Monster Big Bore Kits

When bigger isn’t big enough Revolution offers a Monster solution. Monster kits do require case boring, crankshaft services, and CNC porting for proper performance and reliability. Cam shaft recommendations are also available for your Monster build as well. We offer a host of other services and products to build the biggest American V-Twins available.

Parts are included in big bore kit price. Additional services are required.

The cases must be bored wider to accept the new cylinders, as well as a crankshaft balance to even out the added weight that will be added to the bottom end. Of course, head flow services and larger camshafts are highly recommended to gain the absolute most out of these kits.

Select your year and model from the drop-down lists below. If your vehicle is not listed in our vehicle finder, please contact us at 1-888-779-6885 or info@millennium-tech.net and we will be happy to help find a solution.



Twin Cam 114" Monster Big Bore Kit Silver

Twin Cam 114" Monster Big Bore Kit Silver

114" KITS FOR 99-06 TWIN CAM
4.250" BORE CYLINDERS
10.5:1 FLAT-TOP PISTONS If the Bolt-On Big Bore Kits are appealing, but just aren’t…

$1,125.95

Twin Cam 114" Monster Big Bore Kit Black Highlight

Twin Cam 114" Monster Big Bore Kit Black Highlight

114" KITS FOR 99-06 TWIN CAM
Black Highlight 4.250" BORE CYLINDERS
10.5:1 FLAT-TOP PISTONS If the Bolt-On Big Bore Kits are appealing, but…

$1,125.95

Twin Cam 114" Monster Big Bore Kit Black

Twin Cam 114" Monster Big Bore Kit Black

114" KITS FOR 99-06 TWIN CAM
Black 4.250" BORE CYLINDERS
10.5:1 FLAT-TOP PISTONS If the Bolt-On Big Bore Kits are appealing, but just…

$1,125.95

Twin Cam 124" Monster Big Bore Kit Silver

Twin Cam 124" Monster Big Bore Kit Silver

124" KITS FOR 07-up TWIN CAM AND 99-06 TWIN CAM WITH SCREAMIN' EAGLE STROKER CRANK
Silver 4.250” BORE CYLINDERS; 10.5:1 FLAT-TOP…

$1,125.95

Twin Cam 124" Monster Big Bore Kit Black Highlight

Twin Cam 124" Monster Big Bore Kit Black Highlight

124" KITS FOR 07-up TWIN CAM AND 99-06 TWIN CAM WITH SCREAMIN' EAGLE STROKER CRANK
Black Highlight 4.250" BORE CYLINDERS; 10.5:1…

$1,125.95

Twin Cam 124" Monster Big Bore Kit Black

Twin Cam 124" Monster Big Bore Kit Black

124" KITS FOR 07-up TWIN CAM AND 99-06 TWIN CAM WITH SCREAMIN' EAGLE STROKER CRANK
Black 4.250" BORE CYLINDERS; 10.5:1 FLAT-TOP…

$1,125.95

Twin Cam 131" Monster Big Bore Kit Silver

Twin Cam 131" Monster Big Bore Kit Silver

131" KITS FOR 07-up TWIN CAM AND 99-06 TWIN CAM WITH SCREAMIN' EAGLE STROKER CRANK
Silver 4.250" BORE CYLINDERS; 10.5:1 FLAT-TOP…

$1,125.95

Twin Cam 131" Monster Big Bore Kit Black Highlight

Twin Cam 131" Monster Big Bore Kit Black Highlight

131" KITS FOR 07-up TWIN CAM AND 99-06 TWIN CAM WITH SCREAMIN' EAGLE STROKER CRANK
Black Highlight 4.250" BORE CYLINDERS; 10.5:1…

$1,125.95

Twin Cam 124" Monster Big Bore Kit Granite

Twin Cam 124" Monster Big Bore Kit Granite

124" KITS FOR 07-up TWIN CAM AND 99-06 TWIN CAM WITH SCREAMIN' EAGLE STROKER CRANK
Granite 4.250" BORE CYLINDERS; 10.5:1 FLAT-TOP…

$1,125.95

Twin Cam 107" Monster Big Bore Kit Black Highlight

Twin Cam 107" Monster Big Bore Kit Black Highlight

107" KITS FOR 99-06 TWIN CAM
Black Highlight 4.125" BORE CYLINDERS
10.5:1 FLAT-TOP PISTONS If the Bolt-On Big Bore Kits are appealing, but…

$1,125.95

Twin Cam 107" Monster Big Bore Kit Silver

Twin Cam 107" Monster Big Bore Kit Silver

107" KITS FOR 99-06 TWIN CAM
Silver 4.125" BORE CYLINDERS
10.5:1 FLAT-TOP PISTONS If the Bolt-On Big Bore Kits are appealing, but just…

$1,125.95

Twin Cam 107" Monster Big Bore Kit Black

Twin Cam 107" Monster Big Bore Kit Black

107" KITS FOR 99-06 TWIN CAM
Black 4.125" BORE CYLINDERS
10.5:1 FLAT-TOP PISTONS If the Bolt-On Big Bore Kits are appealing, but just…

$1,125.95

Twin Cam 131" Monster Big Bore Kit All Black

Twin Cam 131" Monster Big Bore Kit All Black

Revolution Performance 131" Big Bore Kit for Harley Davidson 120R engines. Kit comes with 4 1/4 bore, all black…

$1,125.95

Twin Cam 117" Monster Big Bore Kit Silver

Twin Cam 117" Monster Big Bore Kit Silver

117" KITS FOR 07 and Up 5cc dish
Silver 4.125" BORE CYLINDERS
4.375 STROKE; 10.5:1 FLATTOP PISTONS If the Bolt-On Big Bore Kits…

$1,125.95

Twin Cam 117" Monster Big Bore Kit Black Highlight

Twin Cam 117" Monster Big Bore Kit Black Highlight

117" KITS FOR 07 and Up 5cc dish
Black Highlight 4.125" BORE CYLINDERS
4.375 STROKE; 10.5:1 DISH PISTONS If the Bolt-On Big Bore…

$1,125.95

Twin Cam 117" Monster Big Bore Kit Granite

Twin Cam 117" Monster Big Bore Kit Granite

117" KITS FOR 07 and Up 5cc dish
Granite 4.125" BORE CYLINDERS
4.375 STROKE; 10.5:1 FLATTOP PISTONS If the Bolt-On Big Bore Kits…

$1,125.95

Twin Cam 117" Monster Big Bore Kit Black Highlight Dome

Twin Cam 117" Monster Big Bore Kit Black Highlight Dome

117" Kits for 07 & Up, Black Highlight 4.125 Bore- 1cc Dome Piston If the Bolt-On Big Bore Kits are appealing,…

$1,125.95

Twin Cam 117" Monster Big Bore Kit Granite Dome

Twin Cam 117" Monster Big Bore Kit Granite Dome

117" Kits for 07 & Up, Granite 4.125 Bore- 1cc Dome Piston If the Bolt-On Big Bore Kits are appealing, but…

$1,125.95

Twin Cam 117" Monster Big Bore Kit Silver Dome

Twin Cam 117" Monster Big Bore Kit Silver Dome

117" Kits for 07 & Up, Silver 4.125 Bore- 1cc Dome Piston If the Bolt-On Big Bore Kits are appealing, but…

$1,125.95

Twin Cam 127" Monster Big Bore Kit Black

Twin Cam 127" Monster Big Bore Kit Black

127" Kits, Black 4.250 Bore x 4.5 Stroke If the Bolt-On Big Bore Kits are appealing, but just aren’t enough to…

$1,125.95

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Please see technical info, charging instructions and installation instructions here.