Titanium

[Wriggler]

Anyone welded it?

Is it hard to do?

I've been asked to repair a power valve for a motorcross bike and looking on the net there seems to be quite a bit of conflicting advice mainly about gas shielding.

The two schools of thought seem to be
1 you need a piece of special equipment to get the gas right

2 you don't need this special equipment just turn the gas flow right up

Someone thought the valve was ali and has had a little go so there is a small piece melted.

Any advice or is it leave well alone.

 

[Drains]

Wriggler, I've not welded Titanium, but I can tell you the issue you have to deal with is that the weld needs to cool with a gas shield, hence the advice to use a trailing shoe (I assume that is the "special equipment" you mentioned).
It doesn't matter how you do it, so long as you protect the weld. A trailing shoe might not be appropriate for the job you have anyway. - How big a weld do you have to do?

Be careful about just turning up the gas though, as you may well draw in air to the weld. A gas lens will guarantee a better gas flow, and a big gas lens may allow you to turn it up enough to cover the weld area.

 

[Wriggler]

Cheers

Yes a trailing shoe was mentioned.

There are two welds that need to be done, about 20mm each.

 

[Rick]

Big gas lense and do 10mm at a time, alternatively use a trailing purge.

 

[TechnicAl]

Get it done by someone who has experience. Its very expensive stuff. You could spend a lot of money and end up with scrap.

 

[rodofgod]

Hi All!

Wriggler,I have welded quite a bit of Titanium, mainly for aerospace work and it is very easy to weld! However, it is very susceptible to atmospheric contamination when hot! Hence the use of trailing purges etc. to protect the metal whilst it is cooling down!
If you can come up with a way of preventing this atmospheric contamination then you should be ok with such small welds!
However, there are several types of alloys of Titanium and you should really match the filler wire! Also, if someone has had a go before you and contamination has already taken place, then the part is scrap!
The good thing is, it's quite easy to tell if it's been contaminated! If the metal is 'straw' coloured around the area welded, it should be ok, if it's blue or even white, it's scrap! The colour of the metal is a guide to the contamination that has occurred!

Regards

 

[mike os]

if its that small.... do it in a box?

 

[Paul G]

Hi,

You need argon on the underside of the joint too.

I have done joints that require 3 back purges, a follower and the torch.

Cheers
Paul G

 

[wyn]

What bike is it off ?

When i was racing motocross bikes i'm sure no two stroke power valves were made of titanium.

inlet and exhaust Valves in 4 strokes mx bikes are sometimes titanium.

It probably is aluminium but a grade that is not easily welded...a 2xxx series aluminium ? or more likely it is cast and has a fair bit of exaust carbon contaminating it.

 

[Wriggler]

It's off a 2004 Yamaha

It needs a good clean with acetone

 

[mr migwire]

2stroke power valve from a yz, bin it and get a new one.

the tollerances are way to tight to weld and dress it and hope it works.

if the guy races his bike tell him to invest in a new one, if it's just a field bike then give it a go.

 

[Wriggler]

I was wrong about the bike.

It's off a Suzuki 125.

His new one is a Yamaha.

 

[Wriggler]

2stroke power valve from a yz, bin it and get a new one.

the tollerances are way to tight to weld and dress it and hope it works.

if the guy races his bike tell him to invest in a new one, if it's just a field bike then give it a go.

He's been told £200 for a new one

 

[wyn]

This link (follow the links to the 2004 RM 125 exhaust valve) shows them for $37 in the US..if that is the right part.

 

[Wriggler]

This link (follow the links to the 2004 RM 125 exhaust valve) shows them for $37 in the US..if that is the right part.

Cheers.
I'll show him that.

 

[Autolupus]

That looks like ali not titanium.

 

[rodofgod]

Hi All!

Yeah! looks like ali too me as well!

Regards