The power - way more than I can do justice to. It took me a while to find the rev limiter as after my experience years ago with a Husky 510 I didn't want to find out it only had a mechanical self destuct one. More flexible than I expected a high rpm tuned four stroke single to be which makes it very nice to ride at wet meetings.
Cold starting - it's a softy. Follow the drill and it's one kick.
The Hinson slipper clutch. No locking up the back wheel demon braking for hairpins.
The four speed box. Not a problem at short courses (possibly even a benefit as you can do linked turns in one gear) but they are very close together. Gearing for a hill with long straights gives a pretty high first gear but I can still manage 2.2 second 64 ft times. You run out of gears pretty quickly though so rear sprocket changes of one tooth are required for optimal top speed. I'm doing my calculations based on max rpm of 11500 but max power at 10000 but seat of the pants suggests the tuning mods may have given a real rush in the 'mid range' at the expense of top end. Settling on 15/40 or 39 for most places (with 165/65 x 17 rear) which will give high 80s.
Hot starting. Well I suppose warm really. Given the slipper clutch I can't bump it down the hill as I used to with the Husky (with valve lifter) and the Norwest was obviously electric start. It's not too bad if really hot but at hills where you wait at the top for everyone else to do their runs it cools down to a temperature which makes it very fussy. The hot start lever helps a bit but it needs a very good kick to persuade it in to life. Any tips? I'm 65 and getting arthritic so this makes for a hot, bothered and very cross rider (though it keeps the other guys amused). It's become enough of an issue that I just bought a KTM 350SXF with *electric start* for my dotage.
My lad graduated from a YZ125 last season (which he came second in the NHCA 250 championship on) and has been riding our 96 YZ250 at most meetings, but he had a ride on the 450 at the first event. That was held in subzero temperatures (for humans with windchill factored in) though on dry tarmac. He put in far better times than me and pretty respectable for the 500 class but dropped it in the final 'open' run at the end of the day. Still, 10 others also did including several of the top ten championship contenders. He is looking forward to riding it again in a couple of weeks at a longer hill and hopefully in better conditions. The last few events of the season will be ones he can ride two bikes at, so he can pick up 250 points and also give the 450 an outing. If he takes to it I guess we will keep it and go 5 speed as part of next winter's preparation though I dread to think how much the parts bill will be at Yamaha spares prices in the UK. I had to repair both the bikes last month after they were damaged in a motorway crash (my trailer was rammed on the way to an event). Thank goodnes for used and pattern parts available on Ebay.
I used not to like Japanese bikes (my first love is Italian and would you believe I had a modern French road bike) but working on the YZs has generally been a good experience - not the problems with fasteners made of cheese that we brits used to complain about years ago. I've not touched the orange bike with a tool yet so I'm reserving judgment on that.
Edited by 72degrees, July 04, 2013 - 12:14 AM.