"Harley-Davidson" name for reference purposes only. Not affiliated with Harley-Davidson Motor Co.
Sportster 4-1/2” Stroker Flywheels
This is a brand-new quality product made in America by the famous “Truett & Osborn” company for all Harley-Davidson Sportster motors including 1957-71 900 and 1972-85 1000 “ironhead”, and 1986-* 883, 1100 & 1200 “Evo” for street or racing use. This is exactly what you need as the foundation for your high-performance Sportster motor. Photo (right) shows the actual flywheels. Click the picture for a larger version.
Nothing adds torque like stroker flywheels! Gives you the power for high cruising speed, and better acceleration. The new stroke is 4-1/2” (4.500”), or 11/16” (.625”) longer than the original stroke length. This stroke length produces 63.6” (1043cc) with 1957-71 900 and 883 Evo bore, 71.8” (1177cc) with 1972-85 1000cc bore and 86.5” (1417cc) with 1200 Evo bore. With some minor work, these flywheels will also fit 1952-53 K, but is too short for the 1954-56 KH motors. Other stroke lengths are also available, e-mail for details.
This is a very reasonable investment - it’s only a small part of your total motor cost, and does more in one step than anything else - more than hot cams, bigger carburetor, etc., although those parts will work even better on your stroker motor.
This is not a radical, dangerous and short-lived modification, motors have been built using this stroke length (and inferior parts) for 50 years. The motor will not explode, overheat, be diffficult to start, or wear out immediately (the extra piston travel does shorten the time between top end rebuilds slightly, but we’re talking about years, not months).
The flywheel material is far superior to the original factory cast-iron. Every individually crafted flywheel begins as a 80-55-06 ductile (nodular) iron blank, which is then heat-treated to 220-250 BHN. The 80,000 pound tensile strength blanks undergo an exacting 20-step manufacturing process, utilizing both CNC and conventional precision milling and machining. This insures accurate surfaces, legendary reliability, and excellent “truability”, an absolute necessity when setting up high performance motors to blueprint specifications. If properly installed and maintained, they will not wear out, but give many years of trouble-free service.
Ductile cast-iron is the superior material for flywheels, since its surface provides a better “grip” on the crankpin and shaft tapers than a steel forging to prevent slippage. Cast-iron also damps out internal vibrations better than steel.
These flywheels are a direct replacement (except for stroke length) for the original flywheels in all ironhead Sportster motors. They use all std. Sportster lower-end components, including your own rod set, crank-pin, shafts, bearings, etc. No special parts (other than pistons) are required for installation. However, you will need modification to the cylinder drain holes, crankcase reliefs, etc.
You cannot use stock Sportster pistons with stroker flywheels. Stroker pistons are available from Truett & Osborn: (316) 682-4781 in std. & normal oversizes which already have these adjusted dimensions.
This is more complex than a normal rebuild, requiring prior experience and other assembly work. Victory does not supply pistons, modify pistons, or install these parts. Flywheels must be balanced to your components.
Note: 1957-early 1981 motors use a different shaft and crankpin taper than later motors - you must know and specify the year of the motor.
1986-* Evo 883, 1100 & 1200 motors originally used 3-piece flywheels (shafts integral with flywheel half), and must use the older 1981-85 original or aftermarket replacement separate sprocket and pinion shaft and related hardware (not included) with 1981-85 stroker flywheels. All other std. lower-end components, such as your own rod set, bearings, etc. including the commonized 1981-85 1¼” crank-pin (not included) may be re-used. No special parts (other than pistons, and shafts as described) are required for installation. The longer (1957-85) connecting rods are suggested to improve the rod ratio but will require adjustments to all dimensions. Taller cylinders may be useful here.
ICTORY is the original source of side-valve performance since 1971. Click here for a brief bio on the author: .
Price: $399.95 + postage, insurance, handling & customs fees. Payment & shipping instructions: please read carefully, and be sure to read Terms at the bottom of these instructions.
The flywheels will be promptly shipped to your address in a strong box to insure safe delivery direct from the U.S. manufacturer to save you freight. From time to time, some individual flywheel sets are slightly too heavy for a single box and must be shipped in 2 separate boxes. I won't know this until the box is weighed. If it's too heavy, I will request the additional postage.
All payments must be in US dollars, payable to Victory Library. There may (rarely) be a brief delay in shipment depending on production volume, you will be immediately notified if this occurs and offered a choice of waiting, an alternate stroke length, or a full refund.
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1957-81 Iron Sportster (and 1952-56 K & KH)
1981-85 Iron & 1986-* Evo Sportster
All Other Foreign
All Other Foreign
Due to the high fee that PayPal charges me, a service charge is included in this purchase. This is less than it costs me to collect this money, and more convenient than your bank. If this is not convenient, use your local postal or bank money order.
If you prefer, use a postal or bank
money order only (no personal or business checks) and mail to:
13 Irwin Ct.
Lynbrook NY 11563-2511
Please include your e-mail address.
Click here for other Harley-Davidson stroker flywheels
Terms: the product being sold pursuant to the instructions listed above, and safe delivery of same to the buyer, are warranteed only by the manufacturer and the carrier, respectively, and are not warranteed by Victory, Jeffrey Diamond, or any person acting on their behalf. All sales are final unless the product is not as described. Any claim for loss, damage, or defective product must be made against the carrier or the manufacturer, respectively. By purchasing this product you agree to these terms, and to hold Victory, Jeffrey Diamond, or any person acting on their behalf harmless from any claim, direct or indirect, arising from this transaction or any subsequent transaction, and to seek satisfaction solely and exclusively from the manufacturer and/or carrier. If these terms are not acceptable to you, please do not purchase. If you have a question, or require additional explanation of these terms, please e-mail before purchasing.