Originally Posted by LukasM
Lot's of discussion about this topic in the 1190 thread already, so in order not to derail it any more I'm starting a new thread.
Many of the "old school" 950/990 owners are claiming that this would be a useless exercise as you would just give up a lot of horsepower for only a couple of lbs of weight loss.
Well, I don't agree.
The weight difference between a 690 and a 990 (non ABS!) is around 140 lbs, with the engines accounting for around 40 lbs of that. Considering the smaller displacement and that manufacturing technologies have improved, a die cast 700-800cc twin engine should be at least 10 lbs lighter than the 990, probably more.
So you've got around 110 lbs difference after the engine, you don't think you can beef up a 690 chassis enough to deal with 80-90 horses and add a fairing and be left over with a significant portion of that? The 450RR rear tank that bolts to the 690 chassis is available already and weighs maybe 1 lb more, and with it's 18 liters of fuel will give you better range than a 990 has.
And don't forget that the 690 already has 48mm forks, 21"/18" wheels with Dirt Star rims, the same brakes as the 950SE and that the 690 rally replicas and even the factory LC4 rally bikes (some sporting a >80HP 730cc engine) run through the desert at up to 200 km/h for two weeks during the Dakar using that same trellis frame and I have never heard of anybody having problems, have you?
I think with some modern and creative engineering a 80-90 HP 700-800cc twin with 360-380lbs (wet no fuel) is a realistic goal, and I'd buy one tomorrow.
What do you guys think?
For sure a lightweight V Twin Adventure bike is needed at this time... All the manufacturers seem to have caught the fat pig syndrome, where they are pushing displacement and weights upwards in the so called Adventure category... Most of these bikes end up being a street bike you can ride on gravel..
Aprillia brought out a very lightweight V-twin in the RX a few years back that was a bit of leading edge... The problem is the engine proved unreliable as they were sucking too much power out of it... Drop the power by 20% and it is likely the reliability of that platform would go up while still providing plenty of punch...
KTM or somebody should get there act together and create a 700-750 cc light Adventure... In Canada our insurance rates double when you step up to the next displacement class, I wonder if that is the same elsewhere?
I do like the single 320mm disk idea as I have ran one on my 640 for years with no issues in fact I have nearly 100,000 miles on the original and it is still going strong... I worried about the bigger disk being more prone to getting bent up for the first little while but it never happened and I have ridden some pretty gnarly stuff...Also when riding 2 up loaded I never experienced any problematic brake fade up front even at times when the rear did fade and more emphasis was put on the front to get the job done ... The later 640s went to double disk and according to specs it added 8 lbs to the overall weight... Shedding 8 lbs is a good start for a new platform...