Understanding port work?

T

theguy2024

Member
Where did all you smart folks learn port timings and how can I properly learn all this talk about durations and degree wheels etc. Every video on youtube i’ve found has only discussed basic porting and the ones that did talk about port timings simply sucked at explaining it.

All i’ve learned so far from hours of research is the basic “widen exhaust and intake 1mm, raise exhaust 1mm, lower intake 1mm”. I don’t understand port timings, how to get them and what to do with them somebody help me please!
 
You need to download the two stroke tuners handbook by Gordon Jennings, this book will give you a lot of information. Graham Bell did a lot on two strokes also and I found a lot of useful information in his writings.
 
Starting with the intake all I’ve ever done is make sure the piston skirt clears the port at TDC, the piston blocked part of the port on older engines, on most of the newer engines this has been corrected. Port slowly, remember the amount you remove will double in port open time. It take practice to learn what to do, if you go too high with the exhaust you will hurt bottom end power.
 
If you get the exhaust port too wide the rings will wear the cylinder bore at the ends of the port, I learned that on my own.
 
You need a degree wheel, here’s one of mine.
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theguy2024 said:
Where did all you smart folks learn port timings and how can I properly learn all this talk about durations and degree wheels etc. Every video on youtube i’ve found has only discussed basic porting and the ones that did talk about port timings simply sucked at explaining it.

All i’ve learned so far from hours of research is the basic “widen exhaust and intake 1mm, raise exhaust 1mm, lower intake 1mm”. I don’t understand port timings, how to get them and what to do with them somebody help me please!
Click to expand...
That would work if you had the exact same cylinder and everything as whoever came up with 1mm... The cylinders are all different and inconsistent... Those specific measurements leave out 'on a 2012 grubee gt5 cylinder' with a '38mm long rod crank' for example... You can buy ported cylinders from mz Miami Hi /lo hole piston port and reed... California motorbike has ported cylinders for the wildcat pk80.... Then get a few regular ones and compare the difference... Another thing about porting is there made for high rpm with a specific pipe.. if you're ported to crawl to 70mph may not be desired... Buy the jug the pipe the carb and intake and the bottom end for the effect your looking for...
 

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You need to download the two stroke tuners handbook by Gordon Jennings, this book will give you a lot of information. Graham Bell did a lot on two strokes also and I found a lot of useful information in his writings. So I've heard ;)
 
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