by Storkfoot » Wed Jun 17, 2026 1:25 pm
The GT186 has got me to the Euros in Davos and Adria, and others. With an MB/bgm Clubman and a PHBH30, it pulls from low revs and will cruise at 60 plus with plenty of luggage on board. The GT186 was a joy to ride. I had it many years and miss it now. I never fitted an expansion pipe to mine but I did try a Ron Moss Avanti. I found that pipe better suited to the TS1 I had at the time. The MB/bgm Clubman was better suited to the GT186.
I never had a reed petal fail on mine, perhaps as I didn’t fit a high revving expansion. But do carry spares and Allen keys cut down to so has you can get access to the reed block without dropping the engine.
Spare pistons are pretty cheap and it is cast iron so a seizure wouldn’t necessarily be terminal.
The GT186 has a unique, or at least untypical, exhaust flange design. It stands proud to, I believe, allow better cooling. But, if you crack the exhaust uBend on a kerb for example, the sacrificial part is the exhaust flange and not the uBend. This happened to me in Italy in 2017.
That said, I’d still recommend the cast iron GT186 rather than lashing out in a new casing or using a nicasil lined barrel like a Casa or RT. I have a CST Stage 4 tuned 200 now with the same carb and exhaust. It probably beats the GT186 for top speed but it isn’t as torquey low down in the rev range.