Thunder Tiger CORP. -- PRO-21B-R NO.9474


  1. 947422 MB


Item No. 9474
Displacement(c.c. / 3.49 c.c. / .213 
Bore(mm / in.) 16.26 mm / 0.640 in. 
Stroke(mm / in.) 16.8 mm / 0.661 in. 
Practical R.P.M.(R.P.M.) 3,000 ~ 38,000 rpm 
Output(BHP/RPM) 2.25 BHP / 30,000 RPM 
Weight(g/oz) 390 g / 13.76 oz 


1. PRO-28B-R engine x 1 EA
2. Carburetor Assembly x 1 EA
3. Instructional manual x 1 EA
4. TT logo stickerx x 1 EA


Designed to achieve the easiest operation and max performance over & over, the PRO-21B-R delivers an awesome raw power & durability !
The new webbed reinforced compact crankcase is made for added wearing resistance and provides effective heat dispersion for longer runs.

All PRO series engines are manufactured by automated computer-controlled machinery, using the highest quality materials and state-of-the-art CNC manufacturing techniques to deliver a powerplant that looks and performs better. Precision mixture control carburetor makes adjustments simple, the crankshaft is lightened, and balanced to achieve a smoother and more efficient fuel mixture.
The new 21 engine fits in the same mounting as the original .21/.28 engines, with no additional weight - but delivers greater output and higher practical rpm.

Spare Parts List