BOURKE CYCLE FORMULA

TABLE II
EXHAUST AND UPPER TRANSFER PORT SIZE RANGE BASED ON STROKE

STROKE	EXHAUST PORT SIZE BASED ON 1 TO 0.2188 RATIO	EXHAUST PORT SIZE BASED ON 1 TO 0.250 RATIO	TRANSFER PORT SIZE BASED ON 1 TO 0.1875 RATIO	TRANSFER PORT SIZE BASED ON 1 TO 0.1875 RATIO
0.250”	0.0547”	0.0625”	0.0469”	0.0500”
0.375”	0.0820”	0.0938”	0.0703”	0.0750”
0.500”	0.1094”	0.1250”	0.0938”	0.1000”
0.625”	0.1367”	0.1563”	0.1172”	0.1250”
0.750”	0.1641”	0.1875”	0.1406”	0.1500”
0.875”	0.1914”	0.2188”	0.1641”	0.1750”
1.000”	0.2188”	0.2500”	0.1875”	0.2000”
1.125”	0.2461”	0.2813”	0.2109”	0.2250”
1.250”	0.2734”	0.3125”	0.2344”	0.2500”
1.375”	0.3008”	0.3438”	0.2578”	0.2750”
1.500”	0.3281”	0.3750”	0.2813”	0.3000”
1.625”	0.3555”	0.4063”	0.3047”	0.3250”
1.750”	0.3828”	0.4375”	0.3281”	0.3500”
1.875”	0.4102”	0.4688”	0.3516”	0.3750”
2.000”	0.4375”	0.5000”	0.3750”	0.4000”
2.125”	0.4648”	0.5313”	0.3984”	0.4250”
2.250”	0.4922”	0.5625”	0.4219”	0.4500”
2.375”	0.5195”	0.5938”	0.4453”	0.4750”
2.500”	0.5469”	0.6250”	0.4688”	0.5000”
2.625”	0.5742”	0.6563”	0.4922”	0.5250”
2.750”	0.6016”	0.6875”	0.5156”	0.5500”
2.875”	0.6289”	0.7188”	0.5391”	0.5750”
3.000”	0.6563”	0.7500”	0.5625”	0.6000”
3.125”	0.6836”	0.7813”	0.5859”	0.6250”
3.250”	0.7109”	0.8125”	0.6094”	0.6500”
3.375”	0.7383”	0.8438”	0.6328”	0.6750”
3.500”	0.7656”	0.8750”	0.6563”	0.7000”
3.625”	0.7930”	0.9063”	0.6797”	0.7250”
3.750”	0.8203”	0.9375”	0.7031”	0.7500”
3.875”	0.8477”	0.9688”	0.7265”	0.7750”
4.000”	0.8750”	1.0000”	0.7500”	0.8000”

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