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Author Topic: Cb400f head thickness  (Read 3501 times)

amx1992

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Cb400f head thickness
« on: August 24, 2020, 08:33:53 PM »
The head on my bike looks like it has been skimmed badly, more on one end than the other. Does anyone know how thick the stock head is so I can work out how much has been removed?

Cheers
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amx1992

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Re: Cb400f head thickness
« Reply #1 on: August 25, 2020, 05:59:29 PM »
Does anyone have a 400 head and a micrometer or even calipers, they could measure rocker cover face to head gasket face for me, bit stuck atm.
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Offline Trigger

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Re: Cb400f head thickness
« Reply #2 on: August 25, 2020, 08:25:32 PM »
Head is 52.50 at the stud points in the picture indicated in red ;)


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amx1992

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Re: Cb400f head thickness
« Reply #3 on: August 25, 2020, 08:40:44 PM »
Absolute lifesaver, cheers trigger. Ill find out tomorrow how much has been skimmed off, i have a horrible feeling its a lot.
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Offline Trigger

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Re: Cb400f head thickness
« Reply #4 on: August 26, 2020, 08:41:34 AM »
If a 350 or 400/4 head has been skimmed, it is very easy to tell as, the head surface is very close to the bottom fins and will slightly touch the fins if a lot is skimmed of  ;)

If the head surface is nearer the fins on one side of the head compared to the opposite side, then that is normal to old Honda castings .
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amx1992

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Re: Cb400f head thickness
« Reply #5 on: August 26, 2020, 05:53:15 PM »

Measured it and its only 0.05mm difference between sides, however 0.6mm (22 thou ish) has been skimmed off. Wonder if i can i get away with making a 1mm base gasket to compensate
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Offline Trigger

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Re: Cb400f head thickness
« Reply #6 on: August 26, 2020, 06:29:17 PM »
I am not sure where you are going with this. I skim heads day in, day out, so what is the problem with a head that has been skimmed. The aftermarket head gasket that you will be using is a lot thicker than the original Honda one that was fitted at the factory.
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amx1992

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Re: Cb400f head thickness
« Reply #7 on: August 26, 2020, 06:52:42 PM »
Fair enough, just thought 0.6mm was lot off the head, obviously i was wrong.
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Offline robvangulik

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Re: Cb400f head thickness
« Reply #8 on: August 26, 2020, 07:58:27 PM »
So long as the valves don't reach the pistons, you'll only have more compression, which will benefit performance.
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