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.
Recommended Tuned Pipes: 51006M, 51016, 51020M
- 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 Manifolds: 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)
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
Fuel type: 25% nitro