You decide how i fix my airhead this weekend!

Discussion in 'Airheads' started by BubbaZanetti, May 14, 2009.

  1. BubbaZanetti

    BubbaZanetti for a corrector life

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    Ok, doing the push rod tube seals.

    for those of you who've done this job (it's on an 84 R80ST) which would you recommend:

    leave the piston attached to the con rod, pull the cylinder off


    leave the piston in the bore and detach from the con rod


    i've got new circlips just in case option 2 wins out. thanks everyone.:thumb
    #1
  2. StephenB

    StephenB G(/)S ... what else!

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    I left the pistons in the bore, detached from the conrod, worked for me.
    #2
  3. elmoreman

    elmoreman takin' a break, boss

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    last time I took the pistons out, next time I leave the pistons in and detach from the con rod.

    But I'll wait to see what Anton says:D
    #3
  4. Wirespokes

    Wirespokes Beemerholics Anonymous

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    It all depends...

    Don't you just love that answer?? :lol3

    Have you been in there before? Is the piston carboned up?

    Frankly, it's really easy to leave the piston attached to the rod (if no piston cleaning is needed) to do the job, and to slide the piston back into the cylinder. I use my thumb nails to gradually work the rings back into the cylinder one at a time and it goes quickly - like a few minutes.

    Clean everything up really well before taking apart to help prevent grunge entering the crankcase, but once apart, you'll want to clean some more - guaranteed!

    So I'd say it all depends on the carbon build up. I prefer to remove all carbon and polish the piston tops and compression chamber and remove any sharp edges protruding into it - like around the spark plug and the edges of the valves. Carbon and sharp edges radiate energy and promote pinging. You'll notice the difference once this has been done.

    And ensure the ring gaps are separated 120 degrees. I like having the oil ring with the gap up, which leaves the other two forward and back. It makes the most sense to me to have the compression ring gap towards the intake rather than towards the heat of the exhaust.
    #4
  5. jhallm5

    jhallm5 n00b

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    I just did this job last weekend. It was Very easy and worth the Time.
    I had to take the Pistons off the rods and out of the Cyl, to clean the carbon. I did put the piston back in the bore on the bench and then
    put in the pin and clip back in the rod. It was much easier then getting
    the rings back in the Bore on the Bike. Cleaning the carbon made a big
    difference in idle and spark knock.. Good Luck..
    #5
  6. datchew

    datchew Don't buy from Brad

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    +1 . Both are easy. Getting the piston back in is not hard at all.
    #6
  7. Solo Lobo

    Solo Lobo airhead or nothing

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    One note here, make sure to replace the piston pin circlip you remove with a new one... some will tell you this isn't necessary but just check stagehand's thread and see why "cheap insurance" is sometimes justified.
    #7
  8. jtwind

    jtwind Wisconsin Airhead

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    I've done it both ways. Now with early bikes and the wire spring clip I leave the piston pin alone and take the cylinder off and leave the piston. I have a adjustable piston ring clompressor that works very well and it"s easy to reinsert the piston. Frankly with the steps at the bottom of the cylinder it's not that hard to do with your fingernails.
    #8
  9. P B G

    P B G Long timer

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    Just from curiosity, what's the fit on the wrist pin? Is there interference with either the rod or piston or is it floating on both faces?
    #9
  10. Rob Farmer

    Rob Farmer Long timer

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    Piston out every time for me. Fiddling about between the engine studs is too much of a pain in the arse. I leave the wrist pin poking through slightly, theres enough clearance for you to feel it line up on the rod.

    [​IMG]

    Just don't forget to block the crankcase with rags or towels. I lost a circlip into the crancase a few years ago. Taking the sump off and fishing about in the goo isn't pleasant.

    [​IMG]
    #10
  11. CurlyMike

    CurlyMike Formerly SaddleSoar

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    Now this is what I am talking about. We need more posts and replies like this one. Have two bikes I need to do and you all have inspired me. I personally would like to see more repair/maintenance threads like this one. Picts are a huge plus. Thanks for all those who have shared...
    #11
  12. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Man, disconnecting the piston from the connecting rod seems like too much of a bitch..

    Here's how I've done it.

    [​IMG]

    [​IMG]
    #12
  13. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    On some of my bikes, the circlips are magical. One second they're there, and you're fiddling with them. The next... POOF! Gone. :lol3 Gotta wear safety glasses.

    My BW80 was a good example. Both disappeared far off into the blue yonder.
    #13
  14. Rob Farmer

    Rob Farmer Long timer

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    You need to take the barrels off to fit new O rings.

    Is that a decompression plate under your barrel?
    #14
  15. Rob Farmer

    Rob Farmer Long timer

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    I Know what you mean :lol3
    #15
  16. P B G

    P B G Long timer

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    Last time one popped loose on me I was disassembling GMC 248 pistons on my work bench, Looked everywhere, finally round it 3 days later when I did my laundry, went in my shirt pocket.
    #16
  17. BubbaZanetti

    BubbaZanetti for a corrector life

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    yeah, i gotta replace an o-ring that you don't have to worry about.


    decarbonizing the head/piston? if i go this route, what kinda cleaner is recommended. my bike only has 17K on it and the oil is damn clean after 500 miles and there no smoking or anything under hard acceleration. not sure it's a huge need at this point.
    #17
  18. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Ah, all you said was push rod tube seals. I forgot about those o-rings.

    :doh
    #18
  19. danedg

    danedg Horizontally Opposed

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    You'll just create a big mess of gooky shit that you can clean out again sometime not so soon....
    Try runnin' it a tad leaner... it'll burn off! But not TOO lean...it'll burn up!
    #19
  20. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    :lol3

    While disassembling one of our new-to-us antique engines, we needed 4 hands to remove a valve spring keeper. I got it off while my brother compressed the spring. In the blink of an eye, the valve spring shot against my arm, the keeper bounced off, landed on my brothers shoulder, and the spring landed on another project. I've got a pic of the spring/keeeper grease print it left on my arm. I'll post it when I find it.
    #20