420/500/520 Primary 40% Reduction

  • Sale
  • Regular price $625.00

*Gears in stock

All reduction orders come with a free Promotional T-shirt. Please include your shirt size in the notes of your order if you'd like to receive one (S, M, L, XL, 2XL, 3XL). Add an extra T-shirt to your order for an extra $12. Thank you for your patronage. 


This is our 40% billet gear reduction for foot-shift and standard ES machines. We highly recommend running our stiffer stage 1 clutch springs with this reduction.

*Now offering "CUSTOMER CORE" options for a cheaper upfront cost to you. You MUST send us your stock clutch basket assembly upfront after placing your order. We will use your basket for your reduction and it'll ship back out the following business day after we receive your basket when gears are in stock.

*The "RBM CORE" price includes a $125 core charge on the aluminum clutch basket. Please send in your stock basket and include a copy of the original purchase receipt for the $125 core refund.

*Add our "420/500/520 Master Kit" to your order to get everything necessary for a professional headache free install. The master kit is for the do-it-yourselfer and includes ALL the recommended extra parts. Includes stage 1 clutch springs, front output shaft seal, gasket maker and centrifugal clutch puller. The master kit can be found under the 420-520 sections and the "Parts" section of the website. 



*ES models will need an ES module to prevent electronic shift issues. Springs, ES modules and seal kits are located in the 420/500/520 sections and "Parts" section of the site.