HELP! Crankshaft Main Bearings!!!

[eddietheo]

Hi guys

Would really appreciate your assistance on this one!!

Recently broken engine down and sent away to Engineers as I thought i'd get the tolerances checked by a reputable professional!!

Unfortunately, they don't know and I forgot to advise them of the various different size shells and they weren't ever aware!! Anyway they removed and bagged them all up but have advised the the bottom end was fine and nothing needed changing but advised just to replace standard size shells!! Thats when panic set in and I had realised what they had done!!

On checking the Crankcase it is coded AAAAA. However, I cannot read the codes from the crankshaft so do not know exactly what colour shells are required for what journal!! Having spoke with David Silver they advise with AAAAA it can only be either Yellow or Green but don't have any Yellow in Stock!!

I was just considering whether to take pot luck and replace existing shells but don't know which came from where!!! Alternatively try using Plastigauge and trial and error. All the shells look exactly the same and there is no colouring on them and the engineer could not advise of different sizing!!

Could it be just possible that as its AAAAA they also happened to use the same Shells?? The engineer tried to measure but as we all know the tolerances are so fine... Fortunately he kept the big-ends in situ with the con-reads so happy there!!!

Any suggestions gratefully received!!!

[Trigger]

Wash the crank in petrol to see the crank codes  and then come back, don't ask sliver about these they don't have a clue 

[eddietheo]

Trigger

Thanks will do but I tried to do it with meths earlier but didn’t do anything!!

Will try with petrol!!

[Bryanj]

If you are very good with a micrometer and have what is called a ball anvil you can check the thickness of the shells and compare them, sounds like the "experienced" engine driver never seen a Japanese engine!

[Trigger]

Actually DS are correct in this instance. The ONLY 2 colours that could have been fitted with those crankcase markings were green or yellow. Yellow is the thinnest shell Honda did on the 500, so fitting green shells in all journals would be fine as they are just slightly thicker and so long as you run it in really carefully you should be fine. Members have fitted all black shells in the past when markings have been missing or have faded away, those are the thickest shell Honda did and are 3 sizes bigger than yellow, they just ran them in real gentle and they worked just fine. If it works with 3 sizes bigger it will work even better with 1 size bigger and that's presuming they weren't all green in the first place, which TBH they probably were as that and brown are the 2 most common colours used.

Yes, Sliver is correct but, if they were green in the first instance and he replaced them with yellow (with a old worn oil pump) then he would have a problem. Also I reclaim con rods so if I had been there before because of a oval rod, then it doesn't matter what codes you are looking at 

[eddietheo]

Hi Guys... Thanks for your inputs!

I have thoroughly cleaned the Crankshaft with BP's finest and can't find any markings on the Crankshaft! I know where they should go as DS sent me a picture of a new one!!

I will try and post here some pictures but failed last time i think due to the size of iPhone pictures.

The only clear marking I have on the crankshaft is a N or a Z next to No 1 Big end!! (Depending where you look at it!)

Is it possible that they are all the same size therefore and maybe originally should have been all Yellow?

If pictures do not upload if you PM me then your email address then I cold send you them via Email!!!

Much appreciated with your input this is driving me mad!!!

Rgds

[SteveD CB500K0]

There's a FAQ here on uploading pictures.  http://www.sohc.co.uk/index.php/topic,1825.0.html

I've just increased the size allowances as storage is getting cheaper and phone cameras are getting bigger!

Steve

[eddietheo]

Steve

Pictures on my iPhone come out at 2.6 to 3.6 Mb I'm afraid!

Cheers

[SteveD CB500K0]

There are free apps for iOS - I've not tried them as I resize in Windows before uploading.

Steve

[K2-K6]

Is there any reason that you can't just measure the crank journals to compare with tolerance range that will give you the designated shell colour?

Is there a spec list available that lists notional bore and journal sizes,  it must have been done during production to identify designation of both sets of ID codes.

[paul G]

Use IMGUR upload the pictures and then paste the links.
Dosen't matter what the picture size is as it is a hosted picture 

[eddietheo]

Thanks guys... don’t think I have much of an option but will fit the greens!!

Thanks for
Your feedback!

[Bryanj]

Nobody i know can measure acuratly enough, Honda used air gauges