This is the Novarossi KEEP OFF 21-4 4-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 factory tuned crankshaft, and 4-port sleeve deliver the best combination of linear power delivery and minimal fuel consumption possible. 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.
Recommended Tuned Pipes:
- 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 4 transfer ports, the best option to provide linear power with minimal fuel consumption.
- Crankshaft: This engine is "Factory Tuned" and features a modified crankshaft to further improve the power output and driveability.
- 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 plastic carburetor is a "reverse" type with a sliding throttle valve.
- 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.
51006M, 51016, 51020M
41021, 41029, 41030
Recommended Glow Plug:
- C5TGC: For ambient temperature - 32°F/50°F (0°C/10°C)
- C6TGC: For ambient temperature - 50°F/77°F (10°C/25°C)
- C7TGC: For ambient temperature - 77°F/104°F (25°C/40°C)
R.P.M. (max power):
Bore x Stroke:
Rear Ball Bearing:
Front Ball Bearing:
14 mm - turbo - tuned
plastic - 9 mm - reverse
This product was added to our catalog on March 29, 2013