Pat if the top comes loose buy a new Mikuni,I think Hatricks in north QLD have the 36VM for 138 bucks.I reckon spiggott rather than flange mount is the go but you will need another manifold,Les at VMX unlimited has those or ebay one.The off the shelf 36 has pretty much what you need as far as internals(as per CZ madness carb specs) I run a bigger main jet though 330 I think.When you've tuned it up it should make a big difference to how your engine runs,you dont want the top coming off your old carb when your giving it some.