Novarossi KEEP OFF .21-7XL 7-Port .21 Off Road Engine w/Ceramic Rear Bearing (Turbo)

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This is the Novarossi KEEP OFF .21-7XL 7-Port .21 Competition Off Road Engine. The KEEP OFF includes all the tricks and tweaks that Novarossi has developed for their off-road engines, most notably a unique and patented bearing design that reduces the inertia of the rotating mass and increases the engines scavenging, delivering increased throttle response and higher top speed. This, combined with a unique crankshaft, and a patented 7-port sleeve deliver maximum performance. Additionally, the Evolution 2 cooling head was chosen to keep the cooling head mass as low as possible, and the re-designed exhaust gasket helps to increase the life of the gasket.


  • Cooling Head: The 'Lighter & Lower Evolution 2' cooling head has been drilled and milled out to reduce the mass of the cooling head, lowering the Center of Gravity of the engine/car.         
  • Sleeve: The sleeve has 7 transfer ports, and an exhaust with booster ports. The patented port shape and positioning improves the internal fluid dynamics to deliver maximum performance.
  • Crankshaft: The crankshaft has a special shape to reduce turbulence in the crankcase, while the front part was extended to improve the seal and prevent leaking.
  • Gasket: The inner shape of the gasket has been redesigned to allow the use of more material and when combined with an updated material is more resistant to high temperatures.
  • Conrod: The R7 conrod is machined from a super light aluminum that has been checked ultrasonically. The unique shape of the R7 rod creates less turbulence inside the engine.
  • Backplate: The shape of the rear cover helps to optimize the crankcase filling and reduces dead space. The steel plate helps to reduce friction and increases the life of the rod.
  • Carburetor: The carburetor of this engine is made from plastic and in "reverse" style, with a sliding throttle valve. The updated three tuning needles gives a better idle and improves the ability of the engine to return to low rpm after throttling.
  • Rear Ball Bearing: The ceramic rear ball bearing reduces the inertia of the rotating mass and increases the engine's scavenging ability. The bearing, combined with the re-designed case provide increased throttle response and higher top speeds.
Recommended Tuned Pipes: 51006M, 51016, 51020M
Recommended Manifolds: 41021, 41029, 41030

Recommended Glow Plug:
  • C5TGC: For ambient temperature - 32F/50F (0C/10C)
  • C6TGC: For ambient temperature - 50F/77F (10C/25C)
  • C7TGC: For ambient temperature - 77F/104F (25C/40C)
Displacement: 3.49 cc
R.P.M. (max power): 36,800 RPM
Practical Range: 6,000-40,000 R.P.M.
Bore x Stroke: 15.88x17.60mm
Sleeve: 7 ports
Rear Ball Bearing: ceramic
Front Ball Bearing: steel
Crankshaft: 14.5mm - turbo 
Carburetor: plastic - 9mm - slide
Glowplug: Turbo (C6TGC)
Exhaust Position: rear
Weight: 370g
Fuel type: 25% nitro

This product was added to our catalog on May 22, 2013.

Brandon Siegel
Tuesday, Jan 7 2014 (about 2 years ago)
Novarossi KEEP OFF .21-7XL 7-Port .21 Off Road Engine w/Ceramic Rear Bearing (Turbo)
Outstanding truggy engine! Recently retired my Bonito XLB to back up duty and installed the Keep Off 21-7 XLS in my Serpent 811T. Better bottom/mid compared to Bonito with a top end that keeps on pulling strong. Using 9901SS pipe, 41021 header and C6TGC plug on 30% VP/PM fuel.
Jim Niemer
Thursday, May 22 2014 (about 2 years ago)
Novarossi KEEP OFF .21-7XL 7-Port .21 Off Road Engine w/Ceramic Rear Bearing (Turbo)
Its the same engine as a bonito with a different main bearing, do not like the mid range spraybar, was way off at factory settings, I recommend to use a two needle carb, I put one on and the engine ran fine, the transition from low to high was much better with a standard carb. The engine is nothing spectacular but it does run very well.