Quote:
Originally Posted by Driftwood
If it was a 4 stroke, the "lip" might be there to stop burnt exhaust gas being drawn back into the cylinder. But, being a 2 stroke you could almost run the engine on what comes out of the exhaust as there is a lot of unburnt fuel going staight through the engine and hence the need for an exhaust expansion chamber to reflect it back in. The bottom of the port wont affect the timing, only the size of the hole and therefore the amount of gas flowing through. Has anyone out there matched the bottom of the port with the piston crown at b.d.c.? Noticed any difference in engine performance?
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?EH?
they dont use lips to stop gases going back, they have exhaust valves for that.
id like to see you make a 2 stroke run on its fumes, the fuel is burnt the oil is what comes out of the exhaust.
the top of the exhaust port does effect timing (exhaust port timing) it also effect the scavenging effect of 2 stroke
the expansion chamber/pipe is to scavenge the cyliner to draw more fuel/air in and act as a valve using air pulses.