Unless you race SERIOUSLY at a very competitive level, there is no reason to get a 2.4hp engine or worry about someone laughing at your pull-rope. to answer your original question, the OS 21RG is an awesome engine capable of bashing and lower-level racing and it can be had with a pullstart for about $140 Combine this with an 086 pipe from Ofna or RB and you have a hard-to-beat combination for about $200 total. No, it does not have 2.4hp (the RG is rated at 1.9hp) but the RG will spank many 2.2hp plus engines because of its excellent driveability and broad powerband. It will eliminate your need for a starter box, and if you need more power than the RG puts out, you are a better driver than I am. Combine this with OS's excellent durability and ease of tuning and you cant go wrong.

If you race, and already drive well enough to place in the a-main, then you may be better served by a more powerful engine like the novarossi, picco, sirio,
OS VZB, 01-BP, etc. but for general use and occasional racing the OS RG is the best way to go.