skipper

As you say, 10/35 is the standard. This is also what I always used on the TYR unless it was in the Scottish (road use) when it was "upped" to 11/35. As far as I am concerned stay with what you have!

Is it a recent 230 build? Not wanting to "name names" incase this suggestion is wrong, however, I have heard that some "non-Serco" alloy barrels can "ovalise" due to the position of the pushrod cut-out. Just wondering if it might be this, exacerbated when the engine runs hotter, thus losing compression? Just a wild thought!

At around 2:13 into the clip he's riding the TY80 ...as already said above!!