Bore than Port
#11
#12
Bore than Port
There are four steps in boring a cylinder.
1. Bore cylinder on a boring bar . It is actually a cutting proccess that puts a slightly undersized perfectly round hole that is square to the base of the cylinder .
2. Chamfering the ports . This proccess takes the sharp edge off of the ports to minimize wear on the piston and rings .
3. Finish honing to size . Honing is something you can think of as *micro grinding* . What is used is a postive force hohn . It will cut a perfect circle even if the hole we are working with is out of round (remeber though , we just came off of the boring bar and we are perfectly round already ) . This type of hone is NOT the kind that has three stones and springs on it . The hone process gives the cylinder walls a proper finish and proper clearance . A typical clearance we are looking for from piston skirt to wall is .003" , this is about the thickness of human hair .
4. Bead hohning . Bead hohning removes no wall material but it does further help to enhance the chamfer work done previously .
In my opinion the best time to port is between steps one and two , any bump of a cylinder wall with a cutting tool will be removed during hohning . It does not HAVE to be done at this time but it is what I prefer .
Rick
1. Bore cylinder on a boring bar . It is actually a cutting proccess that puts a slightly undersized perfectly round hole that is square to the base of the cylinder .
2. Chamfering the ports . This proccess takes the sharp edge off of the ports to minimize wear on the piston and rings .
3. Finish honing to size . Honing is something you can think of as *micro grinding* . What is used is a postive force hohn . It will cut a perfect circle even if the hole we are working with is out of round (remeber though , we just came off of the boring bar and we are perfectly round already ) . This type of hone is NOT the kind that has three stones and springs on it . The hone process gives the cylinder walls a proper finish and proper clearance . A typical clearance we are looking for from piston skirt to wall is .003" , this is about the thickness of human hair .
4. Bead hohning . Bead hohning removes no wall material but it does further help to enhance the chamfer work done previously .
In my opinion the best time to port is between steps one and two , any bump of a cylinder wall with a cutting tool will be removed during hohning . It does not HAVE to be done at this time but it is what I prefer .
Rick
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