- Joined
- Dec 10, 2008
- Messages
- 7,253
I thought I would post this so one of the forum members could see what I did with his head. I installed 3mm oversized intake valves.
The first picture is a new head with one seat cut out and moved toward the edge of the cylinder. The guide hole has been reangled and bored for an 850 guide and the chamber has been relieved around the valve for less shrouding.
While the other side was being cut like the first I put the new seats and the installation tool in the icebox to cool off.
The head was heated to 380 degrees and the raw seats were tapped into place.
Then the head was put back in the mill and the seats were cut to size and the ports are roughed out with a carbide burr.
The a few more hours with a burr and stones and it has a nice finish.
Then the guide hole is honed for .0015 interference fit.
After the guide is pulled into place it is reamed to around .001 smaller than finished size. A carbide reamer is used for the aluminum bronze material.
Next a guide hone is used to take it to final size.
Then a fine diamond brush makes the finish that is preferred for the Black Diamond coated valves.
Now a mandrel is installed in the guide and a cutter is used to re-angle the spring seat so it matches the guide.
Then the same mandrel is used with a cutter to cut 4 angles on the seat.
Then a bit of work was done in the exhaust to clean the bump in the casting on the sides of the guide.
Then the rest of the exhaust port is smoothed and blended.
Now a set of Black Diamond valves is dropped in for a trip to the flowbench.
This head will be used on an 880 cc street bike so maximum flow and velocity at lifts under .400 inch was the target.
The first test shows what happens when the velocity goes too high too early. The turbulence plugs the port and additional valve lift reduces the flow.
After removing another .020 from the short side floor the flow increased up to .400 like it was supposed to. The blue line is the velocity in comparison to the head before I started.
Here is the CFM numbers before and after.
Now after a set of springs it is ready to make some arm stretching torque. Jim
The first picture is a new head with one seat cut out and moved toward the edge of the cylinder. The guide hole has been reangled and bored for an 850 guide and the chamber has been relieved around the valve for less shrouding.
While the other side was being cut like the first I put the new seats and the installation tool in the icebox to cool off.
The head was heated to 380 degrees and the raw seats were tapped into place.
Then the head was put back in the mill and the seats were cut to size and the ports are roughed out with a carbide burr.
The a few more hours with a burr and stones and it has a nice finish.
Then the guide hole is honed for .0015 interference fit.
After the guide is pulled into place it is reamed to around .001 smaller than finished size. A carbide reamer is used for the aluminum bronze material.
Next a guide hone is used to take it to final size.
Then a fine diamond brush makes the finish that is preferred for the Black Diamond coated valves.
Now a mandrel is installed in the guide and a cutter is used to re-angle the spring seat so it matches the guide.
Then the same mandrel is used with a cutter to cut 4 angles on the seat.
Then a bit of work was done in the exhaust to clean the bump in the casting on the sides of the guide.
Then the rest of the exhaust port is smoothed and blended.
Now a set of Black Diamond valves is dropped in for a trip to the flowbench.
This head will be used on an 880 cc street bike so maximum flow and velocity at lifts under .400 inch was the target.
The first test shows what happens when the velocity goes too high too early. The turbulence plugs the port and additional valve lift reduces the flow.
After removing another .020 from the short side floor the flow increased up to .400 like it was supposed to. The blue line is the velocity in comparison to the head before I started.
Here is the CFM numbers before and after.
Now after a set of springs it is ready to make some arm stretching torque. Jim