DirtyBike RK 420 Gold Series Primary Belt to Chain Conversion Surron LBX

DirtyBike Industries primary drive system now available with the best sealed 420 chain available. RK 420 GB MXU!

If you ride in dusty, sandy or muddy conditions you may have primary belt slippage which will eventually fail the stock primary belt, possibly leaving you stranded in the middle of nowhere. Don’t let this happen! Install a DirtyBike Industries primary chain drive system. With the world famous RK GB4MXU chain, this is a necessary upgrade for the serious off-road rider and maintains stock gear ratio.

RK GB420MXU Sealed chain is one of the stongest and quietest 420 chains available.

Master link makes for easier installation and the chain can be replaced easily without removing the swing arm.

This kit comes with db DirtyBike Industries exclusive 1mm aluminum alignment shim allowing you to adjust the sprocket alignment for a quieter, longer lasting drive system.

Buyers and Maintenance Guide

Installation Tool

Please verify your bike model and year before purchasing. If you have questions about fitment, contact us at info@elektrischesracing.com or use the chat below — we’re riders, and we’ll help you get the right part.

Most kits are plug-and-play. Installation guides are included in the box and available on our YouTube channel. For complex installations, we recommend watching our installation videos before starting.

Will this fit my bike?
Check the product title and description for compatible models. Contact us if unsure.

How long does shipping take?
Most orders ship within 1-3 business days from Laguna Beach, CA. Free shipping on orders over $200 (Lower 48).

Do you offer financing?
Yes! Shop Pay Installments and Affirm are available at checkout.

What’s your return policy?
We accept returns within 14 days on unused items in original packaging.