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 11-26-2012, 11:13 AM   #16
Airhead Wrangler
Adios Mexico
 
Airhead Wrangler's Avatar
 
Joined: Mar 2008
Location: Back in Seattle, FINALLY
Oddometer: 6,355
Quote:
Originally Posted by robtg View Post
Why not do it right and send them to a machine shop, mill the top parallel to the bottom like they are supposed to be?
If they're really warped then yes that's the best way to go, but if it's just a nick, gouge, or other high spot on the mating surface, it's easily taken care of with a file or dressing stone.
__________________
R80ST Gets The HPN Treatment
Seattle to TDF on an airhead

Current rides: HPN #834, '93 R100GSPD "red rocket", '73 R75/5 Toaster mongrel, '80 Ducati Pantah 500SL, '92 DR350, '67 Honda SS50, '80 Honda Chaly.
Airhead Wrangler is offline   Reply With Quote
Old 11-26-2012, 01:47 PM   #17
Bluethumb OP
Gnarly Adventurer
 
Joined: Aug 2012
Location: Texas Hill Country
Oddometer: 124
I pulled the heads last night and will do just as suggested - take them to a buddy who is a machinist. He can disassemble the valves for me and fortunately he's really good at doing valve jobs.

The left head has a high point in the very center, near the center stud. In addition, placing a straightedge across the top and across the bottom, I can see gaps, noticeable, enough to slip a .0010 mm feeler gage here and there. The right head is similar but not as severe.

I'll find out more later this week when my buddy pulls the valves out. The valve faces look good from what I can tell, but of course he'll be able to measure the valve stems and guides.

In the end, it will be done right. And I guess in the end, that's all that matters!
Bluethumb is offline   Reply With Quote
Old 11-27-2012, 05:28 PM   #18
Stan_R80/7
Beastly Gnarly
 
Stan_R80/7's Avatar
 
Joined: May 2012
Location: VA
Oddometer: 1,146
I expect this is a typo: 0.0010 mm is a micron - which should have no problem sealing with a gasket. Similarly, a 0.001 inch gap (0.0254 mm) should seal OK with a gasket. Good luck!
Stan_R80/7 is offline   Reply With Quote
Old 11-28-2012, 05:37 AM   #19
Bluethumb OP
Gnarly Adventurer
 
Joined: Aug 2012
Location: Texas Hill Country
Oddometer: 124
You're absolutely correct, .10 mm gap.
Bluethumb is offline   Reply With Quote
Old 11-29-2012, 10:38 AM   #20
Crisis management
Latte riders FTW!
 
Crisis management's Avatar
 
Joined: Feb 2007
Location: New Zealand
Oddometer: 1,415
I'm obviously not alone in this..... The R80 gets it's valve covers pulled this weekend and a few high spots removed, I will be using the file or dressing stone method having found it very effective in the past. I have an indelible memory from my apprentice years of a demonstartion on draw filing a 6 cylinder cast iron head flat after it had warped, there's nothing a hand tool can't fix!
__________________
Orange...cause it makes me look like I know what I'm doing!
Crisis management is offline   Reply With Quote
Old 11-29-2012, 11:36 AM   #21
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,457
Quote:
Originally Posted by Crisis management View Post
I'm obviously not alone in this..... The R80 gets it's valve covers pulled this weekend and a few high spots removed, I will be using the file or dressing stone method having found it very effective in the past. I have an indelible memory from my apprentice years of a demonstartion on draw filing a 6 cylinder cast iron head flat after it had warped, there's nothing a hand tool can't fix!
Something I heard many years ago and would like to know more about. It was either mechanics or probably engineers in training in Germany, they had classes in filing. The spent hours each week learning various methods of using a file.

There are some small publications on the subject but I've not found much in depth.

I own some good files and I also have handles that fit. I've found a good handle improves the experience.
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is offline   Reply With Quote
Old 11-29-2012, 12:59 PM   #22
Stan_R80/7
Beastly Gnarly
 
Stan_R80/7's Avatar
 
Joined: May 2012
Location: VA
Oddometer: 1,146
My approach to getting the head surface in contact with the valve cover surface was based in the art of scraping. Although, no scraping of the valve covers was done - it was sanding using 180 grit paper. Scraping is a machinist technique to get two surfaces within extremely close contact to each other. Generally, one of the surfaces is part of a machine tool (lathe bed, mill bed, etc) and the other is a saddle or table. Marking fluid (typically prussian blue) is applied to one surface and where the blue is removed is where the metal is scraped (i.e. the high spots).

I reversed the process (since the head had raised spots) and instead removed material from where the blue was on the valve cover. After each sanding of the marked areas, the valve cover is completely cleaned, the blue reapplied to the head and the process repeated. Also, my fitting was done with the head on the bike - so sanding or filing on the head was prohibited due to getting debris in the engine.

Plenty of ways to skin a cat. Plus, as noted, it turns out my valve cover fit was not off that much and the eventual leak was found to be from a pushrod tube. The double gasket idea is not a bad one if it works to stop a valve cover leak (I had not thought of that). There is no reason for a high precision fit between the valve cover and head mating surfaces.
Stan_R80/7 is offline   Reply With Quote
Old 11-29-2012, 03:50 PM   #23
Crisis management
Latte riders FTW!
 
Crisis management's Avatar
 
Joined: Feb 2007
Location: New Zealand
Oddometer: 1,415
Quote:
Originally Posted by disston View Post
Something I heard many years ago and would like to know more about.
Draw filing is essentially holding the tip of the file on one hand, the handle in the other (as you normally would) but pulling on the tip rather than pushing on the handle to draw the file over the surface. Typically we push very hard on the handle which naturally rocks the file down onto the work piece, by relying on a controlled pulling action it is easier to guide with the handle and maintain a flat contact surface. Using engineers blue on the surface to show the high points as Stan mentions, allows the development of a flat surface.
I have no doubt that the surface is not truly flat but for low pressure situations (older engines / valve covers) it is sufficiently flat. Generally for something like the valve cover I will wet a sheet of 200 grit wet & dry paper, slap it on a nearby window (glass) and rub the mating surface directly on that. Glass is flat enough and the surface is done in a couple of minutes. Make sure you don't use old (50 years) glass as glass is actually a liquid at ambient temperature and flows downwards over the years resulting in a rippled surface.


Failing all this, two gaskets should work.....
__________________
Orange...cause it makes me look like I know what I'm doing!
Crisis management is offline   Reply With Quote
Old 11-30-2012, 07:01 PM   #24
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,288
I do not recommend those after market gaskets there or anywhere else. They are a problem waiting to happen IMO. Besides, the stock gaskets work perfect. I have only heard of the vavle covers being part of the trouble on the net. I have still never seen it. The soltion is milling your head. teh stop gap solution is two stock gaskets with sealant BETWEEN the gaskets. Otherwise, no need to use goop there or on any other paper gasket on our bikes.
supershaft is online now   Reply With Quote
Old 11-30-2012, 08:34 PM   #25
Bluethumb OP
Gnarly Adventurer
 
Joined: Aug 2012
Location: Texas Hill Country
Oddometer: 124
On both my '81 and '84 R80G/S's I used the Real silicon rubber gaskets, both valve overs and float bowls. Total milage, 70,000. Not one single problem. They worked great. Paper gaskets work fine for the valve covers, but the Real gaskets for the float bowls are far better.

The problem I'm having with this ST is because the previous owner over tightened the center stud pulling the surrounding surface up. My machinist is going to take a very light cut flattening the surface.

Once I get back to a nice, clean, flat surface on the mating surfaces, I'm going to use Real gaskets. Properly used, they work just fine.
Bluethumb is offline   Reply With Quote
Old 12-01-2012, 12:36 PM   #26
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,288
The cork bowl gaskets work perfectly for decades. How do you get better than that?

The heads warping is not from over torqueing the cover stud. It's from combustion heat.
supershaft is online now   Reply With Quote
Old 12-03-2012, 06:59 AM   #27
Uncle Pollo
happy cachiporra
 
Uncle Pollo's Avatar
 
Joined: Jun 2006
Location: Albuquerque, Neue Messico
Oddometer: 47,408
Quote:
Originally Posted by bmwhacker View Post
I ended up using two gaskets on each side on my R100s engine...no sealant. Don't like using sealant as valve cover removal seems to be a frequent event in my world. Maybe not a proper fix but they don't leak anymore.
This
Uncle Pollo 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 10:26 AM.


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