JX21-B04 Ninja JX21-B04 .21 Nitro Engine

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JX21-B04 Ninja JX21-B04 .21 Nitro Engine

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This is the Ninja JX21-B04 Off-Road Buggy Engine.  The innovative JX21-B04 engine includes a new fuel efficient carburetor with 6.5mm reducer. The new carburetor provides smoother easy to drive power and increased fuel efficiency.  The B04 comes with a tungsten weighted crankshaft with DLC coating.  The lightweight cooling head provides exceptional cooling and stable operating temperatures.



  • Ninja JX21-B04 engine.
  • Easy to tune fuel efficient carburetor.
  • Tungsten weighted crankshaft with DLC coating.
  • P3 turbo glow plug.
  • Aluminum 6.5 reducer.
  • Dust cap set.
  • Exhaust gasket.


Carburetor settings.  The carburetor is preset from the factory to begin the break-in process. Once the break-in process is complete the follow setting are recommended for race tune. We recommend a high quality 25%-30% Nitro fuel such as Flash Point race blend fuel.

  • LSN .15mm in from flush.
  • MSN .50mm in from flush.
  • HSN 1.4mm - 1.5mm in from flush.
  • .50mm idle gap. 


1 Review
  • 5
    great engine

    Posted by Todd Lyons on 25th Sep 2017

    i purchased this last week and had adam do the ebis breakin was on the track as soon as i recieved the engine .A few 5 min runs and some tuning on top end and was good to go .thank you adam engine runs great