Fin repair

modelman · Post by **modelman** » Thu Nov 09, 2017 10:34 am

Has anyone know if the fins on the 305 head can be repaired/re welded?
Just noticed that the two front fins under the right side valve-caps are bent down & cracked, obviously from a tool being over-used during cap removal, just touching them with a screwdriver shows them to be loose & broken all the way through, I'm sure I can pull them off.
They will DEFINITELY come away during aqua-blasting.
Any of you guys done this??

G-Man · Post by **G-Man** » Thu Nov 09, 2017 11:38 am

Modelman

I use Lumiweld / technoweld to put fins back on for the last 20 years or so. I also have heads that have been repaired with TiG or Oxyacetylene.

Technoweld is good for repairing 'middle' fins as it melts at a lower temperature than the aluminium. With genuine aluminium welding you sometimes have to cut a whole group of fins away and weld them back in a sequence as it is difficult to get the torch in without melting surrounding fins.

http://www.techno-weld.co.uk/home.html

It is a good idea to make up a hearth and use an insulating blanket to keep the heat in, allowing you to use a smaller torch. You can get materials like that here:

http://www.cupalloys.co.uk/home/

Here is a small repair I did to a tacho drive.

http://www.honda305.com/forums/post74867.html

G

modelman · Post by **modelman** » Thu Nov 09, 2017 1:06 pm

Do you know, that reminds me, I've had one of those kits kicking around somewhere in the workshop for many years & I totally forgot about it, never used it, & used the stainless brush for something else!!
I'll nip out & get a new brush & when the engine has been stripped, I'll give it a try, you never know, I might even manage to do it!!

Thanks for the info & write-up.

G-Man · Post by **G-Man** » Sat Nov 11, 2017 10:48 am

Here is a better example of what you can do with this stuff....

http://www.honda305.com/forums/1961-cb7 ... 1-693.html

G

modelman wrote:Do you know, that reminds me, I've had one of those kits kicking around somewhere in the workshop for many years & I totally forgot about it, never used it, & used the stainless brush for something else!!
I'll nip out & get a new brush & when the engine has been stripped, I'll give it a try, you never know, I might even manage to do it!!

Thanks for the info & write-up.

modelman · Post by **modelman** » Sat Nov 11, 2017 11:09 am

Managed to find the kit I have, its 'Durafix' & I realize i've had it about 20 years, but its still as new in its sealed tube!!
It seems to be just about identical to Lumiweld & the destructions are exactly the same!
I have an assortment of blowlamps & torches etc. as well as some refractories to cobble up a little hearth when brazing & silver-soldering, so when the time comes I'll give it a go.
Many thanks for your help & info.