[marsheng]

I've done quite a bit of welding over my time but this one has got me. It is a Suzuki T250 cylinder head. I wanted to reshape the squish.

I welded up a the original squish band and machined it. Horrible full of holes. I then re-machined out a 2-3 mm recess around the squish, rewelded and I had a reasonable finish when I turned it. There were still a few holes, so I thought I could gently fill these in with a small amount of heat and 4047 rod. On re-machining ughh. More holes than before. You can see the ring (1) where the new wire fill meets the original casting. (2) is the machined weld, not too bad and (3) is the reweld trying to fill on the holes after machining.

Stuck on how to go forward.

[weldin mike 27]

Hey there,

The air pockets of which you speak are referred to as porosity. Aluminium is notorious for it. Everything you do needs to be super clean. (Unless you are a welding god) Clean all surfaces well with acetone and a stainless steel wire brush. The oil from machining and or in the casting from use will play curry with everything( this may need cleaning before acetone/wire brushing). You may need to machine out the added metal and start again. Clean the filler rod with scotchbrite as well. Someone here may be able to assist with AC balance settings to aid your situation, but I can not.

Regards, Mick

[cj737]

Also, these are old, cast aluminum parts. When you weld them, the heat creates expansion in the air pockets trapped within the original casting.

What has worked for me, is to use lower heat, a higher balance, and 50Hz (if your machine will adjust to that). I also use 5356 wire. I am not looking for heavy penetration, just fusion. I walk the torch around the entire area first to clean the oxide off, cook out some goop, then clean it with Acetone. Then put some wire to it on the second go-around.

Maybe that will help you-

[marsheng]

When I weld, I preheat the head and then carefully lay down a bead. If I get a pocket come up, then I heated it enough to bring it to the top. Did all that and thought I had a good surface, Once I machined it, the 100s of holes opened up. These were not there when I welded (although they must have been !!)

I used 4047 as it was the lowest melting rod.

[thespian]

When I did 2 strokes in the past, I soaked the head in Acetone for about 3 hours to get everything good, and clean, then if I had issues , I would heat it up a few times let it cool ,and re soak it. That seemed to work every time for me.

[marsheng]

Acetone sounds like an idea, however I have already welded it. Have I then not already turned the oil in the head into carbon which probably wont dissolve in the acetone ?

Thanks Wallace New Zealand.

[cj737]

Acetone sounds like an idea, however I have already welded it. Have I then not already turned the oil in the head into carbon which probably wont dissolve in the acetone ?

If you're done welding it, then an acetone wipe/bath is pointless. But preheat and acetone before welding are very beneficial.

[LtBadd]

Acetone sounds like an idea, however I have already welded it. Have I then not already turned the oil in the head into carbon which probably wont dissolve in the acetone ?

If you're done welding it, then an acetone wipe/bath is pointless. But preheat and acetone before welding are very beneficial.

Just don't apply the acetone while it's heated!!

[Poland308]

Once the holes become evident, sometimes all you can do is grind some out and keep rewelding. As you add new filler metal you might be able to get most of the trash to work to the surface. Where you can keep grinding it away.

[marsheng]

A bit more testing and even worse results. See attached. Even the fins have now got bubbles.




'
This one has got me.

[motox]

over the years i have welded a lot of various Japanese aluminum motorcycle parts like cylinders, case parts, swingers, clutch perches, sub frames etc. some brand years weld ok some look like your problem. if it doesn't weld ok, most times it
never will... just my experiences..
craig