I've seen mention of cutting back the piston skirt. It's something that could be done whilst the barrel is off for porting.
I assume that it is to increase transfer port opening duration to increase the amount of charge entering the crankcase or, is it just to enable full opening in the case of a piston skirt being too long?
What are the disadvantages of doing so?
i assume you're talking about your av7?
i just did some porting, matching things, and cutting the piston skirts. still waiting on a new jet and plug and other things, but it blasts off the line right now compared to stock.
"I assume that it is to increase transfer port opening duration to increase the amount of charge entering the crankcase or, is it just to enable full opening in the case of a piston skirt being too long?"
YUP!
Just clean them up to clear @ TDC
Since cutting it will make it close later you are advancing that ports timing a bit. double edge but a nice trade
cutting the skirt just makes the intake port stay open longer(kinda like lowering the intake port) and helps you use a bigger carb but makes it blow back through the carb more at low rpm unless you have reeds
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