Author Topic: CB400Four cylinder bore clearance NOS pistons 51,75  (Read 218 times)

Offline eem46

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CB400Four cylinder bore clearance NOS pistons 51,75
« on: February 04, 2020, 12:28:47 PM »
Dear All,

Just got my Honda CB400F cylinder back from wetblasting, gonna mount NOS pistons with a third oversize, so 51,75mm.

Ofcourse the machine guy will measure each piston and match that size  to the sleeve/bore.

Which clearance must he take? As tight as possible? 0,04mm or 0,05mm or 0,06mm (sorry no inches)

Please advise, thank you.

Kind regards,

Emiel

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #1 on: February 04, 2020, 12:49:37 PM »
Using OEM Honda pistons, Trig works to a clearance of 0.0203mm which is equivalent to .8 of a thou in inches. The clearences you are mentioning are WAY to high, even for pattern pistons.
« Last Edit: February 04, 2020, 12:52:12 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline eem46

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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #2 on: February 04, 2020, 02:32:55 PM »
Hi Julie, good that I ask than :-)

I will sent the information to my machine shop.

Thanks for the quick reply.

Kind regards,

Emiel

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #3 on: February 04, 2020, 02:35:38 PM »
Hi Julie, good that I ask than :-)

I will sent the information to my machine shop.

Thanks for the quick reply.

Kind regards,

Emiel
You are welcome Emiel. It sounds like you are making good progress.
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline eem46

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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #4 on: February 04, 2020, 02:47:25 PM »
I am working on two bikes at the same time, not very efficiënt, one complete stock, with many NOS parts (including exhaust header) CMSNL loves me,  and one fast version (big bore, alu rims, bored carbs by Rick Denoon, Kevin TTR parts, stage two welded web cam, stainless Motogpwerks exhaust, alu Koni's, skimmed drilled disc, Hyperpro front springs, Pro bolt titanium bolts, K&N filters, BT45's)
So yeh enough to do! :-)

@Julie : PS: tolerance piston for aftermarket big bore kit? 0.03mm?

Kind regards,

Emiel
« Last Edit: February 04, 2020, 02:50:03 PM by eem46 »

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #5 on: February 04, 2020, 02:54:51 PM »
I am working on two bikes at the same time, not very efficiënt, one complete stock, with many NOS parts (including exhaust header) CMSNL loves me,  and one fast version (big bore, alu rims, bored carbs by Rick Denoon, Kevin TTR parts, stage two welded web cam, stainless Motogpwerks exhaust, alu Koni's, skimmed drilled disc, Hyperpro front springs, Pro bolt titanium bolts, K&N filters, BT45's)
So yeh enough to do! :-)

@Julie : PS: tolerance piston for aftermarket big bore kit? 0.03mm?

Kind regards,

Emiel
Gosh, you are very adventurous, good luck with both. I'm  not sure about big bore kit pistons clearance as Trig doesn't get involved with them at all but, pattern pistons such as Cruzinimage, Trig would work to 0.0254 clearance, which is 1 thou of an inch. The piston manufacturer should be able to tell you the info you need.
« Last Edit: February 04, 2020, 03:04:26 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline SteveD CB500K0

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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #6 on: February 04, 2020, 05:11:26 PM »
Rick Denoon.

Now there’s a name from the past.

Assume he’s still in the business?


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Offline eem46

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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #7 on: February 05, 2020, 08:15:15 AM »
He did my stock CB carbs very nicely, quick work and quick shipping from Canada. But yeh that was 3 years ago, he was also working on a speed throttle for the CB 400 four carbs, I got one of his prototypes, but didn't test it yet to be honest.


Offline SteveD CB500K0

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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #8 on: February 05, 2020, 10:53:29 AM »
(Quite) a few years ago he launched a 400/4 newsletter. I signed up but only ever got one.

There again, the last blog I posted was 5 years ago…

Life eh?


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Offline mattsz

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Re: CB400Four cylinder bore clearance NOS pistons 51,75
« Reply #9 on: February 05, 2020, 02:26:15 PM »
(Quite) a few years ago he launched a 400/4 newsletter. I signed up but only ever got one.

His site is still active:

http://www.denoonsp.com/index.htm

During a 400/4 cam chain google search, I stumbled across his first newsletter (which, BTW, has a very nice description of the cam chain arrangement).  Digging down into his site a bit, I found two other newsletters.  Hopefully it's ok to link to them here - they are publicly available on his site:

http://denoonsp.com/user/image/v1-issue1.pdf

http://denoonsp.com/user/image/v2-issue1.pdf

http://denoonsp.com/user/image/v3-issue1.pdf

 

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