VMX60 and Matcho Mick,thanks for getting back.The OSSA is a 1969 4 speed with a down pipe.The previous owner made his own exhaust and it just looks all wrong.The dimensions for the sections would be great if one of you gents could PM me.The bike will get a full rebuild eventually but first I'd like to get a bit of time on it as I expect it to fall over a few times.(I've NEVER ridden on the dirt,I'm 60 years old)Should be an eye opener for me as I've been plugging away for years on BSA singles.Seeing that you've asked VMX60 I'm in Bendigo.(Will need to get in touch with John O for access to his track).
cheers Lewis