Author Topic: 400F factory crank markings question  (Read 906 times)

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Offline ag12680

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400F factory crank markings question
« on: October 10, 2014, 02:47:56 PM »
I'm building one of two 400F engines I have and noticed that the con rods and corresponding crank weights are marked with the bearing size and a number.  On the stock crank in the photo they are marked: 1 2 2 2 with the "1" rod on cylinder 1 near the stator.

On the motor I'm building now, the rods are marked the same, but I had the crank lightened by APE so the corresponding markings are long gone.  I pulled the motor apart long ago and marked the rods which have the same sequence except reverse of the other crank I have.

I'm replacing the "C" big end bearings which are they same for all rods.  Do these numbers indicate anything of significance as far as their placement on the crank?

Getting old, so I can't remember as well if there is no photographic evidence.

Thanks!

Andy

Offline thirsty 1

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Re: 400F factory crank markings question
« Reply #1 on: October 10, 2014, 07:40:33 PM »
this should help.
73' CL125, 75' CB400F, 16' KTM 1190R, 05' KTM 525EXC

75' CB400F  -  http://forums.sohc4.net/index.php?topic=127295.0

My 79 CB750F for fun   ----   http://www.dotheton.com/forum/index.php?topic=19923.0

Offline thirsty 1

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Re: 400F factory crank markings question
« Reply #2 on: October 10, 2014, 07:47:06 PM »
http://www.sohc4.net/cb400-manuals/

you should print this out. I'm not sure if you have it or not? The "C" is the bearing size and is committed to the journal it was measured to. So YES

« Last Edit: October 10, 2014, 07:48:56 PM by thirsty 1 »
73' CL125, 75' CB400F, 16' KTM 1190R, 05' KTM 525EXC

75' CB400F  -  http://forums.sohc4.net/index.php?topic=127295.0

My 79 CB750F for fun   ----   http://www.dotheton.com/forum/index.php?topic=19923.0

Offline ag12680

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Re: 400F factory crank markings question
« Reply #3 on: October 10, 2014, 10:57:50 PM »
Thanks..  Yes, I have this doc and have confirmed the bearing sizes.  What has me scratching my head is the sequence of the other numbers 1 2 2 2 respectively and why the rod marked 1 would be swapped on the two cranks - unless I screwed up and mismarked the rods during disassembly.

In other words, does it matter which rod goes on which journal if all the bearings are the same (e.g., new "C" bearings)?

Thanks again!

Andy

Offline thirsty 1

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Re: 400F factory crank markings question
« Reply #4 on: October 11, 2014, 10:02:58 AM »
Nope. You "should" be fine but I'd plastigauge them as there assembled just to make sure.
73' CL125, 75' CB400F, 16' KTM 1190R, 05' KTM 525EXC

75' CB400F  -  http://forums.sohc4.net/index.php?topic=127295.0

My 79 CB750F for fun   ----   http://www.dotheton.com/forum/index.php?topic=19923.0

Offline ag12680

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Re: 400F factory crank markings question
« Reply #5 on: October 12, 2014, 05:42:15 PM »
Thanks for your help!  The only other thought i had was that the numbers correspond to weight which is a moot point since the crank has been modified...