Frame welding question

Ive had at least 3 different welders have a go at different bits on my frame. (1981CSR1000) Theyve all had the same problems. (very thin steel).
I did a welding course this weekend and brought the frame along. The instructor also had the same difficulties.
Is this an inherent problem with old kawasaki/japanese bikes or is it just my frame?
What is the best method for welding these frames? Mig,Mag,Tig,Tinkywinky,Dipsy,Lala,Po ???
Are other people struggling when welding their frames or is it Just me?
Any help/advise appreciated.

Hello buddy, not too sure about your frame specifically, I think you have seen mine in the photos, I found with my frame that on some of the welds there were signs of porosity but when dressed away there were also signs of penetration. I have done some good bits of welding on my frame and had my plant up quite high and never had an issue. I'm a welder by trade but in no way and expert in metal - but for what it's worth when I cut up my frame rails and removed brackets etc the wall thickness was absolutely fine and as previously stated apart from some very ugly welds done at source ( penetration being more important than aesthetics) the frame was fine to work with.

Tig will be your best choice. J models have thinner wall tubing than earlier KZs.
Surface preparation and low heat are needed. To much heat will draw out any contamination
on the inside wall of the tube. Also, most of the tubing will be sealed up. When
heated up by welding the pressure will rise inside increasing the chance of blowing a hole.


.

Ive stick welded plenty of z1/kz frames without a problem,never welded on a j frame that I can remember.

Plus 1 on TIG
More control over the welding process .
Just my 2cts
Dave

Some advice given to me when I was working on my frame... Take some extra (similar) tubing and slit it up one side. You want to slide it inside your frame so it straddles across the weld joint. The slit allows the tubing to expand so it tightly fills the area inside the frame, and the extra material gives you a lot more meat to weld, plus it holds your frame pieces aligned while welding.

Good idea for joining tubing,shdwdrgn,but my problems are just from welding up holes and putting on mounting brackets and such.Its nothing traumatic.I think the pressure building up inside makes sense and the fact that j models use thinner steel than earlier versions makes me feel a bit better. I was worrying that I could have a frame thats rotten inside and all the work/money/time etc Im putting into this build could go down the toilet (or across the tarmac!).
Ive got 2 more tabs to weld on and thats it. Ill have another go with the tig.
Cant wait for it to be done so I can start on the paint.
Thanks for the input