It's not a huge difference but noticeable, as the revs rise the midrange pull is harder than on the 620, and it pulls strongly to higher revs after that. I fitted the pumper version of the standard carb (which used to be on Harley or Moto Guzzi) so it instantly squirts petrol on the turn of the throttle, without a digital brain calculating if it is dangerous to do it first of all or not
The vibes can be draining after a couple of hours though, that would be my main reason for changing it, I might have one last go with getting the seat gelled up for more comfort though.
It's the mere 142kg of weight which really makes it something fun to ride.
The fact the oil tank is in the frame and having two oil filters just makes it more interesting to bleed the oil after an oil/filter change
The 690 is on my radar, I would probably only ditch this 640 for a 690, I keep looking at the mk1 2008 model, and just lost out on ebay on one for £2250 in fact, I'll try again on the next one that comes along.
Basically the 690 has significantly more power, torque and a much needed 6th gear, together with a second balancer shaft to smooth it all out, at the expense of not much more weight at all.
A supermoto 690 on sticky tyres beats almost anything on the twisties around here, apart from another supermoto.
It's a class of bike I never thought would suit me, and the 620 was just a mad experiment to to see if it lived up to the description I read about it on a website - "DO NOT BUY THIS MOTORCYCLE " ( https://www.motorcyc...620_duke 97.htm). They were right, it's one of the cheapest entry points into hooliganism there is, I should have left it alone...
Only 2016+ 690s had the 2nd balancer shaft
Looking good !
5 fookin gears not 4.5 eh. Mk1 needs a deep clean and a few jobs, paint fork lowers, sort out fuel lines etc, depending how far I want to take it really. The Xj650, I'll probably just get it running sweet, sort out any mechanical needs, give it a good clean and run as is for now.
