston box or the ring package, the part # is the size of the bore the ring end gap is sized for, and this will correspond to being the right finished bore size for piston clearance for the piston clearance marked on the box.
Actually this picture on the Wiseco label doesen't list the piston clearance like the new boxes do.
This piston is 85.50mm.
You can see the part # for the rings is 3367KD
The numbers are the finished size of the bore, 3.367 in. for the rings to fit, if you were to measure the piston it would be whatever Wiseco lists it at, let's say it's .0045.
If the bore is sized to 3.367 in., the piston would measure @ 3.3625 in.
This info off the box helps to size bores before buying the piston kit to see where your @ with your cylinder bore.
But always remember when using Wiseco and/or OEM Cast pistons in a modified engine, (not TOTALLY stock) you need to add at least a minimum of (.001) one more thousandths for piston clearance.
Here's another picture of a Wiseco piston box.
http://cgi.ebay.com/ebaymotors/Wise...rcycles_Parts_Accessories&hash=item4cf2dbbf50
http://cgi.ebay.com/ebaymotors/WISE...rcycles_Parts_Accessories&hash=item5640ad235f
Last edited:
Thanks Chuck. The bore is at 85.09mm (3.350") with kawi flat top pistons in the a 61x cylinder with big bore sleeves. That measurement is with the cylinder lightly honed. The 3347TD rings are what I'd need to replace. So the rings are supposed to fit a 3.347" bore. Is the 3.350" bore too big for just a ring change? Do I need to go up to the next bore?
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I wouldn't base the bore size solely off the rings, base it also with the final piston clearance and see how much the piston has worn and/or collapsed.
Ring gap won't kill performance if it's within reason. Excessive piston to wall clearance will...
Ring gap won't kill performance if it's within reason. Excessive piston to wall clearance will...