TKR1712X – BLOK 21bM .21 Competition Buggy Engine (Not Broken-In)

This engine is not broken-in. To view the broken-in version, click here.

Intended for buggies but also well suited for truggies, the BLOK 21bM engine provides the smooth, linear power band and excellent fuel mileage required at the highest levels of competition. The bottom-end starts out incredibly smooth, then pulls through the mid and high end to give you the extra grunt to hit that short take-off and additional acceleration for the straightaway. Features include a long-stroke piston and sleeve design, DLC coated silicone-filled crankshaft, laser-etched low profile cooling head, blue 6.0 and 6.5mm venturi, plus all components are interchangeable with the popular 21aP. It comes paired with the 21J carburetor which is widely regarded to be the gold standard due to its tunability and consistency over wide-ranging temperatures and humidity.

Detailed Specs

• Displacement: 3.49 cc/ 0.213 cu.in
• Bore: 16.27 mm / 0.641 in
• Stroke: 16.8 mm / 0.661 in
• Output: 2.55 ps / 2.59 hp @33,000 r.p.m
• Practical R.P.M: 4,000~40,000 r.p.m
• Weight: 362 g / 12.77 oz.

• OS 2090

Recommended Glow Plug

• OS P3

Engine Warranty

• Tekno RC guarantees this item to be free of defects in materials and workmanship for up to 90 days from the original purchase date. Before the engine is run or installed, perform a thorough visual inspection and contact our customer support immediately if anything abnormal is noticed. Warranty will be void if the engine shows any sign of use, disassembly or modification(s). Tekno RC reserves the right to repair or replace any defective item. This item is not eligible for our general warranty program.

Not Broken-In

Want to do the break-in yourself? Now you can! This engine is untouched from the factory so you can perform your favorite break-in process.

We recommend idling at least two tanks through the engine with the needles fat while keeping the head temp at 200°F. Then while keeping the throttle below 50% max, run the car in a parking lot or on a flat surface for about five tanks. Then gradually increase the throttle endpoint and lean the engine until you get to about ten tanks. Always finish the break-in process on the track and be careful to not race the engine until the mechanical pinch is almost gone.

Break-in Tips

• Always preheat the engine to 200°F before starting.
• The engine tune should be fat for the majority of the process. This extra fuel is used to increase the lubrication and flush particles out of the engine. Because it’s fat, you will need to constantly monitor the temperature and make sure it is between 200 and 250°F the entire time.
• Stop the engine between each tank of fuel and make sure the piston is at bottom-dead-center. Let the engine cool to ambient temperature before preheating the engine head to 200°F and starting the next tank.
• Be sure to run 3/4 to a full gallon through the engine before racing.