Originally spotted on Facebook from the Tokyo Hobby Show was this brand new development from O.S. Engines under their high performance ‘O.S. Speed’ brand.

The new B2102 engine boasts a very striking ‘low profile’ cooling head – going against the grain of convention which traditionally feature much taller alu cooling heads to take advantage of air flow to regulate the engine temperature.

O.S. tell us the engine also has a new carburettor which improves fuel mileage; “Ten-minute driving per fuel tank is not privilege of throttle sensitive top drivers any longer but for everybody now.”

“The new low-profile cooling head makes buggy’s centre of gravity much lower (-17 mm), which improves car handling drastically without sacrificing cooling performance.  Car handling at corner is improved a lot.  New experience.”

The engine will be available to the public from December 2016, no less than the carburetor, crankshaft, crankcase, inner head, outer head all newly developed parts.

Continue reading below for a quick analysis of the new head and why the engine is only 5 grams lighter than the B2101 and 7g lighter than the XZ-B Spec II.

NEW MODEL square stroke
intended use 1/8 off road buggy
code number 1A300
JAN code 4531028 02406 9
displacement 3.46cc  (0.211 cu. inch)
bore 16.40 mm (0.646 inch)
stroke 16.40 mm (0.646 inch)
practical rpm range 4,000 – 42,000 rpm
Max power 2.65 PS/34,000 rpm   2.61 HP/34,000 rpm
weight 347 g  (12.25 oz)


The above photo if you enlarge it, shows the completely different make up of the new B2102 cooling head, the mounting screws are much higher up, potentially indicating the bottom 3 ‘fins’ are potentially solid aluminium – given that the engine is only 7g lighter than the 21XZ-B Spec II, that would make sense in order to aid the heat transfer.