Con rod stamp markings

[beemsquar]

Hello all,

I need some help with the stamp  markings on my con rods.

I am about to reassemble the crank and add the new bearings etc, but I am unsure which way round the con rods should face.

I didn't take them off to see how they go back as the engineer who measured the runout for me removed them.

They are stamped with a different  number of dots on each one from 1-4, which I guess is number 1 being the left hand side of the engine and number 4 being the right hand side if you were sat on the bike?

But should the stamped marks be  facing forward or rearward again with the engine the right way up and as if you were sat on the bike?

Any help would be much appreciated!

[Bryanj]

There should not be any stamped in dots on the rods at all, pictures may help

[beemsquar]

both pictures are the  same con rod, trying to figure out which way should face forward and which piston they correspond to.
You can see this one has 4 dots stamped into it the others have 3 , 2 and 1 on each one.


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[Woodside]

Has it been apart before...could a previous owner have marked these on an earlier rebuild ."?

[Chris-freckle]

Hi the dots have been put on after manufacture probably by a previous owner, not got manual to hand for direction, sorry

[beemsquar]

Maybe it was the engineer who stamped them then. I've been over all my photos I took before I gave it to them and can't see these marks.

They are a professional engineering company and have all the equipment to do that kind of work,  I paid them to check the crank was Ok and to work out which bearings I needed.

I have all the bearings now based on their measurements, but need to work out how it goes back together.
Am I right in saying piston one would be on the left? Is this how you would normally refer to it?
I can't see the number 2  in that picture,  let alone the other con rods, that's why I sent it to be measured.

[NigelWilmshurst]

I also gave my stripped engine to a very reputable engineer to measure all the bearing journals etc, and my con rods were marked the same, he also gave me a diagram for re assembly, I will check my rebuild photos and get back to you, make sure you have a parts washer to clean all the engine parts and blow off cleaning fluid with an air line, oil all bearing surfaces during assembly and only rebuild in a very clean dust free area, don't forget to service the oil pump.

Follow the manual word for word and you will have no problems.

[Bryanj]

Way back when you used to do that to mark which bore but on a new higher stressed (relatively) engine I would never do that as it creates stress points

[beemsquar]

Cheers for your help guys.

I will contact the engineer this morning to see if he can shed some light on it.
It was nearly 3 months ago now though,  as that's how long it's taken to get all the shells together,  seemed to be a European shortage or something!
I have got a small parts washer, I washed most of the parts last night, dried them off with an airline and bagged them all up to keep them clean.
A newbie question for sure, but can anyone shed any light on which bore is number 1? Is it the same on any vehicle?  It's a steep learning curve but I'm getting there.

I would love to know if anyone has any recommendations for engineering books etc that give the basic terminology and procedures to follow when building an engine.

[hairygit]

Number one cylinder is the left hand end one as you sit on the bike.

[Trigger]

Can not understand why company's mark up like that, what is wrong with tipex or a engineering pen.   

[NigelWilmshurst]

I replaced my con rods as the crank lays in the lower case with the con rods pointing to the front of the engine, original letters in some form of ink facing downwards and the new engineers punched dots facing towards you.

I checked another cb750 engine I have stripped and is the same as above, hopefully you can get on with the build now, good luck mate and ask away anything else that is not clear.

Nigel

[NigelWilmshurst]

I also ordered some plastigauge from ebay and double checked all bearings after bolting up the crank cases, same for the 4 No camshaft holder surfaces, measure twice to build once!

[beemsquar]

Cheers guys!
One of the reasons I sent it to a specialist was because I couldn't 100% Read the letters and numbers, I couldn't decide if it was a 1 or a 2.
Glad to have someone with your experience on here brian to confirm everything! I will rake some more photos soon and post.
 After the engineer measured the crank runout etc he plastigauged the cases and worked out all the bearings for me, costly but he came out with different shell colours to me, so glad I got a professional to check!
I ended up with all green main bearings and 3 green and 1 yellow for the big ends.
 Took ages to arrive and in dribs and drabs.

I called the engineer who stamped the con rods yesterday and he confirmed that if assembling upside down the dots should be facing the back of the engine with the con rods hanging down. Torqued everything up and RE assembled the top crankcase, should bolt it all together today!

[Dave_Canada]

Just mess with the brightness and contrast in a photo editor (gimp is free). markings can stand out.

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