ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 05-14-2009, 07:32 AM   #1
BubbaZanetti OP
for a corrector life
 
BubbaZanetti's Avatar
 
Joined: Jun 2005
Location: Conakry, Guinea
Oddometer: 13,156
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.
__________________
Quote:
Originally Posted by OleGrumpy
Real, red blooded Americans hate taxes.
BubbaZanetti is offline   Reply With Quote
Old 05-14-2009, 07:47 AM   #2
StephenB
G(/)S ... what else!
 
StephenB's Avatar
 
Joined: Aug 2005
Location: Ontario
Oddometer: 2,046
I left the pistons in the bore, detached from the conrod, worked for me.
__________________

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
StephenB is offline   Reply With Quote
Old 05-14-2009, 07:49 AM   #3
elmoreman
takin' a break, boss
 
elmoreman's Avatar
 
Joined: Jul 2005
Location: Elmore, VT
Oddometer: 1,773
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
__________________
airhead aficionado
elmoreman is offline   Reply With Quote
Old 05-14-2009, 07:50 AM   #4
Wirespokes
Beemerholics Anonymous
 
Wirespokes's Avatar
 
Joined: Jul 2002
Location: Jackson's Bottom Oregon
Oddometer: 7,795
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.
__________________
Wanted: Dead, smashed, crashed or trashed gauges
BMW GAUGE REPAIRS - TACH*SPEEDO*CLOCK*VOLT METER *PODs & LIGHT BOARD*
Wirespokes is offline   Reply With Quote
Old 05-14-2009, 09:11 AM   #5
jhallm5
n00b
 
Joined: Apr 2009
Oddometer: 7
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..
jhallm5 is offline   Reply With Quote
Old 05-14-2009, 09:23 AM   #6
datchew
Don't buy from Brad
 
datchew's Avatar
 
Joined: Aug 2005
Location: Savannah - the dirty south
Oddometer: 7,408
Quote:
Originally Posted by Wirespokes
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.
+1 . Both are easy. Getting the piston back in is not hard at all.
datchew is offline   Reply With Quote
Old 05-14-2009, 09:24 AM   #7
SOLO LOBO
airhead or nothing
 
SOLO LOBO's Avatar
 
Joined: Mar 2004
Location: Shoreline, WA
Oddometer: 8,545
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.
__________________
"punkrocks what it's all about" - J. Strummer



Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
SOLO LOBO is offline   Reply With Quote
Old 05-14-2009, 09:42 AM   #8
jtwind
Wisconsin Airhead
 
jtwind's Avatar
 
Joined: Nov 2004
Location: Madison WI
Oddometer: 3,498
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.
__________________
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.


jtwind is online now   Reply With Quote
Old 05-14-2009, 09:45 AM   #9
P B G
Beastly Adventurer
 
Joined: Mar 2008
Location: Greater Chicago
Oddometer: 9,995
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?
P B G is offline   Reply With Quote
Old 05-14-2009, 10:05 AM   #10
Rob Farmer
Beastly Adventurer
 
Rob Farmer's Avatar
 
Joined: Aug 2002
Location: Loughborough, Leicestershire. England
Oddometer: 5,038
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.



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.

Rob Farmer is offline   Reply With Quote
Old 05-14-2009, 10:38 AM   #11
CurlyMike
Formerly SaddleSoar
 
CurlyMike's Avatar
 
Joined: Feb 2008
Location: east of Dallas
Oddometer: 978
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...
__________________
Giving the horses and the wife a break from riding...
CurlyMike is offline   Reply With Quote
Old 05-14-2009, 10:45 AM   #12
crazydrummerdude
Wacky Bongo Boy
 
crazydrummerdude's Avatar
 
Joined: Nov 2006
Location: St Louis, MO
Oddometer: 7,498
Man, disconnecting the piston from the connecting rod seems like too much of a bitch..

Here's how I've done it.



__________________

crazydrummerdude is offline   Reply With Quote
Old 05-14-2009, 10:47 AM   #13
crazydrummerdude
Wacky Bongo Boy
 
crazydrummerdude's Avatar
 
Joined: Nov 2006
Location: St Louis, MO
Oddometer: 7,498
Quote:
Originally Posted by Rob Farmer
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.
On some of my bikes, the circlips are magical. One second they're there, and you're fiddling with them. The next... POOF! Gone. Gotta wear safety glasses.

My BW80 was a good example. Both disappeared far off into the blue yonder.
__________________

crazydrummerdude is offline   Reply With Quote
Old 05-14-2009, 10:49 AM   #14
Rob Farmer
Beastly Adventurer
 
Rob Farmer's Avatar
 
Joined: Aug 2002
Location: Loughborough, Leicestershire. England
Oddometer: 5,038
You need to take the barrels off to fit new O rings.

Is that a decompression plate under your barrel?
Rob Farmer is offline   Reply With Quote
Old 05-14-2009, 10:50 AM   #15
Rob Farmer
Beastly Adventurer
 
Rob Farmer's Avatar
 
Joined: Aug 2002
Location: Loughborough, Leicestershire. England
Oddometer: 5,038
Quote:
Originally Posted by crazydrummerdude
On some of my bikes, the circlips are magical. One second they're there, and you're fiddling with them. The next... POOF! Gone. Gotta wear safety glasses.

My BW80 was a good example. Both disappeared far off into the blue yonder.
I Know what you mean
Rob Farmer is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 11:30 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014