Zundapp - I must be nuts?

Discussion in 'Old's Cool' started by bmwhacker, Mar 2, 2011.

  1. D.Bachtel

    D.Bachtel Been here awhile

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    Don't give up just yet, a little heat on the pistons and cylinders wouldn't hurt, but stick with a heat gun.
    I'm having my best luck with PB Blaster and Liquid Wrench even a little carb cleaner.
    Mix them all together and they seem to generate heat.
    Seems to be a little hotter and thinner that your normal oil. Must be carcinogenic. Sounds like we need more of a solvent than a lube.

    Got my cylinders off today, both bores look doable. Pistons had sticky rings (there are just 4 not 5?) but the LW mix freed them up.
    Grudgeon pins are a bit of a problem now. Even with a heat gun I can only slide them back and forth to the outside of the circlip groove on either side.
    3 out of 4 clips were missing one eye and it appears someone deformed the pistons while installing them without the proper tool.
    I've got some dimensions so I can begin making a removal tool at work tomorrow.

    If all goes well I should have the barrels blasted, painted, crosshatched and sized up by the end of the week.
    Then on to the heads. Planning on doing a hand lap, polishing the pistons and chambers, checking springs, guides and rockers.
    Lots of Liquid Wrench and PB Blaster to remove all remnants of the decades old putrid petrochemical varnish and sludge.


    Don in Nipomo
  2. bmwhacker

    bmwhacker Still on 3 wheels

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    If my next bout with the pistons is unsuccessful I will go to a more solvent based oil.
    The carcinogenic witches brew you talked about might be the key....as long as I don't blow myself up.:kboom
  3. tenderfoot

    tenderfoot PRJ

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    I realised on my way to work this morning that if the the big ends share the same journal the one would be on it's way in while the other is on it's way out, so the inward bound piston will draw the cylinder onto the crank case effectively jamming the whole lot in any case.

    Heating with a heat gun is an option, but I would imagine that the rings stuck to the cylinder wall would simply follow it out without letting go. No harm in trying. Heat gun is the way to go.
  4. tenderfoot

    tenderfoot PRJ

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    I checked, they do run seperate big ends at 180 degrees so theoretically one should be able to pop loosened cylinders.

    Came across some excellent sites, you maybe know them in any case.

    http://www.zundappfool.com/

    http://www.cybermotorcycle.com/index.html

    Good luck and keep us updated.

    Oh yes. Can you get to the big end bearing caps from underneath.? If you remove the caps you could then remove the cylinder with the piston and conrod as a unit to be pressed apart. At least you could let the cylinder stand on end for the penetrating oil to do its job.
  5. datchew

    datchew Don't buy from Brad

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    been watching your thread with interest.

    Maybe i missed it, but why can't you simply unbolt the cylinders and use some careful "wood-cushioned" hits with a mallet to either pull the cylinders from the pistons or get the crank to move or both?

    I admire your patience. I couldn't wait this long.

    +1 on the heatgun advice unless you're very experienced with a propane torch. leave the pistons, focus on the cylinders.

    :lurk
  6. bmwhacker

    bmwhacker Still on 3 wheels

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    The rod bearings are a roller type and live in a somewhat fragile appearing alloy cage. I'm a little nervous to get too "Western" with it.
    [​IMG]

    I unbolted the cylinders last weekend while trying to rotate the crank and did detect a tiny bit of movement on the right side. Only a millimeter or so. Care and patience are the order of the day for me on this one. Destroying anything salvageable equates to big bucks. Besides I have three other POS to keep me occupied if I feel the need to "fix" anything. :lol3
  7. Sniper X

    Sniper X De Oppresso Liber

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    Shoot,, just fit an electric motor, some batteries and ReName it DunZapp.
  8. Sniper X

    Sniper X De Oppresso Liber

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    Mihgt rig up a puller of sorts. One that has arms on the unbolted cylinder, and a pusher that pushes down on the piston. to PULL the cylinder off the piston keeping all load off the crank and associated fragile bearings.
  9. disston

    disston ShadeTreeExpert

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    I think I remember you were soaking in Marvil Mystery Oil? I love the stuff but don't think it's that good a rust buster. Lot's of homemade formulas or the best of the best is Kroil Oil. Find Kroil on the internet or nearby at gun stores. It's big with gun nuts.
  10. Center-stand

    Center-stand Long timer

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    Someone recently told me about a rusty nut busting mixture of 1/2 acetone and 1/2 auto transmission fluid. Worth a try.
  11. bmwhacker

    bmwhacker Still on 3 wheels

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    I''ve had good luck with the Marvel oil in the past but it looks like I'll need to go to a more aggressive meduim.....I'll try to hunt down some Kroil Oil.
  12. D.Bachtel

    D.Bachtel Been here awhile

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    Location:
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    Definitely Kroil, or even some Cut Thru. The PB does disolve rust.
    Acetone and ATF? Never tried it.

    I'm guessing that you are able to fill each cylinder full enough to submerge the rings fully.
    Try the solvent route and see how it goes.

    Read about the fill and burn method also, but that will require removing the engine to get the cylinders vertical.
    If you get that far you might just sink the engine in a barrel diesel fuel for a while.


    My KS601 ?

    Well the carbs are cleaned and reassembled, need some fiber washers, orings. Little stuff..
    Got to get more info about the floats and the needles that pass thru them to shut off the fuel.
    Dont think they should turn in place - may need to do a little soldering.

    Cylinders were blasted (outside only) and have a first coat of paint for protection.
    Bores got a quick 3 stone 180 hone just to cut the surface glaze and rust.

    Pistons are off the rods and I've been decoking them. Measured the bore and ring gaps, don't have any specs on proper gap or clearance specs just yet.
    75mm with .005 clearance and .020 gap so far... that has to be a little large on the gap using .004 to .005 per inch of bore as a standard.

    Peeking at the bigends and those kazillion (well, 30 each side) needle bearings , things seem real smooth and clean .
    I don't think I can tell for certain unless I drop the caps and I'm not comfortable yet with the approach.
    All those needles and the cages must stay in order during disassembly, just dumping them out thru the sump is not recomended. I dunno ...


    Don in Nipomo
  13. Quickv4

    Quickv4 Pro Turd Polisher

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    Try Acetone/ATF first, cheap to make and works just as good/better than kroil. Ive used both!

    Been enjoying this thread so far, Airhead threads are ok, but this guy- more oddball- moar betta
  14. bmwhacker

    bmwhacker Still on 3 wheels

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    What ratios of each?....50-50?
  15. Sniper X

    Sniper X De Oppresso Liber

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    I hear it is big with Granola Freaks too, and ToFoo nuts as well...
  16. Sniper X

    Sniper X De Oppresso Liber

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    why not just get a can of PB Blaster and shoot a bunch in each cylender? That stuff works better than anythig at loosing stuck metal parts.
  17. bmwhacker

    bmwhacker Still on 3 wheels

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    Never seen or found "PB Blaster"...what is it? A spray penetrating oil? I have the clylinders sealed up and am filling to the brim through the spark plug holes.
  18. disston

    disston ShadeTreeExpert

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    PB Blaster, it's the newest mass marketed rust buster. Works OK or just better than OK but the real deal is Kroil. Every time this subject comes up you will get 15 different expert opinions and no two of them will agree. I heard it was ATF and diesel fuel oil now it's acetone. Any one of these mixtures or products will probably work. I like Kroil. I was the first to suggest you use something other than Marval Mystery Oil and so now I insist all the Band Wagon jumpers get off my Band Wagon. It was my idea to use something other than Marval so the rest of them can take a hike.

    But probably use what ever you can find. The acetone should be available at a local hardware store.:freaky
  19. bmwhacker

    bmwhacker Still on 3 wheels

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    My past experience is limited to one moderately rusted engine. The Zundapp appears to be a little more stuck....visibly the BMW engine I previously freed up looked at lot worse than this Zundapp engine.
    I happened to have a couple gallons of the Marvel oil (found 6 gallons in an old 64 VW I bought a few years ago....along with a bunch of unspent 50 Cal and 20mm ammo.:eek1 ) so went with what I had on hand.
    I'll be looking for some Kroil on my next parts search expedition. Lots of gun shops out here in the wild west.:lol3
  20. disston

    disston ShadeTreeExpert

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    There is the problem of price with Kroil. In small cans it cost almost $10. Not sure how much it would cost by the gallon but I'm sure it ain't cheap. You might use a little bit of the Kroil mixed with the acetone/ATF. I only do stuff that uses small amounts therefore it would be the first thing I think of.