410 is fine if you don't have a 415 motor gear and what most kits come with, just use an HD Z-chain, the BMX style, they are pretty tough.
Originally Posted by Cavi Mike
The leaking carb/manifold is a common and well-known issue and it's easily remedied by a simple o-ring placed inside the manifold.
You must be referring to NT carbs not having an O ring as CNS carbs come with one, it is just too darn short to do the job so you need to seal them up at the groove on top.
I have started using this Permatx Ultra Copper High Temp RTV silicone gasket maker, it is gas resistant and remains slightly pliable.
It likes like this when applied on a CNS.
I have a topic here about it, 'Inside the CNS Carb'.
Personally I've never had an air leak issue on an NT carb with no sealing at all, but I can sure see an O ring in there being worth the extra buck.