LC-4 shimming the Crankshaft

Discussion in 'Thumpers' started by gunnerbuck, Apr 23, 2007.

  1. gunnerbuck

    gunnerbuck Island Hopper

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    I'm in the process of installing a new crankshaft on my 03 Adventure and have a quick question on the crank shims. With the shims I have on hand I must use 2 - 0.3 mm shims + 1- 0.1 mm shim in order to get the correct play. I know that the shims on either side should be equal but does it matter that 1 side has 0.1 mm more shimming than the other? I would think not when you take into acount the conrod play as well as the play at the wrist pin.
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  2. halfcab

    halfcab Been here awhile

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    The small end of the crank rod does not have to be 100% in the center of the wrist pin boss.
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  3. creeper

    creeper Still alive...

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    The crank will still find it's center, it just has less lateral travel to the thrust surface on one side vs. the other.
    As long as you have your 0.03mm ~ 0.12mm total lateral play (and I'd be prone to lean toward the loose side of the spec) that 0.1mm shorter side shouldn't be an issue.

    By the way, what is your total EP with the shims you have?

    C
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  4. laramie LC4

    laramie LC4 crash test dummy!

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    how are you taking your measurements ???

    0.1 isnt that much of a diference, so id be really thourough about checking my numbers. make absolutly shure they are correct, and make sure you always use the loosest numbers, not the tightest or averages.

    if i was you, id just use the 2- .3mm shims and call it good. i made the mistake of trying to add that extra shim when i rebuilt my engine and ended up making it too tight. everything was fine and the cranks turned smooth and easily till i torqued the case bolts, then it tightened up and wouldnt turn. then i was stuck trying to remove the cank bearings again to re-shim it. not the easiest thing in the world to do unless you have special tools.

    i personally dont like the idea of having diff measurements on either side of the crank either, i dont think its a good idea. the manual is very specific about that.

    good luck,

    laramie :beer
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  5. gunnerbuck

    gunnerbuck Island Hopper

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    Slapped her together and she's too tight, so I manufactured 2 pullers to get the bearing races back off. I used a borrowed digital caliper to take the original measurements which gave me .04 play, this time I'm going to use my own dial caliper to do the recheck. I'm thinking that even .6 may be too tight judging by how things looked when the cases went together. Probably turn out needing a .10 mm + .15 mm on each side for a total of .50 mm but I'm going to spend a long time measuring to make sure because getting those races back off is major ass pain. This time I'm going to use a small piece of rod to measure the bearing to case centre straightedge contact, I will cut the rod a slight bit long, file a bit off at a time and then mike it when the length is correct.
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  6. jfn68

    jfn68 Banned

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    Just a thought,im sure you know,you got the gasket between the case halves when you do your measurements?
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  7. halfcab

    halfcab Been here awhile

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    Not to hijack this post....but is it easy to press the crank pin (main rod bearing) out of the LC4 crank shaft.
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  8. gunnerbuck

    gunnerbuck Island Hopper

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    I never bothered pressing out the crankpin as the price for a whole new assembly is only about $100 more and you get an updated crank {improved?}.

    jfn 68- If I forgot to take the gasket in acount when measuring the play would be greater.
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  9. gunnerbuck

    gunnerbuck Island Hopper

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    Did the method of measurement I mentioned in the above post with the rods and it seemed to work pretty good. I was way over on the last measurement as the new measurement showed me needing a .15 mm shim on each side. On the plus side I have made the tools so if I ever need to play with the crank again it shouldn't be so difficult. I pulled the races off my old crank and the shimset was also .15 mm on both ends so I'm pretty confident that shes ready to go back together.

    Thanks for the feedback and advice.....

    David...
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  10. halfcab

    halfcab Been here awhile

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    I understand your thinking and would do the same...but what is updated and improved about the newer cranks.

    I ask about pressing the crank pin out because I was thinking about balancing the crank if I ever had to pull the motor apart.
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  11. gunnerbuck

    gunnerbuck Island Hopper

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    The new crank is definetly different than the old. The old crank side plates were round as to where the new crank has cutouts on both sides. From the side it looks like a 2/3 moon with a spur jutting up in the middle where the crank pin attatches. The new crank could possibly be lighter and I should of weighed the difference but now it's in the engine and shimmed properly. I'm just assuming that this crank is improved. Why does KTM make changes? Usually they try to change things to improve the design. I have found one advantage so far with the new crank and thats with the cutouts you can fit a normal size dial caliper to measure crank width. Another could be that the cutouts may scavenge more oil off the housing floor and bring it up to give additional oil to the bearings.

    I was lucky to have the original crank run pretty smooth but if you have a real shaker version I can see trying the balance idea.
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  12. gunnerbuck

    gunnerbuck Island Hopper

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    Well I fired her up for the first time this morning after yesterdays marathon reassembly session and a half second push on the button was all it took. I adjusted the idle and waited for the frame to overflow oil and then put the plug in. No funny sounds coming from the engine so I took it for a spin around the block and then checked for oil leaks. I noticed right off that the engine runs very smooth considering the new parts are not set in yet. This leaves me wondering if the new cranks are better balanced right from the factory or if I had the luck of the draw. I then went for a 40 KM ride and everything seems ok with the engine running quiet and no unusual sounds. I am running regular 10/40 M/C oil for the break-in period and then will switch back to synthetic after that. The shifting is still very good with the standard oil as I notice no difference. One thing that did happen in the time that the bike sat idle is the fork seals let go as I forgot to bleed the air from them when I parked it and when I did after I noticed the leakage there was quite a pressure build up in them. So new seals will be here Tuesday. Anyways so far so good.......
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  13. halfcab

    halfcab Been here awhile

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    Glade to hear it's up and running. :clap

    From what you said the difference in the two cranks were I thought it would be smother. I was surprised to here they had that much weight at the crank pin to start with.
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  14. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Badda-bump.

    I'm finally getting my lazy, procrastinating butt in gear and putting my 97 Adventure back together. I'm now facing the crank bearing removal and came looking for advice.

    Can anybody describe to me what this magical bearing-heating tool looks like? Is it just an oven-heated clamshell of aluminum or steel that you clamp around the bearing? It seems like it would be tough to deal with a 350-400F lump of metal while trying to bolt it to the crank.

    I'm tempted to just grind a lip into the edge of the old bearing race and use that to clamp & pull it off. My worry is needing to go back and shim the new bearings afterward. :eek1

    Help?
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  15. gunnerbuck

    gunnerbuck Island Hopper

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    I made 2 pullers {1 for each bearing race} out of 1-1/2" steel pipe. I cut 2- 8" sections that were threaded on one end and installed end caps with drilled centers so I could screw them to my slam puller. With the open end of the pipe I cut 6-8 lengthwise slots and installed an automotive muffler clamp over the pipe. For the one race this worked like a charm, heat the pipe and slip it over the cool race, tighten the clamp and a couple slide hits and off she comes. For the other race you must heat and expand the pipe to get it to fit and install a larger clamp as I think the race has about an 1/8" larger D.

    I first tried to make a copy of the KTM puller and gave up after a couple tries. It looks like a chunk of flat steel with the correct D hole drilled to the edge with a cutoutslot to allow it to pinch the bearing. 2 handles allow you to slip it over the bearing and put twisting pressure to pinch the race and lift it off.

    I will post a couple pics of my puller later today.....
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  16. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Ahhh...I wasn't even thinking of a round pipe, puller. That's what I needed to know. Thanks.

    I think I'm going to grind this one to pull it and try to just reassemble. If the shimming is off, then I'll have to make the tool to preserve the new bearings.

    The shimming shouldn't change. The same crank is going back in, it hasn't been disassembled and the bearings won't have that much variance.
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  17. gunnerbuck

    gunnerbuck Island Hopper

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    [​IMG][​IMG]
    Crude but it works....
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  18. Donkey Hotey

    Donkey Hotey De Jo Momma

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    But who cares if it did the job? Good on ya' for coming up with that. The cheap solution is the best solution when it works. Did you preheat the pipe in the oven or did it work cold? Did you try it cold?

    One main bearing came right off (snug, sliding fit). I'm going to put the other one into my lathe's 6-jaw chuck and try to twist it before I go any further. It might just come loose.
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  19. gunnerbuck

    gunnerbuck Island Hopper

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    I put the crank in the freezer and gave the pipe a shot of heat with the torch..... To slide it on tighten the clamps and whack the puller took about 30 seconds and the race popped off... There was no way they would budge when I tried it cold....

    I again put the crank in the freezer and warmed the new races with a heat gun and they easily dropped into place but I had a piece of padded pipe ready just in case they needed persuasion....
    #19
  20. bmwktmbill

    bmwktmbill Traveler

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    You guys are my heroes.
    b.
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