And that good price cant possibly have made provision for a missing exup vale, contact the previous owner. Either they provide you with the missing exup valve or cover the cost of you having to fix the bike. They knowingly sold the bike to you with parts missing, what else is missing or broken on this bike..?
Obviosuly buying a new exup valve is pointless - https://www.fowlersparts.co.uk/parts/418...-a/exhaust
Obviosuly buying a new exup valve is pointless - https://www.fowlersparts.co.uk/parts/418...-a/exhaust