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RD350LC Copper head gasket sealing


DougW
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Sealant  

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  1. 1. Pick a sealant

    • Stag Wellseal
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    • Dirko (proper rtv gasket goo)
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    • Something else
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Assuming I actually finish making the 0.5 mm copper head gasket for the 350lc, wot sealant wud u use mister ?

(annealed,obvs)

 

( Dirko is grey “proper” gasket sealant, I think, like threebond/yamabond/anybond)

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I like Dirko - its a step up from threebond/yamabond etc imo.

However, I did try a pair of copper head gaskets many years ago on the RG500 which included using some Dirko and it was a waste of time and the gaskets did not seal.

You might have better luck but I'm not convinced by copper head gasket unless they have some sort of crush sealing ring around the combustion chamber.

How come your going down the copper gasket route, I think they are multi layer on the 350, can you just split the gasket layers and use a single leaf (or two) from the standard gasket to get the thickness you want ?

I actually do this with my RG500 motor, I use a single leaf and discard the spacer gasket in the middle and the leaf on the other side.

I then seal the bottom of the "leaf" gasket onto the cylinders with this stuff to take up the small imperfections and help seal the coolant passages:

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-super-300-form-a-gasket-sealant

Really easy to apply, just paint it on the cylinder, its thin ish but sticky and non hardening.

(Pretty sure I read somewhere people also use this with copper head gaskets!)

80057.jpg?lossy=1&strip=1&webp=1

Dan

Edited by dannn
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Only multi layer on YPVS as far as I know, my exhaust ports are a bit high, 0.25mm base gaskets and 0.5 mm head gasket should give around 1mm squish. 

Standard head gasket 4L0 1.2 mm

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2 minutes ago, DougW said:

Only multi layer on YPVS as far as I know, my exhaust ports are a bit high, 0.25mm base gaskets and 0.5 mm head gasket should give around 1mm squish. 

Standard head gasket 4L0 1.2 mm

I've run huge squish (~2mm) for years without issues...I certainly would not stress about 1.7mm!

Anyway, I defo would use super 300 on the copper gasket if you go that route.

Dan

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I tried that copper spray as well (can't remember if before or after the Dirko).

Anyway, it was horrible stuff, very much like spray paint and just made a mess everywhere.

I think its more used to stick the head gasket in place for assembly.

IMO the super 300 is the stuff you want. 

Edited by dannn
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Why would you try to use a sealant on a copper gasket?

It's whole porpoise is that you stick it in fire and get it cherry hot and when you quench it in cold water it's the ultimate bodge material. So soft that it will form to any machining irregularities and when it has waited a couple of days it's as strong as it ever needs to be.

That heat and cold water quench is how you drive the hardening impurities out. Usually just from exposure to Oxygen which is trying to turn it into a sort of bronze.

Get an old style brake washer from any hydraulics on almost any bike and do it.

Cooker, Cherry red colour and throw into cold water. like a shot glass or something.

You will see all the scale come off, it's called annealing. Run the thing through a couple of heat cycles in air, what we breathe and it will be hard again.

Aluminium sort of does this.....Weld it and give it a few days to chill out and it starts being as tough as it was....

 

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18 hours ago, Mark/Foggy said:

Why would you try to use a sealant on a copper gasket?

It's whole porpoise is that you stick it in fire and get it cherry hot and when you quench it in cold water it's the ultimate bodge material. So soft that it will form to any machining irregularities and when it has waited a couple of days it's as strong as it ever needs to be.

That heat and cold water quench is how you drive the hardening impurities out. Usually just from exposure to Oxygen which is trying to turn it into a sort of bronze.

Get an old style brake washer from any hydraulics on almost any bike and do it.

Cooker, Cherry red colour and throw into cold water. like a shot glass or something.

You will see all the scale come off, it's called annealing. Run the thing through a couple of heat cycles in air, what we breathe and it will be hard again.

Aluminium sort of does this.....Weld it and give it a few days to chill out and it starts being as tough as it was....

 

This is what I bin doin for years, never had any problems, I always thought when you had a copper head gasket, you didn't need sealant, perhaps Mark and I are livin in the past.

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OK, so it looks like the " something else " is nothing.

Typical. 

Just wasted £18 on copper spray.

Anyway, in other news, gasket nearly finished, just the bore holes to cut to finish it.

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The thing is when you search around its hard to ignore people who have had issues and the amount of talk about about what sealer to use from old leaky Nortons to high BHP drag car engines. I think it can be a good solution* if you have no choice but may need some help to fully seal sometimes!

*Personally I would run the larger squish with the decent proper metal standard gasket and not worry myself with it!

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1 hour ago, dannn said:

The thing is when you search around its hard to ignore people who have had issues and the amount of talk about about what sealer to use from old leaky Nortons to high BHP drag car engines. I think it can be a good solution* if you have no choice but may need some help to fully seal sometimes!

*Personally I would run the larger squish with the decent proper metal standard gasket and not worry myself with it!

I'd love to , if I had standard barrels.

Just had the barrels re linered and they came back with the liners matched to the previous bad "porting" . It ran like a tuned 125.

Actually what I would have expected with raised exhaust ports and transfers all over the place, and liner blocking enlarged transfers.

Big midrange flat spot.

( two sets of meticulously cleaned carbs, all new jets and needles , ignition timing spot on, leakdown test fine)

Mismatched transfers sorted now, but still got the raised exhausts,  want some midrange back like my previous properly tuned LCs had, and they all had tightened up squish bands.

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On 5/12/2021 at 10:03 PM, Mark/Foggy said:

Why would you try to use a sealant on a copper gasket?

It's whole porpoise is that you stick it in fire and get it cherry hot and when you quench it in cold water it's the ultimate bodge material. So soft that it will form to any machining irregularities and when it has waited a couple of days it's as strong as it ever needs to be.

That heat and cold water quench is how you drive the hardening impurities out. Usually just from exposure to Oxygen which is trying to turn it into a sort of bronze.

Get an old style brake washer from any hydraulics on almost any bike and do it.

Cooker, Cherry red colour and throw into cold water. like a shot glass or something.

You will see all the scale come off, it's called annealing. Run the thing through a couple of heat cycles in air, what we breathe and it will be hard again.

Aluminium sort of does this.....Weld it and give it a few days to chill out and it starts being as tough as it was....

 

I'm not sure the clamping pressure on a head gasket from 8 bolts at 17lb/ft is anything like that of a copper washer.

Just thinking out loud here.

( well 20lb/ft, always torqued mine down a bit more, done loads if LCs that way with standard metal/fibre gasket with silicone sealant and never had one leak)

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This is an interesting thread about using copper gasket:

https://www.accessnorton.com/NortonCommando/sealer-for-copper-head-gaskets.22314/

https://jsmotorsport.com/technical-sealant-comparison/

Chap recommends using a glue called Pliobond 20 - looks like he has done plenty of testing as well!

I also quite like his use of the really thin copper wire around the oil passages.

Edited by dannn
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Following details on a copper cylinder head gasket manufacture used permatex copper gasket spray, left for 2 hours before assembly. 

Warmed it up, no leaks so far.

Sounds crisper and top end really quiet.

Test ride tomorrow evening if back from work at reasonable time and its not pissing down.

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12 miles, no leaks

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