More Power for 640 Adventure

Discussion in 'Thumpers' started by Tim, Dec 13, 2003.

  1. Tim

    Tim Long timer

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    I have gone down the SXC exhaust, Sommer airbox cover and rejetting route.

    What should be next on my shopping list?
    Cam?
    Head work?
    660/670/700cc?

    Has anyone done any of these and if so what results?
    #1
  2. SATEX

    SATEX Long timer

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    I wouldn't presume to answer your question, but I would like to see your assessment of the mods you've done so far. If this info is in another thread, maybe you could point the way? TIA
    #2
  3. Drif10

    Drif10 Accredited Jackass

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    950.

















    It'll be cheaper.
    #3
  4. Flanny

    Flanny Flanny-it-up!

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    It really, really depends on what your goal is.

    To be honest, for the dirt, I already find my 640 is too "peaky" (I have a pretty open exhaust and the TM40 carb, but no further mods.)

    By doing only head work (cams, porting etc), you will only be working on flow, and you will as a result move the power band ever upward, and in my view, make the bike even less "tracktable" for off-roading (Supermoto=Aweseome but not off-road). I find it really takes more focus to keep the back hooked-up as it is.

    The only way to properly get balance is with a big bore kit and stroker kit TOGETHER, in combination with the head work. The extra stroke will ensure that power remains down low. BUT now you are into some serious mods, and after speaking with a guy at schneider cycles at lenght, I have ruled it out as a viable thing to do. On the big bore kits, with the 105mm piston for example, they recommend changing the piston every 5000kms...to give you an idea of reliability concerns that creep in. Not to mention fuel consumption, and maintenance intervals, and the fact that your gear-box and clutch need to be spot-on.

    If you are racing.., and need every edge, and are willing to really wrench, then go for it, but for a reliable tourer/adventure bike, in my view, less is probably more...

    If I were you, I would get the TM40 or FCR41 carb, maybe just a very mild porting job. The pumper carb will really improve low end punch and throttle response, and give you just a bit more top end. It will be the best bang for the buck for sure.

    Maybe, I would consider getting the stainless header pipes from Schineder cycles. They again improve flow, but apparently don;t affect low end much in combination with the SXC can.

    With Pipe, Pupmer Carb and air-box taken care of, I would just leave the engine alone.

    The next thing I would spend money on is suspension mods. I have had my fork and shock re-valved and proper springs put in for my weight and riding style, and WOW! what a difference. This $700CDN mod has made me way faster overall then the (probably same) amount I've spend on getting the motor right.

    After that, if things start to get really fast, you will probably want stronger rims (Excel)...I love 'em efter bashing the shit out of my stock rims in rocky terrain.

    Then, if you want to go even faster...I would stop looking at the bike, altogether and just work at becoming a faster rider...(Gym, nutrition, training, courses, MX track etc, etc) Can you honestly say the bike is holding you back...that you have reached it's limit, and now the ONLY way to go faster is to get a better/faster bike?

    I doubt it.

    I know dudes that can kick my ass on old baged out XR600's..In my view, unless you are at the elite level, it is RARELY that bike that determines how fast someone is on the trail/street.

    I guess at some point you just need to reflect on what you need vs. what you think is cool to do. Sure, you could spend $4K on the motor, and if your suspension sucks, you'll never get that power to hook up. You may find yourself actually SLOWER in the real world, and still be strapped with maintenance and all that...but if it turns your cranck just to know you have a hot motor....well that's ok...(I'm like that with a lot of stuff...).

    So, maybe header pipe, but I would just seriously look at getting a pumper carb for a nice, overall performance gain that really works to make the bike better overall. After that...unless you are racing, I would stop there.

    I'll step off the soap box now.
    #4
  5. Ricardo Kuhn

    Ricardo Kuhn a.k.a. Mr Rico Suave

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    Flanny that is some of the BEST Advice I ever saw, practical, Concrete, down to earth and very real

    :bow:bow:bow:bow:bow

    thank you
    #5
  6. Tim

    Tim Long timer

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    Satex, I'm happy with the results, my "seat of the pants" assesment is that torque and maybe power are up.

    Check out http://www.advrider.com/forums/showthread.php?s=&threadid=20590&highlight=jet for more details on jetting and mods. Flanny and Arch are very knowledgable about this.

    Drif 10 I know, I test rode a 950 but I decided that at the moment it's not for me. I prefer the size and weight of the 640.

    Flanny, I guessed that there would be a reason why it's not being done, thanks for the insight. I'll look into the carb and header pipes option. I may also change my gearing as well.

    Thanks :freaky
    #6
  7. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    Flanny, what are the options for carbs, I've been considering a Kehin 41 for a while now. (I saw your post about "eBay" carbs, but neglected to "Archive" it.)

    I agree with what you wrote, but I think KTim might be using his bike more on B-roads were some extra power might be welcome. I'm finding I'm pretty happy with the power of my 02, now that it has the Supermoto exhaust, airbox, and jetting mods. It seemed funny at first, but I run it at really low rpm's offroad, and at fairly high rpms on road, gives me good traction in the dirt, and plenty of power on the pavement, and avoids the agricultural part of the LC4's powerband. :): Like you said, more power would be hard to "hook Up."


    (Below is what I wrote, prior to reading your post.)

    What size are the new 03 valves? IIRC they are 32mm. I'd hit up Somer, and see what they recomend, I'd guess the cam and larger valves, and maybe some clean up on the head. I'd go for a Kehin 41 first, especially if your riding it in rough and/or technical stuff. As the miles rack up it might then make sense to "bore" it, and you would already have the top end and carb to maximize the "bore" job. "Dirt Bike" magazine built up a LC4 SXC for the Bajamex 300, that was run in the 24 hours of Glen Helen, they felt the motor had more then enough power. (Then again they didn't spend any time on A roads.) The only engine mods on their part, were a full pipe and a Kehin 41. I feel mine needs some gearing changes to get the power right where I want it. I had entertained thoughts of getting an 03, with the new "high flow" head and TPS/ignition, it would seem to be the best canidate for hot rodding. Let us know what you figure out. Cheers, Mack
    #7
  8. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    Thought some might find this of interest.

    Dirt Bike Magazines mods to LC4 for 24 Hours of Glen Helen:

    Pro Circuit exhaust $???
    Dirt tricks triple clamps $340
    Kehin 41mm CFR carb kit $399
    GPR stabilizer kit $450
    Baja Designs HID light kit $450
    Fork mods $235
    Shock mods $133
    KTM Hard Equipment handguards $40
    GPR anti-vibe bar ends $70
    Dunlop 772/776 tires $180
    Custom graphics $80

    PS, it's an interesting read, as they usually avoid bikes of this type. Dirt Bike Dec 2003. 6th place finish in the Open/Expert class, 11th overall.
    #8
  9. Drif10

    Drif10 Accredited Jackass

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    Step away from the microphone and no one will get hurt.

    And we know some guys that kick your ass on old bagged out KLR's, don't we?
    :razor











    the fact that they stomp my dick in the dirt has nothing to do with this conversaton..
    #9
  10. Flanny

    Flanny Flanny-it-up!

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    Hey Mack.

    The fCR 41 is for sure the primo carb.

    But mikuni HS40 (AKA TM40) is a good lower priced alternative.

    Current Ebay listing

    Mikuni HS tuning manual

    From what I understand, the FCR is much more precise in it's higher quality construction, allowing more precise tuning. But the TM can be had for about 100 bucks off ebay...and it still really delivers with the basic accelerator pump, and approx 15% increase in flow due to the absence of the butterfly valve.

    I know what you mean about more power on "b" roads...I'm looking for the same thing (also for long highway sections & passing power)...that is what lead me to have real discussions with Schneider...I compared 20K for a 950, or 5K in engine mods on the 640 (to be 660) and thought....hmmmm..I could just hop the 640 up, and I could rip on the highway...but alas..I think the whole reliability/tractability issue would come back on the type of rocky/roller coaster logging roads I ride mostly, and the long extended tours I do...I'm already changing oil about every-other weekend....grrrr.. Last seson I put on just about 11,000 miles...so maintenance intervals are a concern.

    Like I said, it's really very personalized and really depends on the goal...and there is no free lunch, every gain in one place will usually come at the expense of a loss somewhere else....

    FWIW the 2003 valves are 32mm, and can be easilly retrofitted to pre-2003 heads with a simple valve grind...the guides eveything are the same...so if you do have the head off, this is a good one to go for.

    Oh, if only one bike could truly to it alll...I'm thinking a light 600cc v-twin may be the holly grail...good torque, good power, lighter than 950...hmmm....Like a 360lb KTM LC8 660....dream...drream...drool.....
    #10
  11. Flanny

    Flanny Flanny-it-up!

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    Hey...I've held my own against EVERY KLR encounter....just ask Fasteddy...
    :1drink
    #11
  12. Rad

    Rad Done riding

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    Gotta agree

    I did the race can, re-jet, drilled slide and opened the air box. Great power and far less vibes.

    In the dirt I have to be careful 'cause she has far more power than she needs.:arg
    #12
  13. Tim

    Tim Long timer

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    I know what you mean about more power on "b" roads...I'm looking for the same thing (also for long highway sections & passing power)...that is what lead me to have real discussions with Schneider...I compared 20K for a 950, or 5K in engine mods on the 640 (to be 660) and thought....hmmmm..I could just hop the 640 up, and I could rip on the highway...

    Flanny that's exactly the lines that I was thinking along and is why I asked the question.

    Forgive my ignorance but what will a change of carb do for me in "seat of the pants" terms?
    #13
  14. Drif10

    Drif10 Accredited Jackass

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    He says that was only cause you hit his kill switch....
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  15. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    Flanny only hit the kill switch, because he doesn't want anyone to realize he has hardended his own ignition, and mounted the DASDD (digital atomic static discharge device) to disable other competitors. Flanny has a good heart, it's just that he hates to see anyone even risk getting hurt, by trying to ride so fast! :rofl
    #15
  16. Flanny

    Flanny Flanny-it-up!

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    The FCR41 or TM40 will make a VERY noticeable difference in "snap-the-throttle" response, and a nice overall gain in power throughout the range. Wheelies in 1,2 or 3rd gear. I can loft the front end on my bike at 80kph over a rise in the road!!! Yee-haw!

    That's the "seat-of-the-pants" difference...It's no doubt the biggest bang for the buck for sure.
    #16
  17. Tim

    Tim Long timer

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    Thanks Flanny, Guess I'll be back at you when I need help setting up jetting an' stuff!!
    #17
  18. fasteddy

    fasteddy Been here awhile

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    Yup, you held your own all right, your own end of the tow rope hanging from the back of my KLR!! Boy it sure must be nice riding back there with all that suspension and power while I'm busting my ceramic hip breaking trail and pulling you through the nasty bits. Boy, I should get me one of those fancy Katooms for next year:evil


    fasteddy
    #18
  19. Drif10

    Drif10 Accredited Jackass

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    :stupid

    Wasn't gonna dime you out Brian, but you asked for that one.
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  20. Mack

    Mack Gone, but never forgotten. RIP, Mack...

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    Ehh, The Canadian's are at it again! :rofl
    #20