ADVrider

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

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-27-2013, 05:42 PM   #1
Quickv4 OP
Pro Turd Polisher
 
Quickv4's Avatar
 
Joined: Jul 2009
Location: Dickinson, Nort' Dakohtah- Orig. from Wiscowsin
Oddometer: 549
Question Polishing crankshafts and con rod bearing wear

Prepping the crank on my 1970 Guzzi Ambo. Original bearings were scored. Had original chrome bores. You can see the really bad bearing on the left, and its corresponding jounal on the same side. You can see the slight discoloration.

My fingernail does not catch on the journal at any point, and feels rather smooth.

My main question is what should I use to polish the discoloration out and make ot superdooper smooth while removing very little material, since I will be putting STD bearings back in. 800-1000 grit sandpaper? Scotchbrite??? Simichrome and a rag?



__________________
Jerry
____________________________
Great forum and Resource for 1st and 2nd gen Honda V4s SabMagIntercept


www.v4hondabbs.com
Quickv4 is offline   Reply With Quote
Old 09-28-2013, 06:50 AM   #2
vtwin
Air cooled runnin' mon
 
vtwin's Avatar
 
Joined: Jan 2005
Location: NorCal
Oddometer: 7,001
Send it out to a machinist/crank builder to polish.
__________________
"Alles hat ein Ende--nur die Wurst, sie hat zwei"
Monroe.

"You only have too much fuel if you're on fire"
unknown
vtwin is offline   Reply With Quote
Old 09-28-2013, 06:55 AM   #3
anotherguy
Beastly Adventurer
 
anotherguy's Avatar
 
Joined: Jun 2009
Location: the hills
Oddometer: 5,908
Having the crank polished is good. From the photos you posted it seems the oiling holes need chamfering as well. Chamfering aids the hydrodynamic wedge of oil that is the life of a plain bearing. I'd have the rods checked for ovality and correct it if needed. The hammering from bad bearings is hard on rods. I know this isn't what you wanted to hear but how often do you want to do this?

If it were mine I'd have the crank balanced,magnafluxed,polished and nitrided and rods done. Probably be under $300 for the crank. Rods are maybe $75 for the pair.

If you don't understand why just blindly assembling the crank w/new standard parts is a bad idea this might help.


This is a properly chamfered journal.
__________________
A lie has no feet......it can't stand alone.............
Jason Newsted
anotherguy is offline   Reply With Quote
Old 09-28-2013, 08:00 AM   #4
DrDaytona
Adventurer
 
Joined: Apr 2009
Location: Eastern Pa-ish
Oddometer: 94
What they said ....

Having assembled quite a few old Italian lovelies over the years, I can say with certainty, there is no certainty, even with brand new parts. Ensuring everything is properly round and of the correct dimension makes life a whole lot better down the road. Further more, while hard metals are difficult to truly screw up by hand, it is always bad practice to polish mating surfaces by hand with a hunk of abrasive. Generally, all you end up accomplishing is making the low spots lower and so forth.
DrDaytona is offline   Reply With Quote
Old 09-28-2013, 07:03 PM   #5
chammyman
Gnarly Adventurer
 
Joined: May 2010
Location: Glasgow, Scotland
Oddometer: 408
we just spin cranks up n the grinding machine/lathe and give em a polish with 400 grit.

A chamfer in the oil holes as mentioned is a good idea.
__________________
1984 Honda CBX 750 FE
1985 Honda VF 750 F
1987 Honda CBR 1000 F
1988 Honda CB 350 SG
chammyman is offline   Reply With Quote
Old 09-28-2013, 07:20 PM   #6
Andy-Gadget
Any bike can go anywere
 
Andy-Gadget's Avatar
 
Joined: Jul 2006
Location: Hobart, Tasmania
Oddometer: 1,316
If you linish the pin, as suggested (400 wet and dry) make sure it is in the direction of rotation, had a boxer BMW eat bearing, one after another, until we finally figured it had been linished in the opposite direction to its rotation.
Linishing (polishing) is done to lay the fibers of the steel over in the correct rotation direction, hand in hand with surface finish, but directional.

BMW cranks are nitrided, and so don't cope well with resizing, don't know about Guzzi cranks, but I would be inclined to linish (polish) only, if they measure withing or even just under, spec.
__________________
"If a man empties his purse into his head, no man can take it away from him.
An investment in knowledge always pays the best interest"
Benjamin Franklin.
'95 Sport 1100 Guzzi,'84 Cali 2 Guzzi, '95 Guzzi mille, '84 R65LS, '84 R100, '82 R100RS, '05 DL650, '72 Bultaco Sherpa T 350, '78 Montessa 348, "00 XR650R
Andy-Gadget is offline   Reply With Quote
Old 09-29-2013, 05:11 AM   #7
Quickv4 OP
Pro Turd Polisher
 
Quickv4's Avatar
 
Joined: Jul 2009
Location: Dickinson, Nort' Dakohtah- Orig. from Wiscowsin
Oddometer: 549
Hmmn, i thought these things were called "tractors" for a reason. For the guys that think taking it to machine shop and having them do everything, is that a bit of overthinking?

I thought just a bit of linishing/micropolishing on the mains just to get that tiny bit of discoloration on it would be sufficient? Maybe im totally wrong and Ill blow this Loop engine up. The motor is totally going back to stock specs, no Hipo cams, lightweight flywheels, big bore kits, etc.

Ill admit though, i havnt taken a mic to the journal yet, which i probably should anyways. Methinks doublecheck the specs, if they come out within a couple thousanths, chamfer the oil holes and linish the crank, throw it back together and tractor on.
__________________
Jerry
____________________________
Great forum and Resource for 1st and 2nd gen Honda V4s SabMagIntercept


www.v4hondabbs.com
Quickv4 is offline   Reply With Quote
Old 09-29-2013, 05:40 AM   #8
Buzztail
NMBBMFBK
 
Buzztail's Avatar
 
Joined: Sep 2007
Location: BUZZTOPIA
Oddometer: 10,774
Do yourself a favor and at least have the crank polished by a machine shop. You can chamfer it yourself before hand. If you can measure the rod then do it yourself too.

The crank polisher spins a belt at high speed while the crank rotates. Not something most can duplicate at the house.
__________________
When there is no way out - Find a way further in.
DL650 DR350 MMS Edition KDX Past bikes ...and an airhead vvv
Quote:
Originally Posted by Mugwest
Quote:
Originally Posted by Buzztail
You shoulda told me to do this a long time ago
My bad
Buzztail is offline   Reply With Quote
Old 09-29-2013, 06:26 AM   #9
anotherguy
Beastly Adventurer
 
anotherguy's Avatar
 
Joined: Jun 2009
Location: the hills
Oddometer: 5,908
Doing it right is never overkill. But it's your party. But if your not sure how to do it leaving it alone is better than doing it wrong.

Why do you think the bearings are smeared? Lack of proper oiling. And I've balanced,ground,polished and chamfered more than a few tractor crankshafts.
__________________
A lie has no feet......it can't stand alone.............
Jason Newsted
anotherguy is offline   Reply With Quote
Old 09-30-2013, 09:18 AM   #10
ttpete
Rectum Non Bustibus
 
Joined: May 2009
Location: Dearborn, MI
Oddometer: 5,244
That crankpin doesn't look bad at all. I'd mike it up and if it was OK, I'd shine it up a bit using crocus cloth and oil. The bearing shells did what they were designed to do, and that is to allow particles to embed in the surface and not score the crankpin.
__________________
10 Ducati 1098 Streetfighter S - "Sleipnir"
09 Kaw Versys
67 Triumph Bonneville TT Special
"The problem with Socialism is that you eventually run out of other people's money" _____ Margaret Thatcher
ttpete is online now   Reply With Quote
Old 09-30-2013, 10:04 AM   #11
anotherguy
Beastly Adventurer
 
anotherguy's Avatar
 
Joined: Jun 2009
Location: the hills
Oddometer: 5,908
There's an oiling issue. Fix it or have it fixed. Why even bother if you're going to do it half assed? Yes it lasted this long but again why not fix it correctly? Compare the oiling holes to the picture I posted earlier.

__________________
A lie has no feet......it can't stand alone.............
Jason Newsted
anotherguy is offline   Reply With Quote
Old 09-30-2013, 03:57 PM   #12
PaulRS
Dutch fool
 
Joined: Apr 2008
Location: Holland, land of tulips and wooden shoes
Oddometer: 718
Did you check and cleaned the slugdetrap?

The inside of the big-end journal of the crank act's like a centrifugal hold to collect any solid particles and in the end enough of the solids will block the oil-passages to the earrings.
Looking from the front of the crank, you'll find an alloy plug.
Once removed you can find this;



Sludge trapped inside there will block the oil-feed to the big-ends.

From the pictures, you caught this just in time and, with a bit of luck, you can polish the bearing surface with a drop of oil and a Scotch-brite pad.

Paul.
__________________
Geht net, gibbet net.
PaulRS is offline   Reply With Quote
Old 09-30-2013, 06:14 PM   #13
ttpete
Rectum Non Bustibus
 
Joined: May 2009
Location: Dearborn, MI
Oddometer: 5,244
Quote:
Originally Posted by PaulRS View Post
Did you check and cleaned the slugdetrap?

The inside of the big-end journal of the crank act's like a centrifugal hold to collect any solid particles and in the end enough of the solids will block the oil-passages to the earrings.
Looking from the front of the crank, you'll find an alloy plug.
Once removed you can find this;



Sludge trapped inside there will block the oil-feed to the big-ends.

From the pictures, you caught this just in time and, with a bit of luck, you can polish the bearing surface with a drop of oil and a Scotch-brite pad.

Paul.
Lots of the old Brit bikes had these. You need to pull the oil galley plugs and clean all the passages out. The three piece crank/flywheel cranks need to come apart to get them cleaned out. Oh, and Ducati twins, too.
__________________
10 Ducati 1098 Streetfighter S - "Sleipnir"
09 Kaw Versys
67 Triumph Bonneville TT Special
"The problem with Socialism is that you eventually run out of other people's money" _____ Margaret Thatcher
ttpete is online now   Reply With Quote
Old 09-30-2013, 06:51 PM   #14
Andy-Gadget
Any bike can go anywere
 
Andy-Gadget's Avatar
 
Joined: Jul 2006
Location: Hobart, Tasmania
Oddometer: 1,316
Any cross drilled pin has a "sludge trap" built in by the design.

This is the pin of an '82 XT600Z, note the sludge.




Quote:
Originally Posted by ttpete View Post
Lots of the old Brit bikes had these. You need to pull the oil galley plugs and clean all the passages out. The three piece crank/flywheel cranks need to come apart to get them cleaned out. Oh, and Ducati twins, too.
__________________
"If a man empties his purse into his head, no man can take it away from him.
An investment in knowledge always pays the best interest"
Benjamin Franklin.
'95 Sport 1100 Guzzi,'84 Cali 2 Guzzi, '95 Guzzi mille, '84 R65LS, '84 R100, '82 R100RS, '05 DL650, '72 Bultaco Sherpa T 350, '78 Montessa 348, "00 XR650R
Andy-Gadget is offline   Reply With Quote
Old 09-30-2013, 08:25 PM   #15
dpforth
no inline fours
 
dpforth's Avatar
 
Joined: Oct 2010
Location: Fantasy, I mean Vancouver Island
Oddometer: 282
Quote:
Originally Posted by ttpete View Post
Oh, and Ducati twins, too.
The singles as well. They have a threaded plug on the circumference of one crank flywheel.
__________________
This species has amused itself to death
dpforth 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 02:52 PM.


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