Inlet rubber restorer?

[0l0dom0l0]

Having bought a new cylinder head for my bike, it has come with the inlet rubbers on . They are in a much better state than mine, and I was wondering if anyone knows anything I can put on them that will soften them up a bit? They are very brittle, and will probally split without much doing.

Whats safe to put on them? is WD40 a big NO-NO?

Thanks

[Phoenix]

WD40 is fine to lubricate them enough to slide the carbs in but it won't soften them up, gentle heat will soften them up temporarily and i've heard soaking them in oil works too. Personally if they are really hard I would buy some new ones, they're not terribly expensive and it saves hassle getting carbs on and off later plus minimises the chances of a split and/or an air leak. Recently bought new ones for my VFR because it's impossible to get the carbs on with rock hard rubbers.

[Nexus Icon]

A massive NO-NO, tbh. WD40 will make the rubber swell.

Silicon grease is safe on rubber but it's not always the easiest thing to find. I usually get it through work and I've no idea if Halfords and the like sell it.

[0l0dom0l0]

Well seeing as i have just forked out about £400 on stuff for my bike, i'm kinda skint now as you might imagine and new ones are £75

There is nothing wrong with them at all, I want to soak them in an oil to just protect them. What sort of oils would work? Are there any specific rubber oils?

[Livefast123]

Autoglym vinyl rubber care around £4.99 at most car shops
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Current ride - Yamaha MT-07

[0l0dom0l0]

That looks like the kinda stuff I am after. Thanks very much!

[Phoenix]

[Bezzer]

Silicone oil or grease is the best stuff and is readily available in DIY or plumbing places where it's sold to lubricate the rubber sealing collars on waste pipes, look in the plumbing section and you'll find it.
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I used to be indecisive but now I'm not quite so sure.

[Walloper]

WD40 has a lot of silicone in it. I use it to lube door seals on lifeboats. Just so we can get the fcukers open when abandoning ship.

There are silicon sprays available Halfrauds, for example, sell it in cans specifically for rubber lube.
I also use a little of it, sprayed onto a rag, to lube the seal around my helmet. (Crash Helmet )

As said it's a new head so the cost of a new rubber is not to be considered optional.
This is why reliability issues arise. Cutting corners can give you arse-ache later. And leaking inlet could be unwanted hassle when setting up after fitting the head.
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[DrDonnyBrago]

Walloper's points about replacing them seems like good advice.

However if you did decide to lube them up then plumbers silicone grease (cheap), or even red rubber grease would be my choice.

[Nexus Icon]

[0l0dom0l0]

Thanks for all the replies.

I will have a look for some silicone grease and such like

There is nothing wrong with them, that's why I'm not replacing them. I was after something that would just protect them, and replenish their natural oils, and soften them up to prevent them from cracking.

And yeah, if I had a spare £75 nocking around I would replace them. However I don't. I'm 17, and have already spend £1000 'doing up' aka fixing my bike. I'm broke.

[LongJohn22]

Search for "Silicone Grease" on flea-bay and you will be spoilt for choice. Very reasonably proced in most cases, too.

[Teflon-Mike]

Damn Dyslexia, I read the title as 'Indian Rubber Store'... not entirely sure what I expected it to be about, actually! ANYWAY.

Brake Fluid.

Bit of technical shit for you; rubber is a 'plasticised mixture', that is, its made from getting loads of different gunks and powders and cooking them up like a cake.

Polymer 'plastics' are homogeniouse materials having the same composition throughout curtecy of a chrystal lattice, and have inherent 'plastic', or soft maleable properties by virtue of technically being super-cooled fluids, rather than true solids.... all to do with the latent heat associated with a 'change of state'...

When Ice melts, it does so at 0 degrees, and it stays at 0 degrees throughout the transition, despite heat having to be put in or taken out to get it to change from a fluid to a solid.

Supercooled fluids, like plastic or glass, dont have that change of state, cole them down and they simply get more and more viscouse until they become so viscouse they are in effect a solid, but without a constant temperature heat exchance creating the change of state, technically they haven't actually become solid.

Anyway, rubbers are compounded, and depending on how they are forumlated, tend to be a bit of a soup. Sort of rubber used in automotive aplications, like tyres and stuff, would probably be best described as a supercooled fluid suspension.... basically rubber tree sap is the supercooled fluid, but held in suspension are solid powders, most noteably innert graphite carbon, in the parlence known as 'tread stop'. More graphite in the mix, harder the rubber compound tends to be, but then its cured to 'semi-set' the rubber by causing polymer cross-linking in its chrystaline structure.... but to prevent it becoming too brittle, there's also generally a degree of 'plastisiser' in the mix as well, either synthetic rubber or low viscosity man-made polymers, and or actual solvents.

Too much blarb.. I know..... BUT point is, reason rubber goes hard and crazes is that the plastisisers in the mix, over time leech out. That causes the rubber to shrink and go hard.

Provided the rubber hasn't degraded too far though, you can soften it back up, and bring it back to size a bit, by using 'something' that will soak back into the the rubber and replace the plastisisers. Remember, rubber is an organic material, like leather, and its pretty much the same as using a leather oil to treat an old hardened jacket.

WD40 or high silicone trim preparations can work, but the formula is basically a silicone suspension, and applying it to the rubber, the solvent soaks into the rubber dragging the silicone with it.

Trouble is, the light solvent that soaks in, just as readily leeches back out, leaving the silicone as the plastisiser, and on a thicker rubber part like a carb-rubber, often only in the outer surface layer, as it wont penetrate that far into the material, due to chromatography effect of the way it soaks in.

Brake fluid, is designed with plastisising solvents in its formulation to soak into and swell critical seals in the brake system AND keep them supple. Its design and forumulation is much more closely matched to doing what you want to do here, and it will penetrate the rubber better, and stay in the rubber longer.

I've done it a few times when impoverished, and its worked pretty well. But the trick is to give the rubbers a coating of brake fluid, wiped or brushed on, rather than soak them, and to do a number of repeat applications if necessary to get them fully suppled up. Remember to apply inside and out, as well.

If you soak them, then they can suck up an awful lot of fluid, and swell considerably! I had a 32mm diameter rubber swell to about 36mm when I left it over night in a saucer of brake fluid! Didn't seal to well when I tried putting the carburettor back in! so much over size it actually 'pleated' itself inside the jubilee clip! Also the more cracked & 'crazed' ends of the rubber soaked up more fluid from thier greater surface area, so it sort of went all bell-shaped as well!

But, if applied sparingly and in repeated applications, with a little care, they should soften up nicely, making them that bit more supple and less likely to tear when you re-fit them, and hopefully you'll get a bit more life out of them.
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[0l0dom0l0]

I have some old brake fluid knocking around so I will brush that on as you say. I can see your logic too. I though brake fluid was corrosive as f*ck though?

[james1988]

[Teflon-Mike]

[Walloper]

[Walloper]