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 01-04-2011, 09:43 AM   #61
jimbee OP
Airhead Intermediate
 
jimbee's Avatar
 
Joined: Nov 2008
Location: Vancouver BC / Reno NV
Oddometer: 334
Quote:
Originally Posted by anonny View Post
Did you push the ring into the bore with a piston to keep it 90 degrees to the cylinder?
Yes I did use the piston to keep it at 90 degrees, but still ended up with the large end gaps (0.55mm) (spec is 0.3 - 0.5mm) - even with the new rings? This reading was consistent between cylinders and at all points up and down within the cylinders. Any ideas? Should I just live with the larger gap?

Max and Bill - you're making me scared! Given the condition of the big end shells and the cylinders, it looks like it never seized - is that a clue that it didn't get THAT hot?

Also, as the rocker arm and push rod assemblies got very loose, perhaps the motor died because of irregular valve action before the engine was able to get hot enough to cause the aluminum to go soft!? Yes, I know, I should go to a machine shop and have them measure everything, I'm just starting to have enough of this teardown and want to put it back together!!
__________________
R100GS for going far, FZ1 for going fast, TE250 for getting dirty, and DR650 for when one of the others needs work
jimbee is offline   Reply With Quote
Old 01-04-2011, 12:04 PM   #62
Wirespokes
Beemerholics Anonymous
 
Wirespokes's Avatar
 
Joined: Jul 2002
Location: Jackson's Bottom Oregon
Oddometer: 7,828
I've heard stories about BMW's specs and what tolerances they actually build to. If it was running fine with those gaps before, I'd probably leave it. It's way too easy to tear into if it proves a problem later on.

I'm getting the idea the bike died because of the rocker assemblies being loose and floppy, as well as running on choke. And it's quite possible it didn't run as long as your brother said - did he actually watch the clock or was he guessing?

Still, this is a testament to the ruggedness of these bikes.
__________________
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 01-04-2011, 01:16 PM   #63
pennswoodsed
lizards,bugs and me
 
pennswoodsed's Avatar
 
Joined: Jan 2007
Location: Reading,Pa
Oddometer: 675
New definition of Toaster !

I am not an air cooled guy,but those gaps seem really big to me .
Regards,Ed


Ps your brother's most embarrassing secret and picture should be posted wherever it would do the most good.
pennswoodsed is offline   Reply With Quote
Old 01-04-2011, 01:27 PM   #64
bereahorn
Beastly Adventurer
 
Joined: Mar 2002
Location: North Coast (Lake Erie)
Oddometer: 1,059
bereahorn is offline   Reply With Quote
Old 01-04-2011, 05:18 PM   #65
datchew
Don't buy from Brad
 
datchew's Avatar
 
Joined: Aug 2005
Location: Savannah - the dirty south
Oddometer: 7,408


More pics please. Don't take this the wrong way, but I'm enjoying learning from what these potentially toasted parts look like.
datchew is offline   Reply With Quote
Old 01-04-2011, 10:51 PM   #66
jimbee OP
Airhead Intermediate
 
jimbee's Avatar
 
Joined: Nov 2008
Location: Vancouver BC / Reno NV
Oddometer: 334
Quote:
Originally Posted by datchew View Post


More pics please. Don't take this the wrong way, but I'm enjoying learning from what these potentially toasted parts look like.
Happy to post pics datchew, and especially happy to add something that could help others (I've been fortunate to take much from adv over the last couple years), but not sure what else to show you. Everything seems to look fairly normal to my non-expert eyes. I'm still waiting for a second set of new big end shells, then I think I'm going to slap it all back together unless someone tells me that I must go get the cylinders honed (but I don't think it seized and its only a travel tractor for me, not a high performance speed deamon).

It anyone wants to see any part in particular let me know...
__________________
R100GS for going far, FZ1 for going fast, TE250 for getting dirty, and DR650 for when one of the others needs work
jimbee is offline   Reply With Quote
Old 01-04-2011, 11:08 PM   #67
Beemerguru
Beemerguru...G/S guy
 
Beemerguru's Avatar
 
Joined: Nov 2006
Location: Foster City, CA
Oddometer: 877
It might be worth it to try another set of rings. I had a new BMW set last summer that measured too big right out of the box. Swapped for another set and they were dead on.

I'm with Robert that the plastic messed up the valve train and caused the shut down since there doesn't see, to be any evidence of the piston seizing. And if the bike ran longer than 2-3 minutes with the choke on, something else in the original setup was way out of whack too.
__________________
Greg Hutchinson
BMW Club of Northern California, Ambassador, BMW MOA, Vice President Vintage BMW Club
http://gregsgssite.shutterfly.com/
Beemerguru is offline   Reply With Quote
Old 01-04-2011, 11:09 PM   #68
fishkens
Further...
 
Joined: Nov 2009
Location: Seattle, WA
Oddometer: 5,147
Quote:
Originally Posted by jimbee View Post
I'm still waiting for a second set of new big end shells, then I think I'm going to slap it all back together
Don't forget the assembly lube and to crank the engine w/out plugs to get oil circulating before firing it up on reassembly.

Just thought I'd mention it.
__________________
Forging ahead, down a false trail.
fishkens is offline   Reply With Quote
Old 01-05-2011, 05:12 PM   #69
JZed
Adventurer
 
Joined: Mar 2010
Location: Nw South Carolina
Oddometer: 41
Don't suck the studs out of your GS

Jimbee

Seems I remember you mentioned that one cylinder stud that was loose and someone mentioned using a hand tap to chase the threads. Which stud is loose? Upper front?
Go carefully there. You might ask Shail sp?? about that. And by all means, if you don't have one get a good calibrated torque wrench for your assembly process. Keep the torque value on the heads to 25 ft lbs max. The BMW spec is 25 +/- 2 ft lbs, but the damn studs will start to "suck" out over time if you go over 25 ft lbs. This is especially a problem on the later blocks. Lots of good information on Snowbum's page.

http://bmwmotorcycletech.info/techindex.htm

Its a little hard to read, but it is really a good resource, and has kept me out of trouble by providing a cross reference for my Cylmer Manual.

Ride Safe
JZed is offline   Reply With Quote
Old 01-05-2011, 05:24 PM   #70
Wirespokes
Beemerholics Anonymous
 
Wirespokes's Avatar
 
Joined: Jul 2002
Location: Jackson's Bottom Oregon
Oddometer: 7,828
It's been mentioned before that torquing lubricated bolts requires a lower value by about 25%. So unless you've cleaned the studs and nuts of all oil film, reduce the torque to 18 or 19 foot pounds.

If the head stud still threads into the block, but loosely, try the permanent loctite (red). But be careful if it's a top stud since there's an oil galley from each one of them that sends lube along the stud to the rocker assembly.
__________________
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 01-05-2011, 05:30 PM   #71
concours
WFO for 41 years
 
concours's Avatar
 
Joined: Dec 2008
Location: Kensington, NH USA
Oddometer: 5,145
Quote:
Originally Posted by Ben Carufel View Post
Start by kicking your brother's ass.
+1... and when you're done, do it again. Get about $2,000 cash from him to START into the repair.
__________________
Too much is just barely enough.....
concours is offline   Reply With Quote
Old 01-10-2011, 06:48 PM   #72
jimbee OP
Airhead Intermediate
 
jimbee's Avatar
 
Joined: Nov 2008
Location: Vancouver BC / Reno NV
Oddometer: 334
Quote:
Originally Posted by Beemerguru View Post
It might be worth it to try another set of rings. I had a new BMW set last summer that measured too big right out of the box. Swapped for another set and they were dead on.

I'm with Robert that the plastic messed up the valve train and caused the shut down since there doesn't see, to be any evidence of the piston seizing. And if the bike ran longer than 2-3 minutes with the choke on, something else in the original setup was way out of whack too.
Good idea Beemerguru. I'm going to take a full set of cyclinder, rings, and a piston down to the shop and see if we can't find a couple sets of rings that will actually be within spec!

As for the original set up, right or wrong, this is how the bike used to start:

- Cold, the bike would only start with full choke
- After about 45 seconds, I would reduce choke to half otherwise the engine would die
- After 3 to 4 minutes on half choke, the idle would begin to rise slowly up to about 4,000 rpm where it would then stay until I turned off the choke.

Is this different than normal?

Quote:
Originally Posted by fishkens View Post
Don't forget the assembly lube and to crank the engine w/out plugs to get oil circulating before firing it up on reassembly.

Just thought I'd mention it.
Does good quality fresh oil count as assembly lube, or do I need something else?

Quote:
Originally Posted by JZed View Post
Jimbee

Seems I remember you mentioned that one cylinder stud that was loose and someone mentioned using a hand tap to chase the threads. Which stud is loose? Upper front?
Go carefully there. You might ask Shail sp?? about that. And by all means, if you don't have one get a good calibrated torque wrench for your assembly process. Keep the torque value on the heads to 25 ft lbs max. The BMW spec is 25 +/- 2 ft lbs, but the damn studs will start to "suck" out over time if you go over 25 ft lbs. This is especially a problem on the later blocks. Lots of good information on Snowbum's page.

http://bmwmotorcycletech.info/techindex.htm

Its a little hard to read, but it is really a good resource, and has kept me out of trouble by providing a cross reference for my Cylmer Manual.

Ride Safe
Yes, Snowbum's site sure is a wealth of info - I often perch the laptop on the bench and refer to him as I work. Between Snowbum, Haynes, Cylmer, and the pdf of the factory shop manual, they've basically formed my motorcycle mechanics course!

Yes, the loose stud is an upper front. I have heard many mixed messages on whether or not to locktite it!? I don't believe the threads in the case have been stripped, but I don't have a tap in the pile of tools I presently have at hand (I do have torque wreches though). Wearing gloves and using firm hand pressure, I can thread the stud in as deep as the others with out any tools. Just don't want it to back itself out over time.... Is there a consensus about whether or not to use locktite on these studs? (I understand to be very careful not to plug the oil passage that flows out into the stud cavity.)

Quote:
Originally Posted by Wirespokes View Post
It's been mentioned before that torquing lubricated bolts requires a lower value by about 25%. So unless you've cleaned the studs and nuts of all oil film, reduce the torque to 18 or 19 foot pounds.

If the head stud still threads into the block, but loosely, try the permanent loctite (red). But be careful if it's a top stud since there's an oil galley from each one of them that sends lube along the stud to the rocker assembly.
Well, another vote for careful use of locktite. Wirespokes, you seem to be right often....

Thank you for reminding me to lower the torque values on oiled threads - I never remeber this.

Still waiting for the plastic washers for the rockers so not much happending here.

Hope everyone is well! JB
__________________
R100GS for going far, FZ1 for going fast, TE250 for getting dirty, and DR650 for when one of the others needs work
jimbee is offline   Reply With Quote
Old 01-10-2011, 07:29 PM   #73
AlpinaE24
Gnarly Adventurer
 
AlpinaE24's Avatar
 
Joined: Nov 2010
Location: North Phoenix
Oddometer: 498
Quote:
Originally Posted by Ben Carufel View Post
Start by kicking your brother's ass.
Solid advice
__________________
1982 V45 Magna - The pavement ends?
1985 XL600R - the old model
1994 XR650L - Sold
2000 XR650R - Plated - Sold
2000 XR600R - Sold
AlpinaE24 is offline   Reply With Quote
Old 01-10-2011, 07:46 PM   #74
Wirespokes
Beemerholics Anonymous
 
Wirespokes's Avatar
 
Joined: Jul 2002
Location: Jackson's Bottom Oregon
Oddometer: 7,828
Your choices on the stud are time-sert or loctite. I get the idea the threads are still there, just a little loose. Since it's not that difficult getting in there (in case the stud comes loose again), I'd just loctite the thing. That permanent red loctite is pretty rugged stuff and I'd think it would hold. Make sure the hole and stud are really really clean. And don't apply any loctite to the stud (since that would force it into the oil galley), only in the hole beyond the oil exit hole (about a 1/4" from the surface).

Let it set up for several hours or over-night. Then once it's all back together, leave the valve cover off at start-up and watch for oil flow from that rocker. It may be possible to rotate the engine with the top end off and generate enough flow to check that it's not plugged. But I've never tried it that way. Be careful the rod doesn't damage the case.
__________________
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 01-26-2011, 03:37 PM   #75
jimbee OP
Airhead Intermediate
 
jimbee's Avatar
 
Joined: Nov 2008
Location: Vancouver BC / Reno NV
Oddometer: 334
Oy

FInally had time to drop by Shail's again today and brought the cylinders, pistons, and rings in with me. I'm still trying to figure out why the ring gaps are so big even with new rings? Shail scratched his head too. He put one of the pistons in the cylinder without any rings and there was lots of side to side freeplay - much more than he says in normal, so he figures that the cylinders are toast.

But it doesn't make total sense to my little brain...

The ring gap is the same, albeit greater than spec, from the top of the cylinder to the bottom, so it is not like there is any measurable wear from the piston and rings.

Perhaps Max is on to something about the metal doing wierd things when it got so hot, but doesn't it seem wierd that the nikasil cylinders expanded evenly top to bottom and excatly the same on both sides? I mean if they were warped or defmormed then it would be more obvious - the fact that everything is consistant and uniform makes me think there might be something else going on?

What am I missing?

Quote:
Originally Posted by Max Headroom View Post
I'm still concerned about your engine parts.

A visual inspection is useful, but I'd like to see a machinist pass a cylindrical dial guage over the barrels, and a hardness test performed on the heads. Due to the abnormally high heat your engine was subjected to, the big enemy is distortion so it's possible for your barrels to no longer be round, and for the heads to have gone soft. If the heads are soft, the valve guides could move and/or the valve seats could drop out.

When alloy gets overheated, weird stuff can happen.
__________________
R100GS for going far, FZ1 for going fast, TE250 for getting dirty, and DR650 for when one of the others needs work
jimbee 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 02:08 AM.


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