About to pull apart a lc4 640 engine

Discussion in 'Thumpers' started by Ktm640, Sep 24, 2012.

  1. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    Right I have obtained a 2006 engine for my lc4 that is going to replace my dead black engine the only problem this engine has damage to the banjo bolt on the front of the engine.


    So I'm going to get a new set of cases on a good deal and do. Complete strip of my engine and rebuild into the new cases.

    The engine has only done 5600 miles so I'm not expecting any nightmare problems (fingers crossed) so with getting the cases and other associated seals and gaskets does anyone with experience on stripping the lc4 engines knows of other parts I will have to replace on a rebuild.

    I'm also aware that I'm going to need some extra tools:

    Depth gauge for the crank shimming

    Vernier caliper for crank measurement (will bog standard do it or do they need to be deep jaw ones)

    Dti for measuring the crank play.

    And anything else anyone can think of, I have quite a good range of tools in my toolbox that I have recently rebuilt my bike with but the tools above I'm going to buy again as I'm wanting a more accurate set.

    Also any other hints and tips would be greatly appreciated and I have been studying the KTM engine manual and gunnerbucks,testas rebuild threads.

    Thanks ross....
    #1
  2. jon6.0

    jon6.0 Been here awhile

    Joined:
    Jun 7, 2008
    Oddometer:
    546
    Location:
    Phoenix
  3. clintnz

    clintnz Trans-Global Chook Chaser

    Joined:
    May 17, 2004
    Oddometer:
    3,662
    Location:
    Rotoiti, New Zealand
    Depth gauge is just a nice to have. I just filed down a rod then measured it with verniers.

    You will need bearing race pullers if you have to adjust the crank shimming.

    You will need deep verniers to measure the crank width.

    The KTM gasket & seal set is very comprehensive.

    Cheers
    Clint
    #3
  4. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    Yeah forgot about the pullers I need to get them to get the primary gear etc off so will need to purchase a gear puller

    For the crank are they special bearing pullers or just general two or three leg puller.

    I'm presuming that the crank will need reshimming with a crankcase change or not!!!!
    #4
  5. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475
    You can find no solution to the damaged banjo bolt besides case replacement??? :eek1
    #5
  6. clintnz

    clintnz Trans-Global Chook Chaser

    Joined:
    May 17, 2004
    Oddometer:
    3,662
    Location:
    Rotoiti, New Zealand
    Yup. Special pullers:

    [​IMG]

    You can't get behind the main bearing races on the crank so you heat these up & squeeze em on. Chill the crank in the freezer first. They would be better made from aluminium as the factory ones are but I couldn't find any thick enough alu in the scrap pile that day :wink:

    If putting the same crank back in the same cases I doubt you'd need to re shim.

    The flywheel puller was quite reasonably priced ex KTM when I got mine.

    Cheers
    Clint
    #6
  7. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    The replacement engine i got was from a front impact bike and the frame snapped and swiped the front of the engine snapping the banjo bolt off and taking a chunk of aluminium out of the casing right next to the banjo thread so I have tried to reface the surface to get the oil line to reseal but it still leaks.

    I could get it welded and refaced by a machine shop but I'm also aware that the cases may of took some damage (structural/fractures) from the frame snapping so I'm changing for peace of mind as well as to fix oil line problem.
    #7
  8. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    Yep they look great clintnz don't suppose you have the inside diameter of the hole for the bearings as I have not stripped the engine yet so do not know the bearing o/d.

    Isn't steel better for them like you made as that would retain the heat better so as to enlarge the bearing also how thick did you make yours.

    Thanks Ross....
    #8
  9. clintnz

    clintnz Trans-Global Chook Chaser

    Joined:
    May 17, 2004
    Oddometer:
    3,662
    Location:
    Rotoiti, New Zealand
    I'll measure them up tonight for ya, send me a nagging PM if you don't see a reply by Friday.

    While Aluminium is only about 1/3 as dense as steel it has twice the specific heat capacity & is 4x better at heat transfer, there would also be less chance of damaging the bearing races than with steel.

    Cheers
    Clint
    #9
  10. johnno950

    johnno950 Long timer

    Joined:
    Jul 17, 2010
    Oddometer:
    1,076
    Dont forget to add the thickness of the gasket between lower caseing halfs when doing your axial/endfloat on crankshaft,easy mistake to make if not reading manual correctly,always good to get measurements/results spot one first time so dont have to remove bearings/adjust shimming.A good quality internal micrometer read by a good tradesmen is worthwhile.
    #10
  11. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475

    I gotta think I'd be sealing that leak and running the engine for a bit to see . These engines are pretty built, beefy things. It runs now without bad noises? I've seen alot of case repairs, even on newer KTM ATVs cracked in racing accidents with other ATVs where the swingarm pivot cases cracked thru. A weld and grind and back to business in the next moto!

    How about a pic of the damage and a pic of the crashed bike?
    #11
  12. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    Tried to fix the leak by refacing the surface but to no avail.

    The bike was not mine I bought the engine off a guy who had the crash it was a front on impact into a car.
    Destroyed the front wheel, cracked the fork clamps, which in turn the folded the wheel into the frame which in turn then snapped and took a chunk out of the casing. The actual damage I thought might be a easy repair but it just pisses oil out of the front oil line banjo bolt position.

    And all the mechanics and machine shops round by me will not touch the case without it completely stripped down.
    So if I have to strip the engine might as well just swap the cases as a weld may fail further down the line or worst case the weld may warp the alu case somehow.
    #12
  13. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475
    Toss us a pic of the damage. You never know what advice will turn up. I've seen cases welded in the pits while the bike was still completely together and still warm from racing so much can be done. Finding the right guy might be tougher.
    #13
  14. clintnz

    clintnz Trans-Global Chook Chaser

    Joined:
    May 17, 2004
    Oddometer:
    3,662
    Location:
    Rotoiti, New Zealand
    The KTM gasket set I got came with 2 case gaskets, so I bolted the cases together empty with a gasket in place to measure up for the crank shimming by filing down an alu rod to just fit between the bearing races. After fitting the crank it came out in spec 1st go but only just, at the tight end, I was being fussy so I had another couple of tries before I got the end float where I wanted it at 0.11mm.

    My puller ID's are 43.9mm & 40.5mm. This is borderline loose when heated up though, you could probably go 43.8mm & 40.4mm fairly safely, make them to fit if you can, with a very tight fit when cold. With alu you would need to allow even more for thermal expansion. They need to be 20mm deep, a bit thicker won't hurt.

    You may get lucky & not need to re-shim anyway - I would bet that the tolerances on the cases from batch to batch are probably pretty tight, the shims are there to allow for variation in the pressed-together crank assembly, so the same crank & the same bearings in different cases may not be a problem.

    Cheers
    Clint
    #14
  15. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    That's awesome clintnz I'm just putting my old lathe back together at the moment so will be giving it a shot when I get it built just need to check how accurate my lathe is going to be and if its not ill get a mate to knock me some up on his lathe.

    Will let you know how i do at making them....


    Just another thing how hard was it to pull the bearings did it take just a pull/yank or was some persuasion involved.
    #15
  16. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    Here is some pics done on the iPhone so not the best

    Have tried refacing with a facing tool but the problem was trying to get the tool to stay flat with hardly any surface to stand against and the bogged tool I made to mount the facing tool was just crap so got a reasonable surface on it and took down about 2mm but still could not get a decent seal.

    [​IMG]

    [​IMG]

    As you can see its quite close to the threads but there is a bit of metal still left but this is not enough to make the seal on the copper washer and the problem is after welding is getting it faced off properly so the oil line does not piss oil again.
    #16
  17. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475
    There is no way I'd be stripping that down for that damage. Have you tried a simple epoxy repair yet? Maybe even a rubber gasket and an epoxy smear? Welding on a flat aluminum plate/washer perhaps, larger outside diameter to the edge of the flange maybe? That looks too minimal a hit to do anything serious inside those cases IMO.

    A better fab guy will hopefully chime in or I'd start a new thread on just how to repair that in the "Garage" section. I'm betting you can avoid a full inner heart transplant/case split.
    #17
  18. clintnz

    clintnz Trans-Global Chook Chaser

    Joined:
    May 17, 2004
    Oddometer:
    3,662
    Location:
    Rotoiti, New Zealand
    I'd be having a go at glueing the banjo in with some sorta industrial epoxy to seal it before I launched into replacing the cases on that one. It's not like you have to remove that oil line very often. The oil pressure is not high on the LC4 as there are no plain bearings.

    When pulling off the inner main races you need to work fairly fast - crank well chilled, bearing puller good & hot, I used my camp cooker. Hold the crank securely. Clamp down on the race as hard as you can to maximise heat transfer & try to turn it slightly either way but don't slip it on the race, you are just feeling for when it comes loose, it will take a few seconds before the heat gets into it & it does come loose, keep a tight grip, twist it a bit & keep the puller aligned as you pull it off.

    Cheers
    Clint
    #18
  19. Ktm640

    Ktm640 Adventurer

    Joined:
    Oct 24, 2011
    Oddometer:
    19
    Tried epoxy as well, the oil just got underneath it and blew it off
    #19
  20. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475
    Try a thread in garage section. It might save you alot of work.
    #20