Yesterday I pulled out the engine (lots of pics)

Discussion in 'Old's Cool' started by R-dubb, Sep 10, 2006.

  1. R-dubb

    R-dubb Dubbious Adventurer

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    know we've seen this movie a few times before, but here goes with a photo review of work in progress on my efforts to hot rod a '93 R100GS. I'm replacing the cylinders, pistons, heads, carbs, cam shaft with upgraded R100S parts and a 1050 pistons kit. I collected all the "S" gear very inexpensively on IBMWR. The piston kit is from CC Products (aka San Jose BMW).

    Months ago I pulled the transmission and stacked a big Ole pile'O parts on the back bench. Been cleaning up the engine cases and few odd jobs, but mostly the rig has been collecting dust waiting for parts orders and machine work to be completed

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    Took out the engine and strapped it to my bench. No tricks. I just taped the frame rails and used wood blocks under the oil pan to make pulling the mounting bolts straight and balanced. Used a ratcheting strap to attach the engine to the table.

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    Previously, most of the engine work I've done on airheads has been in the frame. After seeing Dave Gardner do his work on a bench, I decided this is a much better way to go. So far, I really like the convenience.

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    Very first little job turn to crap instantly. Since I bought this bike with intent of upgrading the engine, I had not changed the oil filter yet. Good thing too. One of the cover bolts was seized and broke off instantly as I tried to open it. Then, like an idiot I sheared a screw extractor. Turned out fine though. I managed to twist out the stub and then was forced to drill out and re-tap the bolt hole from scratch.

    Timing Chain Cover Removal

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    Stator pops off with little effort. I just popped out the brushes. Freed all the wires and pried it off making sure to keep the pieces merged together.

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    Rotor takes a little more doing. There is a double thread on the bolt. You remove the bolt, then insert a 6x50mm piece of rod (a bolt shaft) into the hole and re-torque the original bolt using the threads as a puller. Works fine, but took more torque than I expected to pop the rotor. The rotor does pop and can eject with a lot of force.

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    All that is left is pulling a few more wires and removing eight of nine bolts from the timing case and apply some persuasion in the form of a rubber mallet tapping in circle around the case. I don't think this sucker had ever been pulled previously and was glue in place by the gasket very tightly.

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    Head and Cylinder Removal

    This part I've been through before so it's familiar. With the engine at TDC. I remove the head nuts from the valve gear and put each set in a plastic bag labeled for location, keeping the rockers all together on the blocks ready to put back. Pull the push rods and then tap the head to bust it loose. Very easy with little force.

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    Yukkk...both the pistons and the combustion chambers were heavily caked with carbon. Not unusual, but not good either. Never mind, I'm not reusing these jugs or pistons in the rebuild.

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    I'm very surprised this push rod seal never leaked much (see big crack on right).

    Next I tap the jug loose and pull it across the piston until the wrist pin is clear. At this point, open the cir-clip on one side and slide the pin through and out. Piston then comes off while still inside the cylinder.

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    Tape the bore edges to prevent damage

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    So far so good. Much easier than pulling apart an oilhead!

    Cam Shaft Removal

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    Use a magnet to remove the cam followers.

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    Tie back the cam tensioner with a zip tie.

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    Rather than taking the chain off first, I put tape on the edges of the case and used a pair of screw drivers to press the cam shaft and sprocket loose from the engine. As soon as it moves a little, there is enough space to open the master link and slide it out from behind the sprocket.

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    Interestingly, my cam shaft has a pronounced flat spot on the Left hand intake lobe. I have no idea what could cause this. Small enough to grind smooth, but since I'm replacing the cam with the sport version, no need.

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    That's it for now. Next chapter: The Rebuild

    cheers
    #1
  2. nomiles

    nomiles Sledge-o-matic

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    Cool photos, Rick!

    I've never seen a boxer engine apart before, thanks. :thumb :thumb

    I can't wait for the blower installation pics. :D
    #2
  3. Anorak

    Anorak Woolf Barnato Supporter

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    That cam is shot. The way to repair it would be to weld it up with hard-face rod and grind it. A flat spot like that has gone through the hardened outer layer. Good thing you have a replacement. What did you pay for the sport cam? I have an N.O.S. one and if my R100RS already has the 336 then I have a redundancy.
    #3
  4. sharkey

    sharkey XLV750R

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    Yep, that's a sad looking camshaft. Might be handy if, as you say, you wanted to get it built up and custom ground. Hmmm, I wonder how the 336 would go in my GS :-)
    Hey R-dubb, what's the difference between the 100GS and the 100S grind?

    -----sharks
    #4
  5. BareRider

    BareRider Adventurer

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    Great pictures! Thanks for all the hard extra effort to take and post them.
    #5
  6. Boojum

    Boojum I Miss the PartyBoss

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    Thanks for the Post, R-dubb! I'm always wanting to learn more about these bikes! So what is it you have in mind for the Motor, now? :wink: :ear


    Boojum!
    #6
  7. Rad

    Rad Done riding

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    Rick

    Yur photo wrench'n reports are always great :thumb

    I'm look'n forward to the rest

    rad :nod
    #7
  8. datchew

    datchew Don't buy from Brad

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    :lurk
    #8
  9. R-dubb

    R-dubb Dubbious Adventurer

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    Thanks to you and FB for condemning my cam shaft to the circular parts bin.

    I wonder what gives with the melt-down of the intake lobe on my cam? Perhaps the former owner ran the engine for a long time with loose valve clearance. This could make some chatter in the push rod. The lifters all look perfect, no nicks no wear pattern. They are clean. There are some score lines around the diameter of a couple of push rods about two inches up the shaft. It looks like the interference occurred at the head gasket. Must have been ether at the bottom or top of the stroke. I'll post pictures of that later. Could the pushrod scoring and cam failure be related? Over rev?

    Any thoughts out there?

    The new 336 cam cost me $135 at Chicago. I've had it sitting around for a while now. There are two cam grinds available. Stock GS is 308 degrees of opening. Sport is 336. In '79 (I think) BMW switched to a slip-in shaft end that eliminated the need to remove the oil pump for access to the cam shaft. The only model that came equipped with a 336 cam at that time was the R100RS. (The R100S had the same grind but used the earlier fittings.) The lift on the 308 & 336 cams are identical. This information is incorrect. No BMW's ever came stock with a 336 cam. The lift is also somewhat higher than stock. Increased opening duration allows for more flow and makes the valve opening more abrupt (steeper angle). The 336 sport cam part number is:11311336393. Hopefully I'll be happy with it. The only downside I've heard about is erratic idle. Requires perfect sync and well sealed carbs. We'll see.

    -dubb
    #9
  10. Stagehand

    Stagehand Imperfectionist

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    this is one of the reasons I keep coming back here.

    thanks, and great pictures!
    #10
  11. Rad

    Rad Done riding

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    You mean the TB thread in JM is not enough to bring ya back:lol3
    #11
  12. Anorak

    Anorak Woolf Barnato Supporter

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    Most likely bad oil killed your cam or a defect in the case hardening. By bad oil I mean oil that not been changed frequently enough. You are replacing the tappets as well, right?
    #12
  13. camgregus

    camgregus riding gently now

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    :lurk :lurk
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  14. R-dubb

    R-dubb Dubbious Adventurer

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    I considered replacing the followers. Still can, if I order some quickly. I kinda thought I would keep the existing. No discoloration of any kind. No scoring or wear pattern on the tops. Perfectly flat. Very smooth action in the bores. Jinx also stated they should be replaced with the cam. Why?

    BTW, the former owner provided excellent service records gave every indication that he was a loving owner. He was however the second owner and the original may have been lax. 1st owner put on about 25k on the bike in four years second put on another 20 in five or six. Service history includes major transmission work, decarbonization and a bunch of misc crap that goes wrong. I is slightly odd that the faulty oil filter bolt was very corroded and clearly had not been opened for a long time...
    #14
  15. Bernd Bauer

    Bernd Bauer Adventurer

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    Hi,

    according to the info I have the lift is NOT identical.
    Here you can find a table with the data of the 2V-cams
    http://www.mirotec.org/nocke_list.htm

    lift = Nockenhub

    Furthermore there is an official service bulletin about the 336° cam where
    this is stated too.


    Regards

    Bernd
    #15
  16. R-dubb

    R-dubb Dubbious Adventurer

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    You guys always have the better facts. What's with that? That data is indeed very helpful to understand what's going on. Don't read German but it looks like the ones listed with part numbers are BMW equipment. The others must be 3rd party. Looks like the 336 cam is a little more radical than I was imagining. I'll need to check carefully for interference. Can't imagine that will be a problem, but thank you so much for the correction.

    cheers
    #16
  17. Anorak

    Anorak Woolf Barnato Supporter

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    Replacing cam and liffter as a set is cheap insurance. They run in and wear to each other. Think about it this way, do you want to replace the cam again before you need to? I would be especially inclined to replace them because of the wear on your cam. Money spent now will be saved later.
    #17
  18. R-dubb

    R-dubb Dubbious Adventurer

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    I hear you on the cheap insurance part. Just to be argumentitive, if I can't detect any wear pattern on the existing lifter, that means they are harder than the cam surfaces. How could that be a problem? Am I missing something or are we just talking about conventional wisdom on the subject?
    #18
  19. Motomech

    Motomech Adventurer in Latin Amer.

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    Forth picture, drilling out the oil filter cover bolt, the peanut gallery seems to be feeling your pain. Too funny.
    Great post.
    Thanks.
    #19
  20. Anorak

    Anorak Woolf Barnato Supporter

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    Roll the lifter bases against each other. The should rock slightly because they are slightly convex. They can wear flat. Normal wear is still 40k plus miles of wear. You are putting in a higher lift longer duration cam which will load the tappets more. Aren't you building a higher performance engine? False economy.
    #20