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Conrod bigend bearings.

PostPosted: Mon Jul 07, 2014 10:53 pm
by Kerppele
My -80 CX500 engine jammed last summer, and my friend is repairin it now. I bought "new" (used) camshaft and conrods from eBay, without bearignshels. And now I don't have a smallest idea which ones I supposed to buy new. On the camshaft is painted BB letters and D & 72 have been all ready in mold. Conrods have C2 and D1 curved on, 415:15 have been n mold.
I try tomorrow add few photos of those parts, if it makes any help.
Hoping to get cruising yet this summer..

Re: Conrod bigend bearings.

PostPosted: Mon Jul 07, 2014 11:01 pm
by Gman
There only a limited amount of colour coded big-end shells available now.If you are in the US ask on this forum,

I think there's someone on there who can get the cranks rebuilt and shells.

The information on matching the shells,if you can get them,is in the Workshop manuals and there are some download links for E versions(PDFs) of the some manuals.

It's sometimes more cost effective to try and get a decent running engine.

HTH :)

Re: Conrod bigend bearings.

PostPosted: Sun Jul 13, 2014 7:37 pm
by Kerppele
Well, i do live in finland..
Decent running engine in germany isn't so expensive, but after delivery and taxes, it is whole different story.
But now I have decent cranksaft with "BB" paint marks on it, are those "the" letters which I schould compare to tablet?
Allso I have conrods with A1/A2/C2/D1 letters carved.
Am I wrong if i say that i could use "yellow" shells when using A1/D1 pair with "BB" marked cranksaft?
I hope so, because those are still available..

Re: Conrod bigend bearings.

PostPosted: Tue Jul 15, 2014 3:35 pm
by Gman
This should help,


It has been said that the shells are so slight in their difference that even the next size thicker could be used because of crank wear but I've never tested this.

Also I have a friend in Finland who may be able to help.I'll ask him if it's ok for you to contact him.

Re: Conrod bigend bearings.

PostPosted: Wed Jul 16, 2014 6:14 pm
by Kerppele
I would be more than delighted, if someone tell me how to continue.
I'm not sure, am I reading right marks from old conrods and crank.
I have allready chain,tensionerparts and four Green shells in basket (
Just waiting that someone could confirm those shells are even close rightones.

Re: Conrod bigend bearings.

PostPosted: Wed Jul 16, 2014 9:56 pm
by Gman
The best I can suggest is that if possible you take the crank,rods and shells to an engineering company that does Crankshaft engine work and get them to check the shell gaps,when fitted,with a Plastiguage.
Also if you have or have not fitted shells before treat them and the crank like eggs e.g they are fragile on fitment and the surface of the crank shaft is quite soft and can be damaged easily so be very very careful when fitting the rods so as not to score the surface.I ruined a 2nd hand crank by letting the rod stud bolts scratch the surface when fitting it :roll:
Also once fitted you should use loads of clean engine oil on the shells before fitting the rods and once the engine is back together drip clean oil down the holes in the head where the pushrods go to make sure the bottom end is fully lubricated.

When starting the engine for the first time don't let it rev too low.Hold the engine around 2,000/3,000 revs for a minute or two to allow the oil pump to get the oil around the engine fast.

I actually use Moly Running in paste on my shells but it's not easy to find these days.

Re: Conrod bigend bearings.

PostPosted: Thu Jul 17, 2014 3:39 pm
by Kerppele
Thank you very much.
I ordered those parts and let's see what there is coming.
I will tell how this goin on.

Re: Conrod bigend bearings.

PostPosted: Fri Jul 18, 2014 7:14 pm
by Gman
Both my CX500 engines have been rebuilt by me with new shells but 2nd hand crank shafts and I had the cranks checked and machine polished at a local engineering company.I know the gaps between the new shells and the cranks are not ideal e.g a little wider than if they were all brand new.Both engines run fine with no noticeable loss of power.
The only small downside is that if I run the engines above 6,000 rpm for any length of time they use oil.They don't smoke,just use oil so I check my oil frequently.This means I try to keep my top end speed below 65 Mph and not over rev the engines on acceleration.This does NOT mean I ride slow as these engines are a good and powerful power-plant and very forgiving.

Note:As I've got to know these engines I can tell if the oil needs topping up as the gearboxes become a little,"Clunky" rather than the nice smooth action they normally give.If I go on a longish day out and cover a lot of miles e.g 200+ I always keep a small Bottle of oil with me just in case.I've not had to use it yet but have had to top up when I got home if I've been up over the Yorkshire moors where I've had the engine under load and perhaps done a little,"Spirited" riding ;-)

As these engines run fine on cheap Supermarket car oil the cost is minimal :)
On flat commuting the engines use next to no oil and I know that even some modern motorcycles use more oil than my CX500s :mrgreen:

I also run my engines on Molyslip ... 23356bd251

engine additive so it helps protect them.Half bottle each oil change around 3,000 to 4,000 miles.