Surging is a sign of being lean. Try to richen the regulator.

Lean could also be from an air leak as well.

I don't recommend using fuels with Castor added. This seems to be an old habit to break. When you do this it does a couple things. First it introduces more volume to the mix without adding nitro means you are reducing the nitro content. Less nitro means the engine settings are more difficult to get correct. Next you could be introducing something with the oils, too much oil can be as frustrating as not enough.

I would say in your case richen the regulator. This means turn it CCW a little. Since you say its dripping fuel out the carb it might not be too lean on the reg screw it could be that it has an air leak somewhere and this is making it lean.

Another option is could be trash in the regulator. This would block fuel from getting to the carb, yet keep the regulator from closing properly and hence the dripping.

Cool Power makes a " Pro Pattern" blend of fuel and this is good stuff to put in a YS engine as well. You don't need to add anything to it, just tap the bottle and run it.

Oil content is very different with different oils that could be used. YS puts a recommendation of minimum 20% oil. This is good and will not get you in trouble. Also since they can't know all the fuels around the world and all the guys that are mixing their own. So 20% is a number that is used as the standard. Most companies make a YS 20-20 blend. Depending on the oil that is used the volume needed could be different. Prime example is the CP 30% heli fuel has 23% oil because the oil is a low viscosity oil and is very thin. So you have to use more of it. If you used 23-24% of the regular oil the motor would not run well as it would have too much oil.


I would bet your problem is debris in the regulator or an air leak somewhere.


Troy Newman