Thumper Baja Trip

Discussion in 'Thumpers' started by Doc_Busa, Jan 10, 2004.

  1. Doc_Busa

    Doc_Busa Been here awhile

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    A few of you asked some bike specific questions and comparisons from our 2500 mile Baja trip (see Back from Baja under Rider Reports). Well, I was on the 2000 KTM LC4 640, my buddies had a '02 KLR650 and a '97 XR650L. I was very pleased with the KTM. I was a bit too tall and this resulted in droping it twice. I had upgraded the suspension with heavier springs front and back. It was by far the most powerful of the pack and the best off-road. On the highway the KLR seemed to have the advantage. I think all bikes were great at 65 mph and maybe even 70 mph, but above these speeds, the KTM really seemed to be working hard.

    Anyway, some of you asked me to talk about the bikes, so fire away if you have any questions.

    Doc
    #1
  2. ktmnate

    ktmnate Long timer

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    I noticed in some of your pictures that you had a boot over the front forks. Is this stock or did you add those? I have an '02 640 Adventure and it doesn't have them.
    #2
  3. Mack

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

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    Doc-Busa hope you don't mind my jumping in on this one. I have fork gaiters on my 02 and recomend them. Only downside that I can think of: You can't use a zip tie to check max travel, and it makes it harder to see fork leaks.

    Did the KLR or XR650L have any strong points on and/or off road that really overshadowed the KTM? Were all the bikes running stock gearing? I can't believe you only dropped your's twice, I'm 6'4" and I lost track of how many times I dropped mine on our last trip!

    Doc, have you uncorked your 640 yet? After adding the supermoto silencer and jetting mine on the dyno, I am able to wick it on pretty good. I don't always like the revs I'm seeing, but I will be be trying a Duke II countershaft sprocket on long road sections of future trips. Even loaded with the damn Touratech panniers sticking out into the airstream a couple of kilometers on each side, it pulls hard well into the 80 almost 90 mph range. I expect it had more, but this was fully loaded, on medium to tight roads running TKC's and the GS's weren't running any faster. Sadly I can't justify the FCR at present, maybe if I had an 03......:):

    I elected to leave my midrange strong, thus taking a slight hit on top end. Depending on how much you open up the airbox, you can slightly tune/alter the power curve. In retrospect I think I might have been better off by trying to max out the top end for on road use, and keep good throttle control down low, as I find I really don't ride this bike in the mid range much, and IMHO it certainly doesn't need more power off road! I thought I was kinda ignorant running it down so low, between 2200rpm and 4000 offroad, but the "Dirt Bike" magazine guys running the 24hours of Glen Helen on a LC4 625 SXC wrote: "Rule number one: don't rev it. On top, it was no faster than any other big thumper. But lugging the motor, you could stay in one gear for huge sections and the bike would seem 50 pounds lighter. "



    Like to hear your thoughts on this. Thanks, Mack
    #3
  4. papaduc

    papaduc Been here awhile

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    Mack
    I agree with the "lugging the engine" practice. When I ride off road with my 2 son in laws on the tight trails I stay in first gear and hardley pull the clutch in at verrrrrrry slow speeds. You can use these things like a tractor.
    When I ride by myself and do more open trails or 2 track stuff I find myself using a higher gear and lower rpm because it makes for smoother throttle control.
    Oh I'm riding a 2000 640E.
    Mike
    #4
  5. Doc_Busa

    Doc_Busa Been here awhile

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    Yeah, those are after market. They were recommended by the dealer for the harsh conditions in the Baja to help prevent seal damage from dust, mud, sand, etc.
    #5
  6. Doc_Busa

    Doc_Busa Been here awhile

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    No worries mate!

    It is kinda hard to say since the riders were quite different. One thing for sure, the KLR was running TKC 80's which were MUCH better in the mud then our Sahara 3's, so it was Advantage KLR. Without any question, the KTM had the best suspension, so in all other off-road conditions, the KTM ruled supreme. However, I and the KLR rider had much more experience then the Honda rider. The Honda rider dropped his bike 20 or more times! I believe all bikes were stock gearing... However, I want to verify this on mine. I was running 15-42, which I think is stock, but recently someone said 16-42 is stock, so I am not sure.... I was lucky to only drop it twice. Once was hilarious when I can around a tight bend to find the KLR on the side of the road due to an 18 wheeler coming the other way (this is on a dirt COW PATH). I had to hit the shoulder of lose rocks, couldn't stop and ass-ended my buddies KLR. Busted off the tip of my front fender then I droped it. The Mexican truck drivers had a good laugh though...

    But of course! I opened the top of the air box and replaced the carb with a TM40 pumper carb. I also installed a Doma racing silencer, but the head and mid-pipe are stock. Sadly, the install of the TM40 was more involved than I thought and required custom cables to be fabricated, the end result was that I left without it completely dialed in. I had the main jet too rich, so at wide open throttle, it would stumble. However, that accelerator pump kicks-butt! The bike pulls HARD off the line and in the mid-throttle range. I was able to get it close to 100 mph fully loaded. I just felt it was straining it a bit to hold it at 75 mph for an hour or so on the pavement. It may have been fine, I just feared for the longevity of my baby!

    The last dirt bike I had was an RM250, so I think I tended to ride the LC4 in the upper RPMs, especially on sand. I wanted the power there NOW and did not lug the motor. Sometimes on pavement I lugged just because I was exhausted and didn't feel like shifting...

    Let me know if you have any other questions or comments.

    Cheers!
    #6