They cost about £1 each - I guess that's about a billion yen but they are an adhesive plastic patch about the size of a small match box. You attach them to the engine part and run the bike. They change colour (very distinctively) with tepm and you read off the colour against a chart. They help to give you an idea of running temp differences. The don't last too well on pipes as the adhesive burns and the leave a nasty mess as they slide off but are a real bonus when designing your own pipe for your bike.
I used one on each pipe and 1 on the front of each barrel, one on the rear of each barrel and one on each head. You'd think the engine would be the same temp all over, especially on a paralell twin but ohhh no.
The NSR would be a really interesting bike to accurately monitor engine temp and especially when using the 300cc kit.
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These aren't the droids you're looking for.