Honda CB750 Sandcast
The Restoration Shop => Engine Mechanical => Topic started by: 4pots1969 on April 12, 2014, 05:17:01 pm
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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
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OK for the technical Gurus out there, why is this so. I'm interested
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OK for the technical Gurus out there, why is this so. I'm interested
yes and why are you using domed nuts
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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.
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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
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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.
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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
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I think personally that it is only an example even if it is not I agree on it the best..
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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.
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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?
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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?
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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.
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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..
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The later F2 sohc model has a similar nut and copper washer as standard fitment by honda
pete
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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?
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No problem in the assembly of Holders, 2/3 mm minimum of tolerances everywhere.
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The washers 90441-377-000 was supercede by coppers 90441-422-000