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Old 10-26-2012, 12:56 PM   #46
brocktoon
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Regarding the wheels: before and after what !?
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Old 10-26-2012, 01:28 PM   #47
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Coming along nicely...
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Old 10-26-2012, 02:14 PM   #48
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How did you get those fork bottoms clean? Painted, powder coated?
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Old 10-26-2012, 02:17 PM   #49
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Quote:
Regarding the wheels: before and after what !?
Cleaned rim, new spokes, painted hubs, and checked bearings

Quote:
How did you get those fork bottoms clean
Brass wire wheel, Al oxide blasted in a blast cabinet, hot soap and water, and paint.
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Old 10-26-2012, 07:46 PM   #50
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Originally Posted by Captain Yesterday View Post
So $300 isn't so bad "for California" good old Paso Robles DMV only a 10min wait and willing to actually help. Good thing I'm not in LA or the Bay Area I would rather eat glass than go to a DMV there.
Dude, tell me about it.
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Old 11-06-2012, 09:18 AM   #51
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Left side rod bearings



Right side rod bearings



Housing





Crank








Rear main



That engine sprocket did not want to come off.



What the hell is up with this myth that BMW's easy to work on yeah right Taking this engine apart was a total pain in the ass. You need a "special" tool for just about everything, and nothing came apart willingly.

Only question is on the right side rod bearing. It's not smooth enough to where I feel comfortable reinstalling it. So do I replace the the rod bearing and leave the crank alone or do I take the crank to a chop and have them grind it down to match the new road bearing? The crank feels fine to the touch.

The front main looks ok but the back is boarder line as well as the thrust washers bearings.

decision decisions do I replace all the bearings or just the rod bearing decision decisions I guess it's up to how much more money I want to dump into this thing.

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Old 11-06-2012, 10:08 AM   #52
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All your bearings seem to have some scoring. I would replace all of them. Never grind an airhead crank, they tend to break if its done. There are different theories why, but the rule is don't.
Just buy new standard big end bearings and leave the crank standard.
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Old 11-06-2012, 03:20 PM   #53
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All your bearings seem to have some scoring. I would replace all of them. Never grind an airhead crank, they tend to break if its done. There are different theories why, but the rule is don't.
Just buy new standard big end bearings and leave the crank standard.


Right hand rod shows signs of either dirty assembly or something got past the filter.

Buying standard bearings is great ... if the journals still measure out at stock spec's and the mains can be re-claimed by linishing ... and no oval'ing of the big end.

Cranks can be ground ... the trick is by who and whether they get the correct radius




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Old 11-06-2012, 03:36 PM   #54
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The crank big end bearings are not really expensive. I'm not going to look it up but I have seen a couple little pieces of rubber cost more. Not uncommon for there to be a little scoring. Check for grooves in the corresponding place of the crank. I have put car motors together with a little scoring in the crank but these were fleet vehicles. On an Airhead I might want to find a better crank if it looks bad. But I also would probably use a crank that had a couple small scratches.

I have mostly heard bad stories about regrinding Airhead cranks. Not only is the radius in the edges critical but the hardening of the metal is not easy to do. Some of the best say to get another crank. And here's the thing, any where in the World right now for any Airhead vintage engine needed an extra, spare, used crank can be found. They are cheap. Maybe in 50 years it will be a different story
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Old 11-06-2012, 03:45 PM   #55
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You say the journals are smooth to the touch. Does your fingernail catch in the grooves?

You've already gotten two opinions on whether or not crankshaft journals can be ground. Here's a third from Airhead guru Oak Okleshen:

Quote:
Regrinding cranks is OUT--No Go. After factory finishing grinding the
bearing journal surfaces are hard nitrided and is a very thin suface, anywhere
from 0.003 to 0.005 inches. Regrinding will destroy the nitriding and directly
underneath the substrate is relatively soft and won't hold up. So long
bearing surface. If you got a bum crank, overheated, or discolored or scuffed up
or non-uniformity of dimensional specs, don't waste your time on it except
to make a lamp out of it.
In short, you can grind it but it won't last long and you'll be back in the same position soon enough. Used cranks in good condition are not impossible to get ahold of through the usual Airhead parts folk.

Quote:
What the hell is up with this myth that BMW's easy to work on yeah right Taking this engine apart was a total pain in the ass. You need a "special" tool for just about everything, and nothing came apart willingly.
Is there another comparable bike you can think of that doesn't require special tools to pull apart to the bare crankcase? Not being sarcastic, I'd genuinely like to know. Did you pick up an engine disassembly kit from Cycleworks? It has pretty much everything you need to tear it apart just a few good grunts -- except the con-rod bolt removal tool, which is available from Napa.

brocktoon screwed with this post 11-06-2012 at 03:52 PM
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Old 11-06-2012, 03:55 PM   #56
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Originally Posted by brocktoon View Post



What other bikes don't require special tools to pull apart to the bare crankcase? Not being sarcastic, I'd genuinely like to know.


Seriously , an early K series 2 valve bm'.


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Old 11-06-2012, 04:07 PM   #57
FR700
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Originally Posted by brocktoon View Post
You've already gotten two opinions on whether or not crankshaft journals can be ground. Here's a third from Airhead guru Oak Okleshen:

In short, you can grind it but it won't last long and you'll be back in the same position soon enough. Used cranks in good condition are not impossible to get ahold of through the usual Airhead parts folk.


Nothing to stop you getting the crank re-nitrided , happens all the time. As I said , the trick is by who and if they understand ...

Am I talking out my ass ? ... a widdle pic'


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Old 11-06-2012, 04:07 PM   #58
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Huh. Wonder why Airheads got the "easy to work on" reputation while K series were overlooked?

What's re-nitriding run?
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Old 11-06-2012, 04:30 PM   #59
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What other bikes don't require special tools to pull apart to the bare crankcase? Not being sarcastic, I'd genuinely like to know.
Quote:
Is there another comparable bike you can think of that doesn't require special tools to pull apart to the bare crankcase? Not being sarcastic, I'd genuinely like to know. Did you pick up an engine disassembly kit from Cycleworks?
No I didn't pick up the kit, I've been borrowing the BMW specific tools, or making my own. I've gone through a couple of engines over the past couple of years couple of bmw car engines, air cooled porsche, toyota 4 cylinder truck, and a couple motocross 2 stroke engines. Motocross 2 stroke engines are so easy to completely dissemble and rebuild.

As for the crank, the only reason why I asked about re-grinding it to match the new bearings is that, that is what I have done in the past for other car engines. As for this crank it feels fine running my finger and nail along any part of the crank. The only areas that don't feel ok is one of the rod bearings and the thrust washer bearings on the back part of the main. The mains on both ends feel ok, but the back one looks questionable but feels ok. As for the rod bearing that needs to be replaced and the scoring is in a different location from where the journal is. So I'm fairly sure the crank is ok. The motor only has 58,xxx miles on it.

I think since I'm this far I'll just replace all the bearings, that way the bottom end will be good to go for a long long time hopefully.


Thanks for the input
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Old 11-06-2012, 06:54 PM   #60
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Originally Posted by FR700 View Post
a widdle pic'
Looks kinda like my Model A crank. What's the runout on the lathe?
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