Zipper’s Popular Muscle 107” Kit for Twin Cam® 96/103” engines boost torque and horsepower north of 120! The Muscle 107 is a top end and cam kit that gets its displacement boost by increasing the cylinder bore size to 3.937”, while retaining the factory 4-3/8” stroke. Your cylinder tops are decked for trueness and new 10.6:1 forged pistons are precision-fit using the latest Sunnen equipment, while your heads receive Zipper’s high-breathing Stage III treatment with CNC porting, new guides, oversize valves and performance springs. Our Red Shift 577 cams are perfectly matched with the heads and piston to provide big torque & HP across the entire RPM range. Red Shift Dual-Piston cam tensioners are included with Pro-Taper pushrods for a stable valve train and EZ-Adjust covers, with all gaskets needed for assembly. Highly recommended option: our 417-498 blueprinted cam chest/oil system upgrade for improved oil delivery, increasing reliability and durability.
This kit is for the aggressive rider that likes to regularly twist the wick and run up front!
This kit uses your factory head and cylinder cores sent in for modification. An exchange may be possible once your cores are cleaned, inspected and qualified for exchange.


Not legal for sale or use in California on any pollution controlled motor vehicle.
Not legal for sale or use on any EPA pollution controlled motor vehicle.

*To ensure you enjoy a premium experience, Please fill out a Build Sheet/Job Order Sheet prior to completing an order on the website.
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Weight 1 lbs
Emissions Compliant

Country of Origin

Engine Type


Fuel / Air


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