Author Topic: CB750K0 6mm Head Bolts In Tightening Sequence  (Read 2342 times)

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Offline markb

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CB750K0 6mm Head Bolts In Tightening Sequence
« on: December 28, 2007, 07:15:18 AM »
I'm putting the top end back on my motor this weekend and I have a question.  It's obvious in all my manuals what the sequence for the 8mm nuts is but when do you tighten the 6mm bolts (the four under the sealing rubbers and the other outside one), before or after the nuts?
Thanks,
Mark
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Offline bryanj

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Re: CB750K0 6mm Head Bolts In Tightening Sequence
« Reply #1 on: December 28, 2007, 08:48:55 AM »
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Offline markb

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Re: CB750K0 6mm Head Bolts In Tightening Sequence
« Reply #2 on: December 28, 2007, 10:12:00 AM »
Thanks, that makes sense because after the 8mm nuts compress the head gasket the bolts will get loose.  I just feel better with a 2nd opinion and a chance to think about it.
 
1969 CB750 sandcast #97 restored - Sold Restoration thread link
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1970 CB750 K0 restored - Sold
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Offline danfr

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Re: CB750K0 6mm Head Bolts In Tightening Sequence
« Reply #3 on: March 24, 2012, 12:34:01 PM »
I have both the Hondaman book and the Honda maual. I cannot find the torque specs anywhere for the 6mm head bolts! Anyone?
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Offline MCRider

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Re: CB750K0 6mm Head Bolts In Tightening Sequence
« Reply #4 on: March 24, 2012, 01:23:46 PM »
I'm putting the top end back on my motor this weekend and I have a question.  It's obvious in all my manuals what the sequence for the 8mm nuts is but when do you tighten the 6mm bolts (the four under the sealing rubbers and the other outside one), before or after the nuts?
Thanks,
Mark
My opinion is that you tighten them down centers first then the outside. This will settle the head into gasket and into the dowels. Center first then you roll the wrinkles out to the outside, figuratively speaking. Then you go for the head nuts.

After that yes the 6mm will be loose again. at this point they are useless and may be removed. (Did I say that?)

Tighten them down to something reasonable, 8 ft lbs or so, just so they won't back out and rattle.

Foir those who may be reading this and care, I'll mention a semi related point. When you want to disassemble the head, REMOVE THESE FIRST. If you loosen the head nuts first, the head will relax into the 6mm bolts and the effort needed to remove them will skyrocket and one will often destroy them getting them out.
« Last Edit: March 24, 2012, 01:26:13 PM by MCRider »
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Offline danfr

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Re: CB750K0 6mm Head Bolts In Tightening Sequence
« Reply #5 on: March 25, 2012, 01:15:21 AM »
Hey, thanks for the reply. I already had the 16 head nuts torqued down and tightened the described bolts tightened to a mear 8ftlbs. Thanks for your help!
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Offline mycb750k6

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Re: CB750K0 6mm Head Bolts In Tightening Sequence
« Reply #6 on: March 25, 2012, 08:29:40 AM »
I recently helped a guy put his 78F head on and his shop manual had a head bolt torque sequence quite different from the early Ks that included the 6mms in the sequence. That's also the motor that has the weird copper washers in the 8mm mix. On the Ks they are just done last after the 8s are tight.