640 LC4 - Is mine dying?

Discussion in 'Thumpers' started by scatland, May 22, 2013.

  1. scatland

    scatland Adventurer

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    I bought a 2004 640 LC4 Supermoto a few months back with 5600 miles on the clock, it seems to have had a shady history as far as servicing documents go and has only got proof from its first 600 mile service. It runs pretty well when warmed up and pulls like hell but seems to idle like a feckin harley :eek1:eek1:eek1:eek1

    this in itself doesnt bother me but I seem to be hearing (or imagining) a bit of metallic clattering from the engine. Im thinking and hoping the valves are the problem here and are just loose (no record of any valve work done on it) but i'm quite worried something is majorly wrong and it will explode at any minute :lol3

    I plan on taking this several thousand miles to greece and back in the summer so want to know if I have a grenade on my hands here..

    Any suggestions LC4 Gurus? :ear
    #1
  2. scatland

    scatland Adventurer

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  3. Droptarotter

    Droptarotter Long timer

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    Start with checking the valves...........if lots of clearance, the rocker roller bearings are probably shot.

    Do the water pump at the same time.

    What does the oil/ magnetic plug/filters look like?

    We have heard a lot of bikes that sound like this lately...........some have just needed valve adjustments...........some have needed a total rebuild.

    Cheers
    #3
  4. scatland

    scatland Adventurer

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    Took it to the KTM dealer today and the mechanic had a listen then told me all the 640s he's worked on sounded like this, apparently if it goes quiet I should start getting worried (tight valves) so with that worry gone he then pointed out the small leak in my base gasket that I hadn't noticed up until now :cry

    Probably just going to run it as normal and maybe reseal it when I do the valves and oil in 1500 miles. A small leak wont harm anything unless its literally spraying oil right?
    #4
  5. Foot dragger

    Foot dragger singletracker

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    Small leak is small stuff,but could get bigger at a bad time and make a mess.
    #5
  6. wrk2surf

    wrk2surf on the gas or brakes

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    1...do a FULL service replacing all the fluids, check and if needed adjust your valves... check the brake pads and...
    2....ride it like you stole it
    #6
  7. gunnerbuck

    gunnerbuck Island Hopper

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    I listened to your video/audio, and to me it sounds like you have excessive valve tappet clatter... Sometimes posted video exaggerates and amplifies the actual sound being produced... But from what I am hearing it would be worth doing a valve adjust to see if you indeed have excessive clearances...

    Like Droptarotter mentioned, if you find that your clearance is open past spec then there is a high possibility that your cam follower bearing is shot and needing replacement... The Norm on these engines is for the clearances to shrink with valve to valve seat wear...

    If you do check the valves and they are withing spec then your good to go and won't have to check them again for a while...
    #7
  8. Hair

    Hair Free to a good home.

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    I recently repurchased an 2003 LC4 enduro. I owned it many moons ago. Sold it to a guy who had track racing in his blood. He sold it to a friend of mine. And I bought it back from him.
    The bike needs a fair amount of work on it. But I am really liking the carb vs FI. So I think that the extra work is worth it.

    So what can I do to get a better understanding of the overall condition of my motor? I really don't have any good shops around. I am thinking of replacing my upper cam bearings.
    My concern here is how can I check to see if the main bearings are worn? The bike currently has 15000 miles on it.
    #8
  9. Idle

    Idle Been here awhile

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    Scatland, I'm far from being an LC4 guru or jedi, but your valves should/must be checked.

    If you've changed the oil already, it might be a good idea to change it again.

    This assuming it's only been changed once at the 600 mile service. It could use a flush if that's the case.


    Regarding the valves..
    If they are way too loose, as stated above, the CFB's should be checked.

    You need to pull the valve cover off to check them, and at that point, it might be a good idea to just replace them if you want piece of mind and have the $..

    The CFB's (cam follower bearings, or rocker arm bearings) can go for hundreds of hours without a problem.

    When the needle bearings wear to a certain point, one will escape, and it will seize and likely destroy your cam.

    Sometimes they can fail at a much shorter interval. The rocker arm end-play is critical to get right if you replace the CFB's.

    You need to put a feeler gauge between the rocker arm and the valve cover, then finger tighten the screw that goes through the shaft.
    Then tap the plug on the outside of the valve cover, then torque the screw down. Remove feeler gauge and do the other one.

    Good luck with your bike, and check the valves (yourself). It's a piece of cake..

    You really don't have enough hours on it to worry about the CFB's at this point. Around 10-12k miles is a good time to inspect and/or replace them.



    Hair, correct me if I'm wrong, but I thought the cam bearings are sealed?

    If they are, they should be fine for many more hours. Is it the CFB's you are talking about?

    I have checked my berg main bearings by taking the ignition cover off, and physically moving the flywheel in-out and up-down.

    You need to pull the plug maybe, and turn the engine over untill it's slack. It won't move for you unless it is at a slack point. TDC or around there and/or BDC or around there.

    Grab the flywheel with both hands and push it in and pull it out.

    It's tough to measure, you may just have to do it by feel. It should have a little bit of end-play, check the specs for your bike.

    Iirc, on my berg it's ~.5 mm. *actually I don't remember anything correctly and I'm guessing. The point is it HAS to have some end-play (in-out).

    Then grab and try to move the flywheel up and down and forward and backwards. You should have no play at all. If it does, start collecting parts and tools for a rebuild.

    After checking it both ways, get a second or third opinion by rotating the engine 180° until it's slack and then check it again and again for good measure.

    On the bergs, premature main bearing failures were or may have been caused by not enough end play from the factory. The LC4 engines don't have main bearing issues as far as I know.

    I'm somewhat of a n00b at wrenching on bikes, and never have owned an LC4 so I would advise checking with someone who is more familiar with them.

    Maybe creeper or another inmate has a writeup in the LC4 index thread on the main bearings and how to check them in situ.

    Or maybe there isn't one because they are bulletproof.
    #9
  10. Hair

    Hair Free to a good home.

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    Thanks for that reply.
    I adjusted my valves a while ago. Probably less than 10 hrs. Right from the get go I was worried that my intakes were to lose. They made a fair amount of noise. Then after reading this thread I was about to check my bearings. I still might.
    As far as the crank goes I will defiantly use your post.


    Oh by the way. Which berg do you have? I have had an 04 650 great bike
    and 10 570 and 10 390. Sadly to say I don't have any of them any more. There is talk that the 70 degree motor might come back. I loved my 570 I would like to get another.
    #10
  11. Idle

    Idle Been here awhile

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    2005's FS 650e, FE 650e, FE 550e... The 550 is in pieces, the engine is in the FS.

    I'm keeping them as long as possible.
    Or I might sell them all and get a 500exc and a 17" wheelset.

    I recall seeing your posts on the UHE site.
    #11
  12. clintnz

    clintnz Trans-Global Chook Chaser

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    Unless the thing has been run out of oil your mains should be fine at even 4x that mileage - they're big beefy roller bearings in there. My big end wore out at 60K miles - slight knock plus lots of metal on the sump bung was a giveaway - the piston, cam & valves were all due for some attention also but the mains were still fine.

    Cheers
    Clint
    #12
  13. scatland

    scatland Adventurer

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    Thanks for the replies guys, really helpful. Will be finding a weekend some time very soon to give the bike a big overhaul, the leak appears to have stopped (or it wasnt a leak maybe?) but I had to top up the bike with about 700ml of oil this week after 1800 miles since the change. Quite worrying.. they possibly hadnt given it enough at the dealership im hoping otherwise it is burning oil like a mofo :eek1

    In any case, this bike is going on a 4000mile tour in August (yes sumo touring :D) I and will be doing all of the work on this bike from now on. Hopefully I can manage this as I am a 20 year old student with less than stellar mechanical skills.

    next service will be -

    Pull carb, clean and rejet for akra exhaust (dont think was done as I think its running pretty lean - exhaust sounds like a machine gun on deceleration)

    Check Valve clearances adjust if necessary

    Oil and Filters

    Check Cam Follower bearings (not sure how I would do this)

    Check wheel bearings

    Install 18 liter tank and comfort seat


    and then I will hopefully be ready to kick some ass :gun1
    #13
  14. gunnerbuck

    gunnerbuck Island Hopper

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    The engine noise along with the oil use for sure would be a worrying combo.. I would recommend you have a leak down test {compression} performed to check on the top end condition..
    #14
  15. clintnz

    clintnz Trans-Global Chook Chaser

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    The valve clearances being really loose is a giveaway on that one. If you are worried, set them to spec then check again after a few hundred miles & see if they have opened up. FYI I've had around 30K miles ea on the 2 sets of cam followers I've removed, so if yours are toast at 5600mi you may also have other issues.

    x2 These motors are not known for using oil. Even just before I rebuilt mine with a well shagged piston it only needed 250-500ml extra between 3K mile services. It can be tricky to get the oil level right after a change so it might just be that.

    Cheers
    Clint
    #15
  16. scatland

    scatland Adventurer

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    So a quick update, found out Where the leak was coming from today. Seems it's from the braided oil line above the first oil filter. Should I just replace the copper gaskets for the banjo bolt or is this a known problem on lc4s?

    Pics of the leak - [​IMG]

    on another note going to go look at a drz400 with 4500 miles on it going for £2300 tomorrow (apparently an ex police dirtbike that was hardly used) I may end up getting this and selling the lc4 so I can do some dirt adventurin. Drzs are waaay more reliable than lc4s right? :evil
    #16
  17. gunnerbuck

    gunnerbuck Island Hopper

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    Take the banjo out, clean and inspect it... Sometimes installing the sealing washers gets overlooked or the bolt gets undertorqued... If the bolt has been over torqued it may have a split or become distorted... If it still leaks with new washers then replace the bolt, use a torque wrench to get it to the correct tension..
    #17
  18. scatland

    scatland Adventurer

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    Ok so... I tried doing the valve clearances today and ran out of daylight before they were done. had the feeler gauge in (Flimsy piece of shit) attempting to slide it around which was ok until I tightened down the jam nut which caused the adjustment to go completely out. also its an absolute PAIN IN THE ASS to get a wrench around the jam nut and I don't have a socket small enough to get into the top of the engine without touching the sides

    The bike is now sitting in my garage in pieces. looks like it will be the bus to work tomorrow :cry

    Also in regards to the oil leak, the banjo bolt had either been not tightened enough or had rattled loose. tightened it up with a torque wrench and no more leaky
    #18
  19. bmwktmbill

    bmwktmbill Traveler

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    Welcome to 640 land.

    Did you remove the fan(be gentle)? and the breather piping and the gas tank donuts.
    Clear the way.

    Use a long thin screwdriver to stabilize the threaded adjuster, get the jam nut a little tight with the box end of your 10mm combination wrench, check, fully tighten, final check, for all four adjusters.

    No long screwdriver?...go buy one. Get a little one too.
    Pick up a good quality 10 mm metric combination wrench too. A head lamp helps to see what you are doing.
    Make your own plan?

    Making a shortened allen wrench helps to loosen/tighten the valve covers

    Patience Prudence, you are learning, training your fingers, others will appreciate. I's like the piano.
    Practice!!!!!

    Haha, have fun.
    #19
  20. scatland

    scatland Adventurer

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    I followed the creeper guide on the valve adjustment, i was sure I had TDCC but now im thinking it was on the TDC Exhaust stroke. the piston was at the top of its stroke and everything seemed right when I closed it up. press the magic button and ... nothing.. it seems it wasnt able to turn over at TDC. pulled in decompression and gave it a couple kicks then eventually got the engine to turn over, the result was a VERY ticky engine

    See the video, I'm sure this is loose valves but they were right on .15mm when I had the feeler gauge in them :(

    <iframe width="420" height="315" src="http://www.youtube.com/embed/kcOtmy0B7ao?rel=0" frameborder="0" allowfullscreen></iframe>
    #20