Yep...you guessed it! 50$ is a bargain when you consider the amount of life you get out of them, and from what I hear about the 18cvrx...it will rip through them fairly fast, soic fanta the initial cost is worth the overall amount spent on plastic fantastic ones - but they are great for a basic setup.

Firstly you will have to slightly tweek your engine setup to acccount for the diff gear setup (not always the case) and secondly, I am guessing here but I dare say the .18cvrx torque output is not that great as its only an .18 really. Although its power output is very good. Therefore your choice of a single gear ratio - for a single speed setup; of 47 is not very good really as you will sacrifice MAJOR take ability with that engine. so I would go for around 52 - 49. 47 will work well but its not a great gear ratio for offf road use really and you will have slow take offs and the off road scene is not really well suited to slow take offs and long speed - unless you have a big long wide dirt area to bash in.

Well gear ratio is a biggy. Your tyre size effects your speed dramatically and it also effects the engines ability to cope and put out more torque as the engine has to work harder to put the peddle to the metal so to speak. If you are using the standard size, ergo the dirt boze etc, should be OK. But I was not too sure if you are using a 2speed or not...? If you are using a 2 speed then your choice of 47 is ok and will work well as a second gear but perhaps not the best for that motor (?). Your 2 speeds for that engine or ones that are a good start to use (you should experiment with the cheaper plastic ones first and when you have a good combo then get the steel ones) would be with the 52T S/G as your primary 1st gear followed by a 47T S/G as your 2nd gear although you may wish to choose one slightly higher as I am not too sure about the torque output from the .18cvrx.

On mine at the moment I have a 49T S/G primary 1st and 47T S/G secondary gear but my set-up is completely different from your though and I have a diff engine lol. So my engine pumps out more torque and therefore I can lower the gear ratio more as the rpm output will change the gear after tweeking the clutch for 2nd.

But experiment though lol...its fun aswell to see what it will do as I am not too sure myself as I do not have that engine. Hope it helped.