Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Drew400 on October 06, 2014, 08:31:03 PM
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Hi all,
I will preamble this new thread with the announcement that I'm about to start my engine rebuild. Regular readers will know that this is a first for me and so I'm ever so slightly nervous of turning my restoration project into a piece of non-running living room art!
So, here's the first in probably a long series of questions: should I be using a jointing compound to stick the crankcase halves, etc. back together? If so, what substance do you recommend?
Cheers,
D.
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I used blue hylomar, a very thin smear is all that's needed.
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I'd definitely use one. I used Loctite 5922 non-hardening flange sealant. I think Yambond is the preferred stuff.
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Thank you both.
Cheers,
D.
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Hondabond but,Hylomar is cheaper ;)
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Ordinary silicone is OK but ONLY if used VERY THINLY so that there is NO squidge into the crankcases
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Used Three Bond ... They say it's the same as the factory stuff.
No leaks to date.
Other threads on this ie which faces to use it on etc.
I used a small syringe to apply it sparingly(no needle of course)
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Three bond for crankcase halfs, a light coating of hylomar on all the others, that is my choice, stay away from silicon as it sqeezes out on the inside and snaps off clogging up the oil pump gauze
Pete
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I can remember when orange silicone rtv was all the rage ...mostly on side cases....nobody would spend cash on new gaskets.
It was ahead of its time that high viz look ! ::)
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The worst was in my opinion bloody red hermite saying that if you was buying a bike you saw it and knew what a bodge job
Cheers
Bitsa
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A most enjoyable and illuminating thread (or is that a smear?).
Cheers all,
D.
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Hahaha. That is very true Bitsa.
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Drew
Like the smear bit
Cheers
Bitsa
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While I appreciate and take note of Bryan's advice of silicone, I wouldn't get that anywhere near any engine unless it was absolutely specified in the manufacturer build instructions.
It is a very useful material for some applications but just not in these engines with small oilways, and as Pete says you get alot of stuff on the oil pickup. I got a picture of one I took years ago of the oil pickup in a Z650 that looks like a pizza there are so many coloured bits stuck to it.
If all the surfaces are good condition then most of any sealant you put on them gets squeezed out so as the others say only the smallest amount is required of whichever one you choose.
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As one who worked on these for many years in the trade, long before you could lay hands on the genuine Honda, or Yamaha, stuff we used RTV all the time and if used as said you dont get any on the filter screen or in the oilways
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As one who worked on these for many years in the trade, long before you could lay hands on the genuine Honda, or Yamaha, stuff we used RTV all the time and if used as said you dont get any on the filter screen or in the oilways
+1 on that Bryan, I used to use it ,as it was all there was around and a revolutionary product in the 70's. Suppose there are far more ' forgiving' compounds around today though. When I put my latest engines together soon I will be on a new learning curve as what's best to use. I must admit, I too have seen oil holes blocked with orange silicone on PO 's rebuilds but I only ever applied a smear as knew the pitfalls.
Cheers .. AshD
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I can take some comfort from all this advice in that, whilst I have discvovered plenty of old damage inside my poor old engine, there's not a hint of any old sealents, etc.
It seems that I'm about to change all that... but only with the teeny weeniest application, as advised!
D.
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You may laugh boy's but some years ago i had a engine in for a re-build and the casings had been put together with chewing gum. Do not ask me what brand but, the engine had no leaks.
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Chewing gum has many properties and can as we know survive for many years on pavements etc.
An aircraft maintenance fitter told me he found plenty of redundant rivet holes plugged with the stuff then painted over...
On a USAF F1-11 bomber !
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Chewing gum is also known for being petrol-proof. Many a vehicle in WW2 had a holed fuel tank plugged with the stuff. Probably some aircraft as well.
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Bryan, I wasn't intending to shoot you down on the silicone, suppose I've got a bit of a mortal fear of it having opened up some really grim rebuilds in which they'd just used so much of this stuff that it caused more problems than cured anything.
So sorry for putting you on the spot and to offer an apology for making it sound like that.
Nigel.
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No offence taken mate, I have seen a filter screen nearly bunged with excessive Hylomar before now! i think it comes from the old Brit iron where if the goo wasn't at least 1/8 inch thich you still got leaks---still got them then most of the time!
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As a long term rider and sufferer of old Brit bikes I had plenty of experience of rebuilding engines!
I usually used Red Hermetite(because that's what my dad had in the shed :D) and never had any problems.
I think most problems back then were caused by ham-fisted owners levering cases apart and damaging the joint faces. Then they used far too much sealant to try and fill the damage. A lot of owners never seem to have heard of tightening down in an even sequence to avoid distortion and WTF is a torque wrench?
No wonder they leaked. :-\
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I don't think many people think it through properly in that the better condition and more precise the engineering of the joint then the less sealant it usually requires to prevent it leaking.
I know we repeat it on here, but for some it's not easy to determine just how little sealant you need especially if they are new to this stuff.