Welding Frames

[utsman]

I need to weld a crack in my CR500 frame . It is right at the bottom and easy to access. What do i need to be carefull of ie, can I damage the ignition etc, splatter on the cases. Any thoughts appreciated.

STU

[vandy010]

pull the motor out stu and do it properly. use either Mig or Tig

[oldyzman]

Hey UTSMAN, I agree to a large extent about removing the motor, The point i would like to highlight is the frame material. Many of the old Mxers are made of cromoly (yz125e, cr250m, etc) if you use mig with a steel wire then you may not get a strong weld. Ask around to find out what material your frame is. If it is cromo then you should use tig with the correct filler rod. If you have little welding experience then dont put it to chance... OLDYZMAN

[Brett]

I reckon its best to remove all electrical components completely from the bike when welding. Better to be safe than sorry.

[utsman]

Oh NO - I certainly won't be doing the welding. Motor out eh. What a mission but still, must treat the old girl right'

[oldyzman]

hey utsman, if you r sydney based maybe i can give you a doods number to weld it...
OLDYZMAN

[Marc.com]

disconnect the electrics, if you want to do it motor in the frame make sure the earth is on the frame next to where you are welding so you don't arc through the bearings. TIG is the only kind of welding that counts, MIG will crack about the edges usually if the parent metals and wire are not the same. I use stainless TIG rods, never had problem.

[GMC]

if you want to do it motor in the frame make sure the earth is on the frame next to where you are welding so you don't arc through the bearings.

Yes, very important.

I have welded cases while the motor was still in the frame at times, very awkward.
but the worst thing is the customers complain about having to remove the oil as its fresh

TIG is the best option for welding, normal TIG wire will interchange with cro-mo allright but obviously the cro-mo wire will be the stronger weld.

MIG will do the job also but you will need some experiance to tackle it properly, its too easy to lay down a big bead of weld with MIG thats not burnt in, these would be the welds that crack at the edges.

[PEZBerq]

GMC, iIf you weld with CrMo do you need to stress relieve by heat treating?  I asked John LeFevre of Vintage Husky about welding CrMo Husky frames once and he said he used mild steel filler wire.  Its not the weld thats the weak point in these frames...or is it My 2 cents...

[Lozza]

 As Geoff said welds crack in the Heat Affected Zone(HAZ) that is the bit in between the filler and the parent material. Weld ductility is greatly enhanced by stress relief after welding but not essential for just 1 weld, maybe for a frame welded on a production line in quick time . For this you just have to gradualy heat the area, weld, then slowly cool it makes a ductile weld. The only time I would say you have a frame problem if a frame is welded and it cracks again in the same spot.

[firko]

When tig welding chromo I always used 346 stainless steel wire and never had any problems.

[oldyzman]

Hey firko is that 316 or 346 s/s filler rod, genuine question?

[firko]

Oops...I meant 316. My old brain must be fading fast. Sorry to anybody who'd gone looking for 346 rods as they may just have had a bit of a tough time finding 'em.

[oldyzman]

Thats interesting to know firko, I guess chromolly has a certain amount of chromium and so does 316 s/s
Never really thought of it that way

[Lozza]

I had read on the subject and seems I was incorrect in my assumption that normal triple deoxidised filler wires are no good on CrMo/4130 tube. They are OK but not as good as CrMo filler, sorry to play bad cop agin on you firko but it took me a while to find it here is what John Bradley in the Racing Motorcycle Vol2(what I usualy refer to) has to say on the stainless filler on CrMo subject.