YS Engines 91SRX-Tareq Side Exhaust Helicopter Engine w/Fuel Injection

This is my favorite motor out of the YS line of motors. This motor will pull slightly harder then a OS 105 but some key things to know about this motor are that the manual is wrong about where to set the needles for break in. You need to open both needle valves 3 complete turns from closed for break in. The settings the manual give are not right. The other thing to know with any YS motor is it will not tolerate a lean run as well as a OS 105, the moment this motor goes lean even for a moment it needs to be pulled out and have the head pulled and check the head gasket and piston ring. Piston ring gets shiny and head gasket will have chunks missing possibly leading to blow by. Thats the trade off imo vs the os 105, the 105 will make good power but not as good as a Ys 91 or ys 96 but the os 105 is designed so even a novice can leave it rich and it pulls and if you go lean for a moment it relatively speaking is usually ok but the YS makes more power but you need to know how to tune to get it to pull and it won’t tolerate a lean run.

great engine! makes tons of power and easy to tune! this is the easiest motor to tune in the tareq ys engine family and holds it well. I have 3 of these engines and love them!