420/500/520 Primary 80% Reduction

  • Sale
  • Regular price $725.00
  • 5 available

*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 80% (actual 83%) billet gear reduction for fuel injected foot-shift and standard ES machines. This reduction requires extra case clearance/cutting around the clutch basket. Our stiffer stage 2 clutch springs are necessary with this size reduction. The stock clutch springs do not provide enough clamping force to hold the extra torque produced from the lower input ratio. Pic may not show correct size.

*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 in stock. Email/message us for shipping info.

*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.


*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.