TT Main Jets - Most sizes available but the following common Norton SOHC sizes kept in stock: 260/280/310/320/350/370/400/420/450/460/500/520 and 1300/1600 (methanol). Other sizes (including bigger methanol up to 1900) available to order. Email if you need more information or assistance. Note: TT main jets are also the same as those fitted to Amal RN and Amal GP carbs.