Alloy Cylinder Head Fins need reattaching.

[Mr shiney]

I have a bike cylinder head that a couple of fins have snapped off. What's the best way to stick em back on? What's the best rod to use?

 

[mike os]

Durafix type stuff

 

[roofman]

Lumiweld

 

[Mr shiney]

Have a TIG and will stick it back on with that.

I have used the durafix before with limited success on cylinder heads. You just can't get enough heat into the job to get them to stick and then it just slumps without warning.

I would prefer to TIG it on. It's 5mm thick aluminium so should weld fine.

 

[Piero]

I tried this on a lambretta C head,

my brother had snapped off two fins,

he insisted I weld them back on,

I tried it on the first one, it went ok,

But I talked him into letting me build up a new one using filler rod.

This turned out to be a much better opption

 

[Mr shiney]

I tried this on a lambretta C head,

my brother had snapped off two fins,

he insisted I weld them back on,

I tried it on the first one, it went ok,

But I talked him into letting me build up a new one using filler rod.

This turned out to be a much better opption

I thought about it but it's a couple of big bits that have been snapped off. To much to build back up really.

 

[Shox Dr]

I'd build it up as well. doesn't take long

 

[backpurge]

Done the same with plenty of Lambretta heads, you will be surprised how quickly you can build them back up

 

[Mr shiney]

What's the best way to build them?

What rods should I use, 4043?

 

[hotrodder]

Yep, 4043. 4047 is the other choice. If you don't want to build a new fin out of weld and find what's left of the origionals welds like crap then cut them back a little and 'butter' each side of the joint with a pass or two of weld first... it's easier to get any crud out with a carbide burr this way and will give you two clean surfaces for the joint proper

 

[Mr shiney]

Yep, 4043. 4047 is the other choice. If you don't want to build a new fin out of weld and find what's left of the origionals welds like crap then cut them back a little and 'butter' each side of the joint with a pass or two of weld first... it's easier to get any crud out with a carbide burr this way and will give you two clean surfaces for the joint proper

Thanks. I will give that ago.

If I was going to build with weld, what's the best way to do it? Stick a Copper plate as a flat base and build the weld out on top of it or lay beads on top of each other?

 

[backpurge]

Lay beads on top of each other, watch the heat build up, it really is a lot easier than you might think

 

[Mr shiney]

Lay beads on top of each other, watch the heat build up, it really is a lot easier than you might think

Thanks! I will give it a try.

 

[doubleboost]

Thanks! I will give it a try.

You can build up damaged out board props the same way