metal dust caps stuck

sithmaster

hi all, I have metal dust caps on my motorbike but they are stuck on I need to put air into the back tyre about half inflated


how can I get them off?


I have tried wd40 left overnight
boiling water


anything else I can try without ripping the valves out


thanks

Rolandtheroadie

Sorry for telling you how to suck eggs, but I assume you've tried mole grips and plyers and theres no flats on the dust covers that you could get a spanner onto? (access etc allowing).

sithmaster

scotsman4th wrote: »

Sorry for telling you how to suck eggs, but I assume you've tried mole grips and plyers and theres no flats on the dust covers that you could get a spanner onto? (access etc allowing).

tried pliers but the valve twists with it even with me holding the valve to stop it, sadly they are round

neilmcl

Get some direct heat on them, possibly try very carefully with a lighter.

flashg67

I've seen this a lot in my tyre-fitting days - the alloy/steel of the cap reacts with the brass valve stem - unless they're used with a bit of copper grease etc when first applied, they're best avoided imho. You're probably looking at changing the valves and having boring black caps fitted.....

snowcat75

neilmcl wrote: »

Get some direct heat on them, possibly try very carefully with a lighter.

Heat and tyres no, I used to always reach for the O/A torch to free stuck nuts on super singles, someone pointed me in the direction of this.

marlot

If you cut across the top (very carefully) with a a junior hacksaw, you may be able to peel the cap away, tearing the sides of the cap.

Strider590

Metal as in alloy?

VERY common problem, if you carefully grind away one side until you see the valve thread, they shouild come off easily.

Plastic caps might not look so great, but I'd never use anything else.

facade

snowcat75 wrote: »

Heat and tyres no, I used to always reach for the O/A torch to free stuck nuts on super singles, someone pointed me in the direction of this.

They set fire to the tyre on the inside. Probably had filled it with oxygen rather than plain air to make sure it went up.

If you are welding a rim, take the tyre off first

You will never do that just warming the valve cap with a cooks blowlamp or a lighter.

Anyway, just cut the side of the cap away, it doesn't matter if you damage the threads on the outside slightly.

snowcat75

facade wrote: »

They set fire to the tyre on the inside. Probably had filled it with oxygen rather than plain air to make sure it went up.

If you are welding a rim, take the tyre off first

You will never do that just warming the valve cap with a cooks blowlamp or a lighter.

Anyway, just cut the side of the cap away, it doesn't matter if you damage the threads on the outside slightly.

Really???

That reaction is caused by exothermic, the initial heat is the cataylist, there was no fire, the heat rise is caused by a reaction.

The video was a demo Rig, demonstrating the potentials of what Can truly happen, It will not happen with every tyre and possible 99% of the time the sulphr/ carbon and the initial heat inputs are incorrect to get such a reaction. but the 1% when your wrong they will bite.

This sort of reaction is so tremendous that tires that have been slipped from the bead prior to heating can be forced back on and still explode.

Iv witnessed first hand tires exploding with no warning, the forces are tremendous, as the compressed gas volumes at something like 30% as it hits atmosphere.

Still as you clearly know far more than I am, Im off to kick a bottle of acetylene across the yard, weld a petrol tank, stand over a split rim super single whilst seating it then after lunch Il think il do a shonkey repair to a pressure vessel.

Those lads who advice against those sort of things must know less than someone on an internet forum.

sithmaster

thanks for the reply's will try the suggestions