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124″ Upgrade for 120R Kit

This kit upgrades the fully CNC ported head from Harley-Davidson. The intake comes standard with our 1.800 inlet or, 1.900 inlet on request to enhance flow. The exhaust port is where we placed most of our attention. When sizing down the exhaust port, it becomes much more efficient. Our solution for this issue is to increase the exhaust valve size while leaving the port and cross section in its standard shape and size.  This kit is supplied with 4.125 piston kit boring and utilizing your existing 120R cylinder. We have had great results with either option.

Please NOTE:
At T-Man Performance we pride ourselves on providing our customers with performance kits that are known world-wide as a leader in proven dependability. We strongly suggest our customers research a professional tuner in your area.

NC State Sales Tax will be applied.

$ 2,497.00
Please contact us to order.



124″ Upgrade to 120R Kit

This is the newest kit offered by T-Man Performance. This kit allows you to make your 120R a 124R without any case modifications. We paid special attention to our piston weight so that our customers would not have the expense of having to rebalance their flywheels. We then install oversized intake and exhaust seats. This process allows the intake and exhaust ports to work with our custom made 2.150 intake and 1.700 exhaust valves, with corrected geometry built in. Both intake and exhaust ports are hand finished, then machined with our multi-angled cutters to insure a smooth flow rate. This kit is includes our custom 4.125 piston set, gaskets, and a T-Man cam of your choice to fit your riding style.

This is the perfect upgrade for your 120” R motor.

Click the Kit Details tab for a complete description of parts and labor as well as pricing for options described above. For more details on the best fit for your riding style – call T-Man Performance.

Kit packages require your cylinders and heads be sent to T-Man Performance for work to be completed.
* When not using T-Man Performance pistons the builder is responsible for checking all valve to piston clearances.
** If during the welding process, heads crack then T-Man Performance is not responsible for replacement and up-charges to repair.


Intake Exhaust Chamber Size
Valve Sizes 2.130″ 1.700″ -.003 / 102cc
Valve Spring Installed Height 1.860″ 1.860″ -.020 / 98.5cc
Valve Spring Seat Pressure 185lbs 185lbs
Valve Spring Pressure @.600″ Lift 420lbs 420lbs -.040 / 94.5cc
Valve Spring Travel .770″ .770″
Valve Seal/Top Retainer Clearance .760″ .725″ -.060 / 91cc
Inlet Sizes 1.800″
Compression Release Options Auto (OEM) Manual