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Cub engine queston?

Post in 'The Gear' started by smokinj, Jul 22, 2013.

  1. charly

    charly Guest

    I would say that would work fine.. You could put a steel rule on edge and see just how flat it is..Check a few spots with a feeler gauge underneath, .001 doesn't go in your good...or even get down and see if you can see light underneath the straight edge, shine a flash light behind it... Another thing I use as a sealer that never hardens is Hylomar.. works great. It was developed for Rolls Royce to use on their jet turbines to seal up any oil leaks when they started using synthetic oil.. I used it at Harley... A one shot deal.. They make a spray too.. You can coat stuff and put it together a week later... Some people over apply sealer,, if you do with hylomar, fear not, it will not plug any oil passages inside a motor... We saw a few lower end crank pin oil galleys plug with regular RTV silicone which took the lower ends out from lack of oil.. Someone had applied too much silicone on a cam cover.. Hylomar great stuff, not cheap but easy to take back apart and clean up and no oil leaks... I use to dip 1/4-20 allen screws into the end of the tube and coat the screws that had oil sitting behind them on a primary cover etc... Good stuff.
    smokinj likes this.

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  2. charly

    charly Guest

    Sweet! That's what they had at the Harley Factory School in the Engine building class..
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  3. charly

    charly Guest

    Soap and water that head when your done.. You want no grit getting into your cylinder.. Found out after boring cylinders and final honing them that brake clean never got the fine stone dust and slurry out of the pores of a cylinder,,, Hot soap and water and a soft brush did... otherwise just brake clean left residue which ruined your new rings and piston once things got running and heated up.. Out came the junk from the pores.. Old timer that worked at the dealership told me how he once bead blasted a Harley case inside, never knew to use soap and water at the time, just used something like brake clean at the time and air... Bike went out after a complete motor rebuild,,, 2 days later it was back as a noisy smoking mess.. Glass beads had worked out of the pores once the motor got hot and circulated throughout the whole engine, ruining bearings etc.. The old timer said he refused to ever bead blast an interior of a case after that... So clean , clean , clean...;)
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  4. Joful

    Joful Minister of Fire

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    Good point. I forgot to mention that step. Anything I lap with paper goes under the faucet in the sink for a thorough cleaning before use!
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  5. Jags

    Jags Moderate Moderator Staff Member

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    One other little trick is to use a Sharpie marker on the gasket surface. As you run the head around the sandpaper you will easily notice where it is/isn't hitting the surface. Reapply as needed until flat as glass.
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  6. charly

    charly Guest

    Good idea . I use to use the sharpie to check the seat area on the face of valves after doing a 3 angle valve seat cut.. or bluing..
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  7. charly

    charly Guest

    Just got thinking,, sharpie the known low area on the head, once you start removing that, you'll know your getting close to getting her flat... Nice to see that everyone here cared to get you back up and running! Hearth rocks! :cool: And it wasn't cobber job ;) Hand fit like the good old days!
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  8. smokinj

    smokinj Minister of Fire

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    Would you set the head on the drill press with the granite on the table? Just a little spin a friend throw at me.
  9. Joful

    Joful Minister of Fire

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    No, I would not do that, if I'm reading you right. You want control over this, and you want random orbit, not spinning. Besides, how you gonna find the center point, and get the thing squared up nice on a drill press?

    Doing this by hand with SiC paper, it's a pretty quick job. You'll be at it only a few minutes.
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  10. smokinj

    smokinj Minister of Fire

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    So lick and stick sand paper to the granite and spin with a cordless drilll?
  11. MasterMech

    MasterMech Guest

    Run the head over the paper by hand. No power required.
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  12. charly

    charly Guest

    Should have never posted that video,,, sorry.. Hand is the way to go.. Mark the low spot by rubbing magic marker in that area,,, when you see the marker starting to get removed, you know your getting close to flat.. Keep wiping the head and checking..
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  13. Joful

    Joful Minister of Fire

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    Yeah... no drill (or any power tools) required! Also, you don't spin the head. Just work it in a random pattern around the paper. Not a bad idea to turn it 90 degrees every coupl'a strokes, but that's about it.
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  14. smokinj

    smokinj Minister of Fire

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    Granite. Slab clean. I have 3 pieces of sand paper. (That has no Velcro backing) 120. 180. 220. Is that going to be fine enough?
  15. charly

    charly Guest

    I would think the 220 should be fine... See how fast it removes material,,, you can always go coarser and then come back to a fine finish..
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  16. smokinj

    smokinj Minister of Fire

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    I just finish 120 grit all sharpie ink is gone. Going to go a little more with it and change to 180 grit.
  17. Joful

    Joful Minister of Fire

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    Cool. For future reference, start finer than you think you need. When it inevitably cuts too slow, go a step coarser. That way, you avoid starting too coarse and removing more material than necessary.

    Of course, more material removed = very marginally higher compression, so... no harm, no foul. ::-)
  18. smokinj

    smokinj Minister of Fire

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    I am super flat now with the 120. I can tell every bit is shinning. You cant put a piece of paper under anywhere. Would you keep going a jump up to 180 grit?
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  19. Joful

    Joful Minister of Fire

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    If the scratches are fine enough that you see them as being liquid tight, then you're good. I'd be surprised if you're there at 120 grit, but without seeing it up close...

    I would think you'd want AT LEAST 220 grit, and in fact would jump directly from 120 to 220. If you have 240 instead of 220, then I'd do 180 before 240. But again... not there to see what it looks like!

    BTW... what are you using for a head gasket? I always just used the OEM style.

    edit: Googling this, I find recommendations for everything from 120 to 800 grit, as the final surface. I guess opinions vary!
  20. smokinj

    smokinj Minister of Fire

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    Brand new kolher. I am not able to get a piece of paper under anywhere on it fresh cut all the way across. But I will jump to the 180.
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  21. Joful

    Joful Minister of Fire

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    You're probably fine either way, I guess. I tend to go OCD nuts on things like this. I guess I've got some Dexter blood in me.

    More important than the grit is flatness, and you've got that. More important than flatness is cleanliness, so wash the hell out of it under the faucet when you're done!

    Do note the spark plug thread is a steel insert. So, you'll want to be sure that's dry and oiled, after washing. The rest is just aluminum.
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  22. smokinj

    smokinj Minister of Fire

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    I have an Allen plug in there. With the 180 grit I now need a little sope just to keep it slippery enough. I AM GOING TO FINISH AT LEAST 220 GRIT
  23. charly

    charly Guest

    Hope you have an inch pound or foot pound torque wrench and take the time to use the proper torque pattern for the head... also try to bring the head up to its final torque in 3 gradually higher torque settings, doing all the bolts and moving the torque wrench up to a higher setting each time.. You should have a trouble free head gasket then.
  24. smokinj

    smokinj Minister of Fire

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    I do and the the granite was certified last in 1992. It was a last present to my uncle. Its never been touch since. I going. To run it up to 220 grit. Sandpaper is from my cater non Velcro. I Canto up to 1500 grit. Question is where is good enough?
  25. Joful

    Joful Minister of Fire

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    I think I went to 400, but others online quote anywhere between 120 - 600. I'd guess 220 is fine, but maybe wait for MasterMech to come in.

    The torque pattern is critical on these, and there are two different K301 torque patterns. Google (or the folks at onlycubcadets) is your friend, here. I gave my Kohler manual to the guy who bought my cub, so I don't have it anymore.

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