Honda CB750 Sandcast

Special Copper washer used by Yamiya - Highly recommended for sandcast owners??

4pots1969

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I received 16 CAP NUT + 16 special Copper washer used to improve the waterproofness and the oil pressing
Thank you for expressing me your opinion..

Yamiya : Special Copper washer used.
Reducing an oil leakage from the clearance between the cylinder and the cylinder head.
Highly recommended for sandcast owners...by Yamiya

http://www.yamiya750.com/index.php?main_page=product_info&cPath=21_51&products_id=2064

« Last Edit: April 12, 2014, 05:24:21 pm by 4pots1969 »


kp

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OK for the technical Gurus out there, why is this so. I'm interested
Yabba Dabba KP


steff750

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Quote
OK for the technical Gurus out there, why is this so. I'm interested

yes and why are you using domed nuts


4pots1969

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Why to use domed nuts? And not just the copper washers? It is the question..?
The use of nuts with a dome (cap) besides copper washers assures a perfect waterproofness at the level of the threading of studs especially on those for the greasing..
The dome of the nut acts as completely hermetic cap in both senses.
« Last Edit: April 13, 2014, 09:35:25 am by 4pots1969 »


4pots1969

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OK for the technical Gurus out there, why is this so. I'm interested

Hello KP, Know that you are aimed not at all by my words.
And if you thought of it I am totally sorry about it.
I like your analysis and your reflection on the various subjects.

Sincerely, Gérard
« Last Edit: April 13, 2014, 10:25:26 am by 4pots1969 »


Steve Swan

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Gerard, i'll let KP talk for himself, but knowing KP as well as i do, i am certain he sincerely wants to hear why to use these nuts and washers.

the great part with these discussion boards is the worldwide community we have.

the down side to these discussion boards is the meaning of what we are saying either gets misunderstood or lost.

i am always glad to hear from all of our world wide friends.


kenhan

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If you take a look at Yamiyas pictures they have only changed the outer nuts. Is it only necessary on the outers or did they just show an example on using the nuts?

/Ken

1969 CB750 Sandcast #5084 - running
1969 CB750 Sandcast #5128 - Running
1970 CB750 next project
1975 K2 (K3-5 don´t exist in Sweden) - Running
1981 Goldwing 1100 Interstate


4pots1969

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I think personally that it is only an example even if it is not I agree on it the best..


Riccardo

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I think is correct chancge all the nuts and coppers, if they not go in contrast with cams or cam towers.
The leak problem can be real for each stud.
Change all or nothing.
Only a question on the quality of those nuts, are they Japan or China or Vietnam quality?
Sometime many reprop parts are poor quality, are only beautyfull to see them.
Riccardo
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4pots1969

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Hello Riccardo,
Yes I agree: change all or nothing!!
This remark is very relevant.. It is true that I had not thought has this small very very important detail of the quality!!
 How to know where from come these nuts?
« Last Edit: April 14, 2014, 09:17:31 am by 4pots1969 »


kp

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Absolutely Steve, Gerard, my request is for other members or anyone to tell me (and maybe other members) why this particular modification is necessary. Is it because oil seeps from the cam area?
Yabba Dabba KP


Steve Swan

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Gerard, I will be very interested to hear your evaluation of these washers/nuts.  i remember very distinctly my old 4779 had an oil weep at the cyl/head joint.  Autumn 1970, i bought a SnapOn impact screw driver to remove the screws fixing exhaust flanges to head, so i could do a good cleaning because of burned on oil.  my E2241 weeps similarly. despite fitting a "sticky" head gasket.  Disappointing.... as i thought the "sticky" head gasket would do the trick.  So, at some point, i'm going to have to pull the engine, so i can do what's necessary to stop the weeping.  too bad the engine can't be dropped in the frame by removing the mounting bolts in order to remove the cam cover. 


4pots1969

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As you know the oil arrives under pressure by the wells of studs 1 & 3 and he certainly has to have there oil leaks through the top threadings because the pressure is important and by putting these domed nuts the waterproofness is restored..

And for others it also avoids that the oil infiltrates by the threadings and comes down in by the wells of studs..

« Last Edit: April 13, 2014, 07:26:58 pm by 4pots1969 »



4pots1969

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Hello Pete,
Yes, Yes, Yes..Thanks for this information..
On the other hand there is only 4 has cap on 16?  It is certainly for the tender spots of oil pressing?
CB750F2 supersport NUT, CAP, 8MM  OEM number: 90443-107-000
Copper sealing washers : OEM number: 90441-377-000  washer special Spy?? photo (no simple copper washer)

I am going to make a pre-assembly with the Holders of Camshaft to see if domes nuts go well everywhere?
« Last Edit: April 14, 2014, 05:27:47 pm by 4pots1969 »