I know this not a new new engine, but has become more and more popular. Just wanted get some discussion on this engine. Some people I people say itna modified version of the 2102. I am also seeing modified versions coming out.

What do people like about it vs other existing OS engines

This topic?
OS R21 .21 1/8 On-road Motor

Also take a look in the other OS topics to get more info
Can the OS R2104 Modded

OS R2104 engine Thread

Rody VS Racing Engines - Onroad Motors

I know it have been covered in other forums, but if I want to know where to find it directly. Not easy.

What's P/S/R replacement number please

OS SPEED R21 EURO SPEC - WORLD CHAMPION PRODUCTS