Now truth be told, a stock TR1 is a pretty rubbish bike. Firstly it is relatively slow for a 1000cc v-twin and secondly it is pretty unreliable by Japanese bike standards.
The first thing you have to be aware of with a stock TR1 is that they have a really weird headgasket, made from a pressed asbestos ring, which sits neatly in a groove. It wasn't exactly the world's worst idea, but on Mk.1 TR1s (the ones marked with 5A8) there was no separator between the groove for the headgasket and the rubber seal of the camchain tunnel.
|It's a pretty rubbish design|
But you don't necessarily have to go for a later cylinder, there's two alternatives for you to modify the stock cylinder, yet both involve a bit of machine-work. Number one is to have the gap between the headgasket groove and the camchain-seal welded up and then machine it back the correct height. This is the bolts 'n' braces way to do it and exactly what Yamaha offered to upset customers in 1981 and 1982 and made stock for the Mk.2 TR1s (marked 19T). A more simple way is to cut a very thin slot with a 1mm-disc on your angle grinder into the space between the headgasket groove and the seal and then stick in a bit of stainless steel sheetmetal.
|Bit hard to see, but this one doesn't have a groove|