Ultra Bee Primary Chain Drive Racing Kit With 420 RK MXZ Sealed Chain!

For serious off road and moto racers the non-sealed RK MXZ chain kit is the most efficient kit with the least amount of parasitic drag.

• More Efficient Than Belt
• Better Acceleration
• Longer Run Time
• Easy Maintenance
• Similar To Stock Gear Ratio
• Chain can be replaced without removing the swing arm

Be sure to include the DirtyBike Ultra Bee Swingarm Alignment Tool! Makes the job of aligning the mid shaft shaft and swing arm much easier. 

Note: If you are planning to use this kit with the EMBX XUB-80 motor the front sprocket will require modification. Please contact us for more information. 

Swingarm alignment tool

Buyers and Maintenance Guide

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.