Welding Tips and Tricks

Hello, i just purchased a go kart and the engine that came with it has two cracks on the coolant passage. I was curious if i would need to take something and grove out the cracks before i try to tig weld the cracks? Any help or opinions would be greatly appreciated!

It's always a good idea to grind out the bad and fill in with new good. Could be grime, more cracking thats not visible, or other bad stuff in there.

If you can, remove that part and clean it inside and out. Even if it’s liquid cooled, there’s still contamination absorbed in the casting. Cast ally is a bear to weld to not get porosity. I use 50Hz, 65 Balance, and low heat. Grind it out, heat with propane, clean it really well, and go easy on the amps to soften the edges. Just enough heat to wet the filler without seeking “penetration”. Use a long postflow to help cool the weld slowly to avoid cracking.

Good luck-

Thank you very much for the tips! I just got in my filler metal and Will shoot to do the repair tomorrow or later today and I will take pictures of the results!

All seems fine , but it will be a major problem with distortion so first tacks and most of the welding will be with the
head assembled without gasket well torqued or you will have a bad surprise ...4047 tig rod .

probably already warped....

From the pictures it looks like a Rotax Max FR125. In that case it's not worth welding the barrel, the distortion will almost certainly affect the bore. They have a nikasil coated bore so cannot be rebored or honed.

You should be able to pick up a replacement barrel cheaply enough, in Australia they are plentiful. If you are running under any sanctioned body a welded barrel would most likely be illegal anyway.