Hi Michael, I think you are absolutely right about the uneven heating of the rings. This also explains the presence of spots of uneven wear on the cylinder surface above the ports. Especially in large diameter cylinders.
Did you see excessive wear above the exhaust ports? If that section of ring is hotter then it will cause more engine oil to vaporize off of that area when it sweeps over it.
@@MichaelForrestChnl Not only above the exhaust. I see spots of worn pattern on freshly honed cylinders of various engines, also above the bridges between the exhaust and transmission. These are air-cooled engines with a large cylinder bore. Too bad I can't attach a photo here.
I don't take educated guesses. I only rely on the porting calculator that I created. It takes into account the Power Band you want, the top RPM, and it requires the porting sizes because it's the the size as well as the durations of the ports that matter
I love your channel guy. I have a question here i don't know how to act. I have an old trial bike (ossa), which exhaust port is trully flat at the top and here is my question. This bike should have good low end torque cause is an trial bike, if i make a good curvature in the exhaust port, i rise the exhaust to, obviously, and i think this should be good for high rpm power to, isn't it? But maybe worst for low rpm power/torque to. What should i do? Are my thinkings correct?
Yes that is correct. For trials use you should leave it alone but if you want it to have better top end power then raise the middle of the port, making a nice curve.
@@MichaelForrestChnl okai thanks a lot! But i mean, i want a good low and mid torque, but the flat top of the exhaust is not good for reliability as i learn from you, so what should i do? Leaving it flat for not get worst low end (or mid torque to, maybe?) and keeping the bad rings life, or making a curvature to better rings life?
Hi Michael, I think you are absolutely right about the uneven heating of the rings. This also explains the presence of spots of uneven wear on the cylinder surface above the ports. Especially in large diameter cylinders.
Did you see excessive wear above the exhaust ports? If that section of ring is hotter then it will cause more engine oil to vaporize off of that area when it sweeps over it.
@@MichaelForrestChnl Not only above the exhaust. I see spots of worn pattern on freshly honed cylinders of various engines, also above the bridges between the exhaust and transmission. These are air-cooled engines with a large cylinder bore. Too bad I can't attach a photo here.
To download the free Excel spreadsheet go to www.dragonfly75.com/moto/various.html
The area where you said that ring hitting the cylinder port, thats what Gordon jennings said. Good to remove the edges on port
how much deegres should 2 transfer ports be to give decent performance with 185 degrees exhaust port
I don't take educated guesses. I only rely on the porting calculator that I created. It takes into account the Power Band you want, the top RPM, and it requires the porting sizes because it's the the size as well as the durations of the ports that matter
I love your channel guy. I have a question here i don't know how to act. I have an old trial bike (ossa), which exhaust port is trully flat at the top and here is my question. This bike should have good low end torque cause is an trial bike, if i make a good curvature in the exhaust port, i rise the exhaust to, obviously, and i think this should be good for high rpm power to, isn't it? But maybe worst for low rpm power/torque to. What should i do? Are my thinkings correct?
Yes that is correct. For trials use you should leave it alone but if you want it to have better top end power then raise the middle of the port, making a nice curve.
@@MichaelForrestChnl okai thanks a lot! But i mean, i want a good low and mid torque, but the flat top of the exhaust is not good for reliability as i learn from you, so what should i do? Leaving it flat for not get worst low end (or mid torque to, maybe?) and keeping the bad rings life, or making a curvature to better rings life?