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741 Stroker data / work in progress
(revised 10.29.00, please help fill in the blanks or get in touch if you have corrections!)

I offer this work in progress....gathering this data is making me think about lots of issues for improving Indians - for example, reviewing S&S literature, they state that for bottom end shafts, these are the proven desirable features to strengthen built-up cranks: 6 degree taper, large diameter at point of connection to flywheel, and keys....do Injuns have keys?? dunno, but as I evaluate how to upgrade my 741 while rebuilding / stroking, I'm looking to make it bullet proof..... guyiii@home.com

741 INDIAN STROKER DATA / OPTIONS
Engine Bore Stroke CI Rod 
length		 Rod 
ratio		 Flywheel 
OD		 RPM @ 
3500 ft/min 
piston speed		 CR
30.50/741 2.500 3.0625 30.07 7.283 2.38:1 7.80 6857 5.00:1?
741 37  2.75/70mm 3.0625 36.38 7.238 2.38:1 7.80 6857 6.05:1+
741 overbored  2.875 (bad!) 3.0625 39.76 7.238 2.38:1 7.80 6857 6.61:1+
741 stroker*  2.75 3.3125 39.35 7.402 2.23:1 7.80 6339 6.54:1
741 stroker  2.75 3.500 41.57 7.402 2.11:1 7.99? 6000 6.91:1+
741 stroker  2.75 3.8125 45.28 7.4375 1.95:1 7.80 5508 7.53:1+
741 BIG stroker* 2.72 4.4375 51.32 7.402 1.67:1 - 4732 8.53:1
45 Scout 2.875 3.500 45.44 7.402 2.11:1 7.99 6000 5.00:1?
45 Scout stroker  2.875 3.8125 49.50 7.4375 1.95:1 7.785 5508 5.45:1+
45 Scout stroker 2.875 4.4375 57.6 7.402 1.66:1 - 4732 6.34:1
45 HD 2.750 3.8125 45.3 7.4375 1.95:1 7.785 5508 5.00:1?
900 Sportster 3.00 3.8125 53.9 7.4375 1.95:1 7.785 5508 -
61” Knuckle 3.3125 3.500 60.3 7.4688 2.13:1 8.312 5056 -
1000 Sportster 3.1875 3.8125 60.8 7.4375 1.95:1 7.785 5508 -
74 Chief 3.250 4.4375 73.625 7.402(?) 1.67:1* - 4732 5.00:1?
74 HD OHV 3.3125 4.28125 73.8 7.440 1.74:1 8.500 4905 -
80 Chief 3.250 4.8125 79.85 7.402(?) 1.54:1* - 4364 5.00:1?
80 HD flathead 3.421875 4.2815 78.7 7.906 1.85:1 8.312 4905 Varied I think
74 HD OHV Shovel 3.4375 3.9688 73.7 7.4375 1.87:1 8.500 5291 8.00:1

? = assumed
* 30.50 flywheels crankpin holes offset bored for 1” crankpin.
+ assumes 5.0 : 1 CR for stock engine & “all other things being equal”.
* if rod length OK.
Piston speed used 3500 fpm, absolute max piston speed 5000 fpm.  Not a design limitation.
Note: Sporty rod width supposedly 1.5”, BT 1.75”
HD BT flywheels weigh 34 lbs. stock, T&O = 28 lbs.
Per S&S, 6 degree taper, bigger diam. & keys are best for shafts.

(* Inserted by Moen: 741 with 69mm pistons, stroker plates, Chief flywheels and Sport Scout rods. Stock crankpin & drive shaft, special pinion shaft & housing. Kiwi p/n 39348s & 20B101s).
 
Engine Drive shaft 
OD		 Crankpin 
OD		 Pinion 
OD		 Taper 
Angle		 Wrist pin 
(inches)		 Crank 
width
30.50/741 0.875 0.875 0.812 6.0 deg 0.750 -
45 Scout 0.875 1.000 0.812 6.0 deg 0.750 -
45 HD 0.875 1.000 0.875 - 0.7915 -
900 Sportster '55-'71 1.00 1.250 1.00 6.0 deg + key 0.7915 -
74 Chief 0.875 1.000 0.812 6.0 deg 0.750 -
74 Knuckle 1.00 1.249 1.00 - 0.7915 3.9575??
74 HD '55-'71  1.25 1.249 1.25 6.0 deg + key 0.7915 3.9375
74 HD  '72-'81  1.25 1.249 1.25 8.0 deg 0.7915 3.9375
80 Chief 0.875 1.000 0.812 6.0 deg 0.750 -
 
ENGINE PRIMARY DRIVE SECONDARY DRIVE
30.50”  Indian 3 row 3/8”pitch chain  5/8”pitch x 3/8 wide chain
45”       Indian 3 row 3/8”pitch chain  5/8”pitch x 3/8 wide chain
74”       Indian 4 row 3/8”pitch chain  5/8”pitch x 3/8 wide chain
45”       HD 2 row 3/8”pitch chain  5/8”pitch x 3/8 wide chain
74"       HD 2 row 1/2" pitch 5/8”pitch x 3/8 wide chain