Triumph cylinder head

I’ve decided to rebuild the Triumph this year, after being working engine-less since the last BHR Cadwell meeting in 2009 I think), when the 680cc motor blew the RH cylinder apart just above the base flange at the end of the start/finish line straight at Cadwell, just as I was going into Coppice. Fortunately, being used to a two stroke, I’m pretty quick on the clutch and I just pulled off.
The 680cc motor is very exciting in the Triumph, as it does make it bend in the middle a bit and that trait is at the heart of more than one story.
Although I’d probably prefer to keep the big motor in it, a change to classes in the BHR racing has meant that the old vintage class (up to 1934) has been joined to the post vintage class (up to 1948). The grids numbers became too low to run them separately. This meant that whilst before you could get two rides in the vintage with the Scott and two in the post vintage with the Triumph, I have only the ‘up to 48’ class and the ‘unlimited up to ’63 class’ that I can ride with either.
I thought since I can do those four with the same bike, it would be nice to have the Triumph running as a 500 to run in a separate class.
I’ve got a 500 iron head that I over-enthusiastically ported when I was about 15 years old and then later (over)skimmed to increase the compression. It’s an example in iron of what not to do if trying to make a bike go faster. I could possibly recover it, but I do actually have an unmolested one and it may be the wisest thing to start again with a bit more care.

Me and Triumph at Beezumph 2009
Me and Triumph at Beezumph 2009

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