Thunder Tiger CORP. -- PRO-21M-OB (1.04:1) NO.9568

PRO-21M-OB (1.04:1)

Item No. 9568
Displacement(c.c. / 3.46 c.c. / .211 
Bore(mm / in.) 16.6 mm / 0.654 in. 
Stroke(mm / in.) 16.0 mm / 0.630 in. 
Practical R.P.M.(R.P.M.) 3,000 ~ 38,000 rpm 
Output(BHP/RPM) 2.10 BHP / 30,000 RPM 
Weight(g/oz) 720 g / 25.39 oz 


1. PRO-21MOB engine x 1 EA 2. Carburetor Assembly x 1 EA 3. Allen wrench x 3 EA (2.5mm &2mm &3mm) 4. Instructional manual x 1 EA 5. TT logo sticker x 1 EA


The Thunder Tiger Pro-21M-OB Outboard engine features an innovative design bound to greatly increase the popularity of the 3.5cc Tunnel Hull class.
A race-proven powerplant is mated to a lower unit utilizing the best gear ratio and flex-cable technologies. A special set of precision helical gears transfers all the power from the crankshaft to the flex-cable, resulting in substantially reduced cable wear and maintenance, while the integrated expansion chamber / muffler reduces exhaust noise. The engine mount allow adjustments to both propeller depth and angle.

To top it off, a Prather S215 prop is included.

The PRO-21M-OB (No. 9568) is equipped with 1.04:1 gear ratio


Side exhaust
ABN construction : Aluminum piston with Nickel-plated brass cylinder liner
Hypereutectic machined Al-Si ringed piston
High strength connecting rod with bushings pre-installed
SG crankshaft for clutch system
Water-Cooled Cylinder Head
One-piece crankcase with squared-off cooling fins
Dual ball bearing-supported crankshaft
2 Needle valves carburetor
9mm carb bore
Vertical mounted main needle valve
State-of the-art CNC machined components
Redline R2 glow plug included

Flywheel, Clutch, Coupling, Water-cooled header
Tuned pipe (No. 9723) available.

Spare Parts List