Thanks from the UK for the really useful information on this forum. I recently acquired an 04 YZ450F supermoto for riding in speed (strictly tarmac) hill climbs here in the UK (I don't think you have anything like it in the USA). It's way to fast for me at an easy 89 mph through the finish speed trap at a recent event with higher gearing stil posssible. Dyno tested at 60 bhp it is a bit different to my YZ250 stroker. My son, however, will make proper use of it next year when he is 16 all being well. He is set to come second in the NHCA 250 championship this year on the YZ125 i rebuilt for him and supermoto'd last winter. Here's the 450: http://flic.kr/p/bJ1ypV The stuff on 5 speed conversion was particularly useful as with only the 4 speed box gearing has to be super accurate (I have 3 front and 10 rear sprockets for it) and still it rends to run out of gears to soon on the fast courses. I'll be looking in to getting it done. I love thumpers, having hill climbed a 510 Husky and a tuned 600 Gilera Nordwest back when I was young enough to keep them wide open. Thanks again.