Speaking of finger ports...
I figured they needed more transfer area as well. You can't give them more time because they seem to demand a long blowdown, longer than any other saw I know of. Finger ports are simply one way to increase transfer area. I chose to go a different route on the 7910, and it really worked. Look at the main transfers, those towards the exhaust. Look how much smaller they are than the secondaries. In addition, when case matching the cylinder to the base, the base of the main transfer duct had to be widened towards the exhaust. I simply carried that base widening straight up into the actual transfer port and widened the port .100". This made them more comparable in size to the secondary transfers. Also impacting this decision was the fact that the secondary transfers cannot be widened like we often do. The ring end pin is in the way. I like how it evened up the transfers anyway, rather than making the difference even greater.
I also opened up all four transfer ducts. This goes against conventional thinking. We're usually concerned about transfer velocity and losing too much by adding volume. The saw wasn't where I wanted it to be, so I was willing to take that chance. It worked. Sometimes you have to be willing to roll the dice and risk a cylinder. Fortunately, it paid off that time.
I will be taking the same approach on this 665/8110. Hopefully I'll get similar results. If not, I'll begin moving the exhaust and transfers up just as Carl and Randy have found to work. I appreciate BOTH of their input. Each of us have our own ideas and styles. I think it works best when we consider and weigh in with what others are doing. We will still have our own styles, but can reach improve our own game with the input of others.
I figured they needed more transfer area as well. You can't give them more time because they seem to demand a long blowdown, longer than any other saw I know of. Finger ports are simply one way to increase transfer area. I chose to go a different route on the 7910, and it really worked. Look at the main transfers, those towards the exhaust. Look how much smaller they are than the secondaries. In addition, when case matching the cylinder to the base, the base of the main transfer duct had to be widened towards the exhaust. I simply carried that base widening straight up into the actual transfer port and widened the port .100". This made them more comparable in size to the secondary transfers. Also impacting this decision was the fact that the secondary transfers cannot be widened like we often do. The ring end pin is in the way. I like how it evened up the transfers anyway, rather than making the difference even greater.
I also opened up all four transfer ducts. This goes against conventional thinking. We're usually concerned about transfer velocity and losing too much by adding volume. The saw wasn't where I wanted it to be, so I was willing to take that chance. It worked. Sometimes you have to be willing to roll the dice and risk a cylinder. Fortunately, it paid off that time.
I will be taking the same approach on this 665/8110. Hopefully I'll get similar results. If not, I'll begin moving the exhaust and transfers up just as Carl and Randy have found to work. I appreciate BOTH of their input. Each of us have our own ideas and styles. I think it works best when we consider and weigh in with what others are doing. We will still have our own styles, but can reach improve our own game with the input of others.
