'99 KTM 640Adventure-R rebuild time

Discussion in 'Thumpers' started by Low594, Mar 22, 2010.

  1. Low594

    Low594 Adventuring Creep

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    Well, I got myself another project bike! A little more of a project than I was hoping for, but thats the way these things go! While I am new to KTMs and singles, I am not new to riding (17+yrs) or to building motors (4 or so moto, 5 or so small car). My reluctance comes from not knowing where or who to source parts and such from, and also never having a KTM or single open. I have been trying to collect info from ADVRider and now from here. I did get the owners books with the bike and I also ordered the KTM Repair Manual.


    What I know from previous owner:
    -unknown mileage, guestimate of 15,000 kilometers; the IMO has a loose wire and resets itself, soon to be fixed, I believe

    -piston ring broken and shut engine down immediately, approximately 2 yrs ago; sat for a few months before getting replaced; owner rode bike roughly 1000 miles and was hearing a noise that made him nervous and the bike has sat since June 2009


    What I have found:
    -carb orings were dried up and leaking; could be the reason or one of the reasons I couldnt get the bike to start; I sent a message to MotoLab for a titanium needle, orings, stainless bolts and other bits and ordered the Mixture Screw from Stenhouse. I also contacted Boyesen and unfortunately they do not make a SuperBowl for the BST40

    -head gasket was leaking, but from the water jacket to the outside of the cylinder; so it was probably tightened down without proper torque, but close

    -the thrust washer between the cam and the large cam bearing was broken, looks like the retaining clip next to it was damaged and cause the thrust washer damage

    -the cylinder wall has aluminum embedded in the nikasil, most likely came from the previous piston; hoping to find a local machine shop to work with

    -the piston is scored on the skirt, matching where the aluminum is embedded into the cyl; also the bottom is badly burned; so time for a new piston!

    -the piston pin is a lil bit sloppier in the small end of the rod than I'd like to see, but I haven't really looked into whether or not its the pin, rod or bushing, does it have a bushing?


    I am on the line as to whether or not I should just do the topend or do a full tear down and at least inspect it thoughly. I'd like to get the bike up and running ASAP, but on the other hand I want it to be the best it can be and last a while, so I am leaning towards a teardown.

    I intend on using the bike for daily riding as well as long distance trips (ADVRider WestFest in Montana, [1100 miles one way] in July 2010]. I want reliability and longevity vs hotrod, I have the Ducati for that! I intend to take the time to make the motor as efficient as possible.

    What I would like to know is:
    - One of the camcover bolts has a locating bulb/knob on the tip. It was located on the left side just in front of the water pump. Where does it belong?
    - What improvements and upgrades should I be considering?
    - Are there weak points/issues to look for?
    - Should I put a High Flow head on it, if the price is reasonable?
    - Should I put larger valves in it?
    - Better cam to consider?
    - I've found a few missing bolts, washers, dowels and misc parts that I will need to order from a dealer, who has good pricing, stock, shipping, etc? Stateside would be faster I assume.
    - I've read of Engine Dynamics, who is a short drive from me, so I will be calling them on Monday to see what they can help me with. Who else should I get in contact with?
    - What else have I missed that I should consider?


    Is there anyone in the Nor Cal area who has experience with these motors, that wouldn't mind taking a look from time to time? I can come to you.

    Thank you all!
    #1
  2. Low594

    Low594 Adventuring Creep

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    [​IMG]
    Here is the head, not too bad, I've seen worse! Notice bottom right, where the head gasket was allowing coolant to squeeze by to the outside.

    [​IMG]
    Spark plug, bit rich, not bad considering the 162 main jet at sea level. I know it looks like it, but it is not cracked, just dirt residue at the edge of the boot.

    [​IMG]
    Cam assembly with broken thrust washer.
    #2
  3. Low594

    Low594 Adventuring Creep

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    [​IMG]
    View from top of cylinder, showing aluminum deposits and scoring

    [​IMG]
    Top of piston looks decent

    [​IMG]
    Hard to see, but there is deep scoring on the skirt from the aluminum deposits on the cyl wall. Also, look to have been way over heated.
    #3
  4. Low594

    Low594 Adventuring Creep

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    I did get more time today to check out the crank and con rod. I found that the gap between the con rod, shim and crank was .033". Plus, we were able to pull the con rod up and smack it down and could hear a smack of metal hitting metal. Doesn't seem good to me, but just to be sure I am going to pull the motor and go see Engines Only, a local shop that does only thumpers, mostly XR/XL.

    I'm really hoping to not need crank work. But I would rather spend a bit more time and more and know exactly what I have for a motor.

    I'm wondering if the newer cranks will fit and what it is that they did to dampen the vibs. More research! I figure if stuff has to be replaced it might as well be an improvement!

    Also, need to look into Crankworks, Falicon, Carillo and APE/BigBoreThumpers, and see what each can do for me, well besides relieve me of the green in my pocket!
    #4
  5. Low594

    Low594 Adventuring Creep

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    Last night when I pulled the motor, I found a pair of switches in the motor with nothing run to them?!
    [​IMG]
    [​IMG]
    This is the right side of the motor, just above the frame, notice the oil filter access. The middle switch had a wire going to it, (un)fortunately it was heatshrinked well, so I couldnt get the wire color to confirm it is the neutral light. I would think that if the middle is the neutral sw. Then the other two are monitoring parts of the tranny as well. If that is so, wouldn't one expect to see 6 switches (1 for neutral and 1 for each of 5 gears?) or would 3 switches give you 1 for neutral and 2 switches covering 2 gears each, leaving 5th having no light? I am probably thinking too much on this! I just figure if they monitor something useful, say oil pressure, I'd like to make use of that!:evil

    -Is the middle switch indeed the neutral switch?
    -What are the other two for?
    #5
  6. Tseta

    Tseta Lost

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    Middle connector is for neutral wire, the other two are for 2nd and 3rd gear. The signals from those are used in a EPC (electrical power control) module, something to do with emissions or drive-by noise or such. This EPC is not fitted to all bikes (depending on market) and most people remove it anyway, as it diminishes rapid throttle response in 2nd and 3rd gear. Creeper has written a little bit more about EPC here.

    Interesting rebuild thread you have going on. Looking forward to more updates.

    Cheers,

    Tseta
    #6
  7. Low594

    Low594 Adventuring Creep

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    Thanks Tseta!

    The more I thought about it, I was really hoping for engine & tranny oil pressure!
    #7
  8. Seikkailu_R

    Seikkailu_R Been here awhile

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    If you take these switches off from engine block, please measure how long is part that go inside of engine...

    Looking for good place for engine oil temperature sensor...
    #8
  9. wrk2surf

    wrk2surf on the gas or brakes

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    buy a prox con rod repair kit and take it to a cranshaft rebuilder and have him balance it.. cheaper than a new one

    when you get that far you will have to maybe reshim the crank to the cases..
    #9
  10. Low594

    Low594 Adventuring Creep

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    Sure, I can do that! Altho, it sounds like those are switches for the 2nd & 3rd gears, which means that they are in the tranny portion, so that might work for tranny oil temp, but not engine oil temp.
    #10
  11. Seikkailu_R

    Seikkailu_R Been here awhile

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    No separated teransmission or primary oil on LC4...
    #11
  12. Low594

    Low594 Adventuring Creep

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    I'm leaning towards sending the crank and rod to Crankworks in Tempe, AZ, for a new con rod and to have the crank rebuilt, balanced and welded.

    I went by Moto Lab today to pick up all the orings, needle, slide, etc to rebuild the carb. Derek and I spoke for a long time and looked the motor over. Looks like the motor was experiencing detonation, which is what tore up the piston and cylinder. Big thumbs up to Moto Lab!!

    I'm thinking that may have played a part in over heating the oil and wearing out the crank prematurely.
    #12
  13. Low594

    Low594 Adventuring Creep

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    Hmmm?! Ok, I assumed since they have seperate tranny and engine drain plugs that they had seperated sections.
    #13
  14. Seikkailu_R

    Seikkailu_R Been here awhile

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    Big one with mesh and magnet is on clutch area, and smaller with only magnet is on transmission side.
    On -02 model and later.
    To -01 small plug is just next to big one.

    If i remember that right...
    #14
  15. Low594

    Low594 Adventuring Creep

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    Yep, that's right! Thank you!
    #15
  16. Low594

    Low594 Adventuring Creep

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    I tried a search here and google, I have also been working through the LC4 Index and cant find any info on a comparison of the heads. I gather that my '99 has the smallest valves, then it seems around '01 they changed the valve size, then there is the Hi Flow head. Has anyone else found or know info on this?
    #16
  17. Seikkailu_R

    Seikkailu_R Been here awhile

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    Here...

    Intake valve 36mm, from 1994 350 SUPER-COMP to 2007 660 RALLYE FACTORY REPLICA

    Exhaust 30 mm, from 1994 350 SUPER-COMP to 2002 640 LC4-E Super-Moto

    Exhaust 32mm, from 2001 660 RALLYE to 2007 660 RALLYE FACTORY REPLICA

    Something like this...
    #17
  18. Low594

    Low594 Adventuring Creep

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    Thank you!
    #18
  19. wrk2surf

    wrk2surf on the gas or brakes

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    the rallye valves and springs are used on ALL 03 and later 625 and 640s.

    people have been known to go larger...
    #19
  20. Low594

    Low594 Adventuring Creep

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    I am working with Moto Lab and with his previous work on a 2000 640A he found that with these early motors are restricted via the exhaust, valves all the way out to the pipes. What I am wondering about now is what "Hi Flow" means on these. Is it just larger valves or larger valves and improved exhaust runners? Has anyone done a side by side comparison?
    #20