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05-14-2009, 07:32 AM
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#1 | |
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for a corrector life
Joined: Jun 2005
Location: New Yawk City (heavy Boston accent)
Oddometer: 13,152
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You decide how i fix my airhead this weekend!
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.
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05-14-2009, 07:47 AM
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#2 |
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G(/)S ... what else!
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I left the pistons in the bore, detached from the conrod, worked for me.
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Some of the above is fact, some is fiction, some is my personal imagination and some is just simple truth. [me] ... i'm not touring around the world, but neither are most of the guys i see running overloaded spam cans ... [bmwblake] Stephen Bottcher Ontario, Canada '72 R75/5 The Blues www.stephenbottcher.net |
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05-14-2009, 07:49 AM
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#3 |
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takin' a break, boss
Joined: Jul 2005
Location: Elmore, VT
Oddometer: 1,766
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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
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airhead aficionado |
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05-14-2009, 07:50 AM
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#4 |
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Beemerholics Anonymous
Joined: Jul 2002
Location: Jackson's Bottom Oregon
Oddometer: 7,392
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It all depends...
Don't you just love that answer?? 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.
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Wanted: Dead, smashed, crashed or trashed gauges BMW GAUGE REPAIRS - TACH*SPEEDO*CLOCK*VOLT METER *PODs & LIGHT BOARD* |
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05-14-2009, 09:11 AM
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#5 |
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n00b
Joined: Apr 2009
Oddometer: 7
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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.. |
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05-14-2009, 09:24 AM
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#6 | |
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airhead or nothing
Joined: Mar 2004
Location: Shoreline, WA
Oddometer: 7,976
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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.
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"punkrocks what it's all about" - J. Strummer Quote:
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05-14-2009, 09:42 AM
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#7 |
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Wisconsin Airhead
Joined: Nov 2004
Location: Madison WI
Oddometer: 3,451
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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.
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JT www.northwoodsairheads.com www.jefftrappwindsors.com "Between two explanations, choose the clearest; between two forms, the most elementary; between two expressions, the shortest." Between two motorcycles the simplest (DW) Eugeni d' Ors (1881-1954); Spanish writer. |
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05-14-2009, 09:45 AM
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#8 |
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Beastly Adventurer
Joined: Mar 2008
Location: Greater Chicago
Oddometer: 9,786
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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?
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05-14-2009, 09:23 AM
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#9 | |
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Don't buy from Brad
Joined: Aug 2005
Location: Savannah - the dirty south
Oddometer: 7,403
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Quote:
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On tap:Nada Aging: 3 experiments in mead - blackberry, apple, and straight honey |
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04-05-2010, 07:01 PM
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#10 | |
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Marinoni man
Joined: Aug 2008
Location: Saskatchewan
Oddometer: 1,858
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Quote:
I was planning on leaving the pistons on the rods as I could see no real reason for not doing it this way. Unless of course there is a lot of buildup. |
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04-06-2010, 11:10 AM
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#11 | |
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Beastly Adventurer
Joined: Aug 2002
Location: Loughborough, Leicestershire. England
Oddometer: 3,793
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Quote:
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