Speedfight 2 - Exhaust Crank Case Broken

[The Mexican]

Hi all... this is my first post on this website... like to start by saying a big hello!

Now to my question...

I bought a Speedfight 2 Prost a couple of days ago. I have it serviced and generally checked out a couple of days ago. Everything with the bike is fine apart from a few minors things which needed replacing, tightening etc...

The one thing the mechanic warned me of however was that the top mounting of the exhaust was broken off, this apparently connects to the crank case so can't easily be repaired. He said to fix it he'd need to take the engine out, split it in two and weld on a new mount... he said this would cost around £300!. He said it wasn't worth doing at the moment and I may as well continue riding it until it actually breaks off completely!!. apparently this is a common problem with Speedfights. He also said that alternatively I could just out in a new (reconditioned) engine, which would cost around £250.... however he said that may also be likely to have one of the mounts broken off already.

What are other people's experiences of this problem?, how did you fix it?, how much did it cost? and does anyone know a good, cheapish reliable mechanic in the central London area?

Much appreciate and look forward to any replies I get...

Liam