Can KTM build a significantly lighter 700-800cc twin? Is there a market for it?

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by LukasM, Oct 28, 2012.

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Would you buy a 370 lbs wet, 80-90 HP, 700-800cc twin, priced between 690 and 990?

  1. Tomorrow, bring it on!

  2. Too small, prefer the exisiting 990 and upcoming 1190.

  3. Too big, prefer a single.

  4. Not interested in a KTM.

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  1. LukasM

    LukasM Long timer

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    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?
    #1
  2. Flanny

    Flanny Flanny-it-up!

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    KTM won't build it, but it can still be built...

    :hide

    :lurk

    Interested to hear people's thoughts...

    :lurk :lurk
    #2
  3. crofrog

    crofrog Long timer

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    the 690E has no sub frame, no provision for a luggage rack, not designed for 2 up and single front disc, no nav tower or wind protection.

    All of those thing add weight and all of those things are things the market would want to make it compete with the other 800cc bikes... If you design it as a narrowly focused dirt adventure tourer and except people to travel lightly and are willing to trade ruggedness for weight I think it could be done and use more composite and TI construction it could be done.



    If the 9x0 is so heavy where's the weight savings to be had? Short of a major cost increase to more exotic materials and AL frames
    #3
  4. roundtripping

    roundtripping Adventourist

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    Don't know about feasibility, but I can tell you I'd buy one tomorrow as well.
    #4
  5. Schannulleke

    Schannulleke Been here awhile

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    Agreed with LukasM. We are looking at something right in between te 950SE and the 690.

    Take the 690 as a starting point, give it a modern light 790cc V-twin engine with lets say 90hp. Improve/reinforce the 690 frame where needed (my guess is not much reinforcement will be needed). Single exhaust muffler. Subframe rear tank. Make more bike versions from this platform (however all R-verions):
    - Enduro: small tank, minimalistic instruments
    - Adventure: medium tank, improved instruments, improved passenger comfort, dual front brake discs
    - Rally: large tank, improved instruments
    - Supermoto: small tank, minimalistic instruments
    - Touring: medium tank, improved instruments, improved passenger comfort, dual front brake discs
    - Duke:...
    - RC:...

    Voila, KTM could build 7 motorcycles out of the engineering effort for 1 good lightweight modular platform. Maximized interchangeability of components and differentiation with a minimum varieties of components:
    - 3 types of fuel tank: small, medium, large
    - 2 types of instrument panels
    -...

    Yes this could certainly be done with a significant weight reduction compared to the current corresponding LC8 motorcycles.
    #5
  6. Yellow Pig

    Yellow Pig Allergic to asphalt!

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    I'd be all in for a lighter 750 cc parallel twin offroad worthy adv bike from KTM.

    Bring it on..........
    #6
  7. mousitsas

    mousitsas Long timer

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    Let's start with the SE and see what we can do to make it lighter without reducing comfort.

    1) Loose 10lbs from creative subframe/fuel tank combination?
    2) Loose another 10lbs from simplifying the exhaust with a 2-1
    3) Loose another 10lb from engine weight
    4) Another 5lbs from redesigned frame+swingarm
    5) Add 5lbs for some sort of simple rally fairing ala raiddesigns

    So, (maybe I am gallant with the lbs) it seems that a 185 kgs 700/800 twin is possible, fully fueled and with lower CG than the SE.
    #7
  8. crofrog

    crofrog Long timer

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    Why would you want the extra width of a parrell twin? Although the possibility of simplified exhaust routing is interesting.
    #8
  9. cyborg

    cyborg Potius Sero Quam Numquam

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    I'm IN, for a V-twin! :lurk
    #9
  10. LukasM

    LukasM Long timer

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    That's a good list.

    I would also prefer a semi-dry sump engine to avoid the extra complexities during oil changes and the weight of an external tank etc.

    For braking power I think the stock Brembo caliper with a single 320mm disc should be fine for most people, it will be better than the 950 SE and the F650GS twin with less weight and better clamping power. The limiting factor is the mostly the tire after all, this is why the single disc F650GS outbrakes the twin disc F800GS, both have the same Brembo calipers as 950/990. And if you really want to put on a sticky 19" or 17" tire then just upgrade to a Motomaster caliper and you will have all the braking power you could need, without the extra weight.
    #10
  11. crofrog

    crofrog Long timer

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    If you want a really small light motor with great ground clearance where is the sump going to be? And how much oil is it going to hold? I'd rather not have a 1qt motor like an RFS for a adv bike... Nor would I want to worry about if the motor is running low on oil loosing oil pressure.

    The 320mm disc is allot more likely to be damaged. The rotor is weaker side to side and lower making it more likely to get it by a rock or catch the ground in a crash... With a dual disc setup you also have redundancy in the system in the event you damage one rotor you can covert it to a single disc.

    Not to mention it's not just about brake power, but about thermal efficiency over repeated stops...
    #11
  12. Tee2

    Tee2 I SAID! Woo Hoo!

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    I think you missed one.

    Easy to lower for a short person or a chick bike. How many guys would buy this for their wife? A REAL off road/adventure bike.
    #12
  13. killurtv

    killurtv free range moron

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    I am in!! 800 twin, 150 pounds lighter, adventure ready, 70-80hp.:clap
    #13
  14. crofrog

    crofrog Long timer

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    haha, and suddenly we see why all the bikes brought to the market are such compromises.
    #14
  15. LukasM

    LukasM Long timer

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    Have you actually tried a single disc setup or is this all theoretical?

    I can (and do) live with the additional risk that a 0.4" lower rotor brings, not an issue in real life IME.

    I don't think I have ever read of a single person unbolting their second disc because it was damaged but you are free to carry a spare if you feel that's necessary, it will still weigh less since there is no second caliper.

    With a 21" wheel and a TKC type tire even repeated stops are not going to overheat a single disc. And again, if you want to use it primarily on tarmac - presumable with a stickier tire - then the Motomaster caliper is very simple upgrade. Those hold up even on the race track in the heavier and more powerful 990 as some other inmates have tested.
    #15
  16. crofrog

    crofrog Long timer

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    I rode around the house like that by just swapping banjo bolts and pulling one caliper off.

    On your hard core adventure tourer your not worried about getting it through rock gardens in once piece?

    Long downhills, 2 up with luggage can put allot of heat into the system.

    Calipers have very little to do with heat management. With the exception of the increased fluid capacity. With good brake fluid though you're allot more likely to get pad fade instead of fluid fade.
    #16
  17. LukasM

    LukasM Long timer

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    No, I am not really worried about the additional risk from the disc going .4" lower, I don't think it really makes a difference as I haven't bent one yet. Switching to a 300mm disc is easy if you are.

    You seem to imply that I think this bike will be able to do everything better than a 990, which I do not. Obviously the focus of this lighter and smaller twin would not be to be a good 2-up with lots of luggage tourer. If that's what you want, then you already have the 990 available.

    In practical application, speaking from my own experience and that of most owners of a F650GS twin, the single disc will work fine even with a 300mm disc, on a heavier bike.
    #17
  18. crofrog

    crofrog Long timer

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    Saying it is what I want is not exactly right. I'm saying what it would take to compete with other 800cc ADV tourers from a feature standpoint.

    I think your concept is neat. My guess is it would be hard to get it much less than 400lb unless you make it really minimal more like a ktm 690E instead of a adventure.

    The 640adv was around 350 dry...
    #18
  19. wilmar13

    wilmar13 Long timer

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    Oh bugger off! Seriously, there are already a million lame bikes... A REAL off road bike needs to have real suspension. Buy a f650gs if you are short and need to flat foot it.
    #19
  20. gunnerbuck

    gunnerbuck Island Hopper

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    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...
    #20